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Mahasarakham International Journal of Engineering Technology

MIJET

Volume 1, Number 2, July – December 2015

http://mijet.engineer.msu.ac.th

ISSN 2408-1957

A peer-reviewed publication by Faculty of Engineering, Mahasarakham University, Thailand

MIJET

ISSN 2408-1957


Owner Faculty of Engineering, Mahasarakham University, Thailand

Editor-in-Chief Professor Sampan Rittidech, Ph.D., Thailand

Editorial Board Professor Apirat Siritaratiwat, Ph.D., Thailand Professor Yulong Ding, Ph.D., UK Professor Prinya Chindaprasirt, Ph.D., Thailand Professor Vichate Ungvichian, Ph.D., USA Professor Patrick Wheeler, Ph.D., UK Professor John Black, Ph.D., Australia Professor Stanislav Makhanov, Ph.D., Thailand Professor Guenter Schroeder, Ph.D., Germany Professor Masahiro Otaki, Ph.D., Japan Professor Kosin Chamnongthai, D.EE., Thailand Professor Osamu Watanabe, D.Eng, Japan Professor Chai Jaturapitakkul, Ph.D., Thailand Professor Supachai Patomnakul, Ph.D., Thailand Professor Lih-sheng Turng, Ph.D., USA Professor George Srzenicki, Ph.D., Australia Professor Parames Chutima, Ph.D., Thailand Professor Jan Pieters, Ph.D., Belgium Associate Professor Seni Karnchanawong, Ph.D., Thailand Associate Professor Patcharee Hovichitr, Ph.D., Thailand Associate Professor Ampawan Tansakul, Ph.D., Thailand Associate Professor Somchai Chuan-udom, Ph.D., Thailand Associate Professor Mario Attard, Ph.D., Australia Associate Professor Manukid Parnichkun, Ph.D., Thailand

Associate Editor Assistant Professor Chonlatee Photong, Ph.D. Associate Professor John Morris, Ph.D. Associate Professor Sudsakorn Inthidech, Ph.D. Assistant Professor Juckamass Laohavanich, Ph.D. Assistant Professor Niwat Angkawisittpan, Ph.D. Assistant Professor Petch Pengchai, Ph.D. Assistant Professor Nida Chaimoon, Ph.D. Assistant Professor Teerapat Chompookham, Ph.D. Assistant Professor Lamul Wiset, Ph.D. Assistant Professor Kiattisin Kanjanawanishkul, Ph.D. Assistant Professor Yottha Srithep, Ph.D. Dr. Noppadol Sangiamsak, Ph.D.

Assistant Editor Kessarin Phuphanee

Contact Office

2 issues/year: (January-June) and (July-December) ISSN 2408-1957 (print) ISSN 2408-1566 (online)

Issue/Periodicity

MIJET Editorial Office, Faculty of Engineering, Mahasarakham University, Kham Riang, Kantarawichai, Maha Sarakham, 44150, Thailand Tel.: +66 (0) 437-54316 Fax: +66(0) 437-54316 E-mail: [email protected] Website: http://mijet.engineer.msu.ac.th

Editor-in-Chief’s Note Dear Readers, After our hard working, the Mahasarakham International Journal of Engineering Technology (MIJET), volume 1, number 2 (July-December 2015) is now ready to show off. There are five distinguished research papers published in this volume; four research papers and one review paper. In the first part of the journal, the abrasive wear resistance of hypoeutectic 16 wt% and 26 wt% Cr cast irons with molybdenum has been examined and analyzed; following by an application of microcontroller for controlling the hydroxy gas (HHO) dry cell in small trucks. In the second part, effects of extraction factors on total phenolic compounds and antioxidant activity in mulberry leaves, and the analysis and characterization of the nutrient concentration of That Luang Marsh attributed to wastewater discharges from Vientiane city, Lao PDR, have been proposed. In the last part, the topic of sustainable polymers: from recycling of non-biodegradable to renewable resources composites and foams has been reviewed. I am sure that these research works will bring you some useful information, as well as, some new ideas for your further research and development. I would like to take this opportunity to sincerely thank to all the authors for their contributions of research findings, as well as, to all the honorary reviewers for their comments and advice on the submitted manuscripts that could enhance the published work in MIJET to have even higher quality. I hope that the MIJET could promote the further development and advance in engineering technologies, which would eventually drive and sustain human well-being.

Signature Professor Sampan Rittidech, Ph.D. Editor-in-Chief of MIJET

About MIJET The Mahasarakham International Journal of Engineering Technology (MIJET) was launched in 2015 by the Faculty of Engineering, Mahasarakham University, Thailand. MIJET is a peer reviewed, open-access, international journal for the publication of the research in the fields of engineering technology including, but not limited to, the following topics: Energy engineering Civil and water resource engineering Mechanical engineering Mechatronic engineering Agricultural, biological and food engineering Biological engineering Chemical and petroleum engineering Material engineering Industrial and manufacturing engineering Automotive engineering Computer and software engineering Electrical engineering Electronic and telecommunication engineering Transport and logistics engineering Environmental engineering Business management engineering Renewable science technology engineering Engineering education MIJET is published online twice a year. The aim of MIJET is to provide communication platform for researchers in engineering fields from all over the world. MIJET is devoted to the publication of original research papers and reviews in various fields of engineering. Authors are required to confirm that their paper has not been submitted to any other journal and no part of the manuscript has been plagiarized. The authors who intend to submit the manuscript to the MIJET journal has to follow the following processes:

- Go to MIJET webpage: http://mijet.engineer.msu.ac.th - Find “My account” to create your account via the login form and then complete the submission form. - The manuscript must be prepared in English and passed the journal template. - Once the author completes the submission, author may receive a confirmation email for confirming the

submission. - The author can follow the progress via the on-line system by using login and password (notification of

acceptance would normally provide by an email no longer than 6 months since the date of submission). For any other enquiries or questions, please contact: [email protected] or post to: MIJET Editorial Office Faculty of Engineering, Mahasarakham University, Kham Riang, Kantarawichai, Maha Sarakham 44150, Thailand Tel.: +66-43-75-4316; Fax: +66-43-75-4316

Contents

Research Papers Abrasive Wear Resistance of Hypoeutectic 16 wt% and 26 wt% Cr Cast Irons with Molybdenum S. Inthidech, Y. Matsubara …………………………..……………………………………………………………. 1 Application of Microcontroller for Controlling HHO Dry Cell in Small Trucks W. Sa-ngiamvibool, A. Aurasopon …………………….……………………………….…………………………. 10 Effects of Extraction Factors on Total Phenolic Compounds and Antioxidant Activity in Mulberry Leaves P. Supakot, J. Kubola, C. Bungthong …………………………….…………………………………………….... 14 Analysis and Characterization of the Nutrient Concentration of That Luang Marsh Attributed to Wastewater Discharges from Vientiane City, Lao PDR S. Inkhamseng, V. Vilaysane …………………………………..……………………………………..…………… 20

Review Paper Sustainable Polymers: From Recycling of Non-Biodegradable to Renewable Resources Composites and Foams Y. Srithep, L. Turng, J. Morris, D. Pholharn, O. Veangin ……...………………………………………………… 24

MAHASARAKHAM INTERNATIONAL JOURNAL OF ENGINEERING TECHNOLOGY, VOL. 1, NO. 2, JULY-DECEMBER 2015 1

Abrasive Wear Resistance of Hypoeutectic 16 wt% and

26 wt% Cr Cast Irons with Molybdenum

Sudsakorn INTHIDECH1,*

and Yasuhiro MATSUBARA2

1,* Faculty of Engineering, Mahasarakham University, Kham Riang, Kantarawichai, Maha Sarakham 44150, Thailand

2 National Institutes of Technology- Kurume College, Fukuoka, Japan, 811-1313

[email protected]

Abstract. Hypoeutectic 16 wt% and 26 wt% Cr cast

irons with nil, 1 and 3 wt% Mo were prepared in order to

investigate their abrasion wear resistance. The annealed

test pieces were hardened from 1,323 K and then tempered

at three levels of temperatures between 673 and 823 K for

7.2ks, the temperature giving the maximum hardness

(HTmax), lower temperature than that at HTmax (L-HTmax) and

higher temperature than that at HTmax (H-HTmax). The

abrasive wear behavior was evaluated using the two-body

type abrasion wear test or Suga abrasion wear test. It was

found that hardness and Vγ in the heat-treated specimens

varied depending on the Cr and Mo contents. A linear

relation was obtained between wear loss and wear

distance. The lowest wear rate (RW) was obtained in the

HTmax specimen. The highest RW was obtained in the H-

HTmax specimen. Under the same heat treatment condition,

the RW in 16% Cr cast iron was much larger than that in

26% Cr cast iron. The RW decreased with increasing the

hardness in the both series of the cast irons. The lowest RW

obtained in the specimen with a certain amount of retained

austenite, 25%Vγ in 16% Cr cast iron and 15%Vγ in 26%

Cr cast iron, respectively.

Keywords:

High chromium cast irons, abrasive wear resistance, heat

treatment, hardness, volume fraction of retained austenite

1. Introduction

Alloyed white cast irons containing 15-30 wt% Cr

(hereafter shown by %) have been employed as abrasion

wear resistant materials for more than 50 years. The

microstructure of these alloys consists of hard eutectic

carbides and strong matrix providing the excellent wear

resistance and suitable toughness. It is well known that 15%

to 20% Cr cast irons have been commonly used for rolling

mill rolls in the steel plants, while cast irons with 25% to

28% Cr have been applied to rollers and tables of

pulverizing mills in the mining and cement industries. High

Cr cast irons with hypoeutectic composition are preferable

because they are free from precipitation of primary carbides

that reduce the toughness [1]-[3]. As-cast microstructure of

hypoeutectic composition consists of austenite dendrite and

eutectic M7C3 carbides. The austenite is stable at high

temperature and in an equilibrium state, it transforms to

ferrite and carbides on the way of cooling. However, under

non equilibrium state, the austenite may remain stable or

partially transform to pearlite or martensite depending on

the chemical composition and the cooling rate [1],[2].

Austenite is favored by high cooling rate, high Cr/C ratio

and addition of Ni, Cu and Mo [1]-[3]. The supersaturation

of Cr and C in the austenite depresses the martensite start

temperature (Ms). Resultantly, the austenite exists even at

the room temperature.

Austenite has low hardness and so toughness is high

but it can be work-hardened during service to increase the

surface hardness. However, it should be limited for the

spalling problem. Improvement of performance for wear

resistance and mechanical properties can be obtained by

heat treatment and addition of alloying elements which give

the martensitic matrix with higher wear resistance. In the

most cases, a suitable martensitic matrix is preferred to

increase the abrasion wear resistance. To obtain the

martensitic matrix, the cast iron is held in austenite region

at 900-1,100 oC to enable secondary carbide precipitation

that is called as destabilization of austenite, and followed

by fan air cooling to room temperature. The precipitation of

secondary carbides in the matrix during heat treatment must

be also related to the wear resistance and somewhat to the

mechanical properties [4],[5]. The retained austenite should

be normally less than 10% by single or multiple tempering

to avoid the spalling during service [3]. In practical,

applications of high chromium cast iron, adequate heat

treatment should be given to the cast iron to get an optimal

combination of the hardness and the toughness which is

mainly controlled by quantity of retained austenite. Since

quantitative measurement of retained austenite for the high

chromium cast iron has been performed successfully by X-

ray diffraction method [6]-[14]. It is possible to clarify the

relationship between properties such as wear resistance,

hardness and the amount of retained austenite.

The purpose of alloy addition is to avoid the

formation of pearlite in the as-cast condition and to

improve the hardenability during heat treatment. Since Cr is

present in both the eutectic and secondary carbides, the rest

of Cr retains in the matrix and increase the hardenability, by

suppressing the pearlite transformation. Therefore, the

addition of the third alloying elements such as Mo, Ni, Cu

2 MAHASARAKHAM INTERNATIONAL JOURNAL OF ENGINEERING TECHNOLOGY, VOL. 1, NO. 2, JULY-DECEMBER 2015

are needed to harden the matrix fully [1]. The researches of

alloying elements to high chromium cast iron have been

extensively carried out [5]-[16]. It was reported that the

highest hardness after heat treatment of 16% and 26% Cr

cast iron was obtained by Mo addition [8]. This is because

of the fact that Mo can form its special carbide of Mo2C or

M2C with extremely high hardness as eutectic and

secondary precipitates [4]. These carbides result in an

increase of abrasion wear resistance.

The commercial high chromium cast irons used for

wear parts in many kinds of industries, have been usually

heat-treated. Hence, the wear resistance should be

evaluated relating to heat treatment conditions. Many

laboratory tests have been carried out to evaluate the

abrasion wear resistance. However, the test data was not

often valid to simulate correctly the wear behavior occurred

in the industrial applications. Therefore, it is considered

that the systematic and detailed studies on the abrasive wear

behavior must be requested. Particularly, the systematic

investigation of Mo addition on the abrasion wear and heat

treatment behavior is much more important. There are

many researches on the wear resistance of high Cr cast

irons [3],[5],[13]-[16], and recently authors reported the

effect of Mo content on the heat treatment behavior of

hypoeutectic high Cr cast irons [8]. However, the

systematic researches on the effect of Mo content on

abrasion wear behavior of heat-treated high chromium cast

irons have not been carried out.

In this study, hypoeutectic 16% Cr and 26% Cr cast

irons with 0 to 3 % Mo were prepared in the heat-treated

state, and the abrasion wear resistance was evaluated using

a two-body-type abrasion wear tester or Suga type wear

tester. The relationships between abrasion wear resistance

and hardness, volume fraction of retained austenite (Vγ) and

Mo content were clarified. In addition, the wear behaviors

were discussed in connection with the microstructure in the

cast irons.

2. Experimental Procedures

2.1 Preparation of Test Specimens

Individual charge calculations were performed in

order to obtain the target chemical compositions in the test

specimens. Total heat of 30 kg was melted in a high

frequency induction furnace with an alumina (Al2O3) lining

and superheated at 1,853 K. After holding for 600 s, the

melt was poured at 1,773-1,793 K into a preheated CO2

bonded sand mold in Y-block shape which consists of a

cavity for the specimen with 50x50x200 mm and sufficient

volume of the riser. After pouring, the melt was

immediately covered with dry exothermic powder to hold

the temperature of riser. The chemical compositions of the

test specimens are shown in Table 1. The schematic

drawings of Y-block casting and the process to make the

test pieces is shown in Fig. 1.

Table 1 Chemical composition of test specimens

Fig. 1 Schematic drawings of processes to make test pieces:

(a) shape of casting, (b) substantial part and (c) test

pieces

2.2 Heat treatment procedures

The riser was cut off from the Y-block ingot. The

remaining substantial block was annealed at 1,173 K for 18

ks and sliced into test pieces with 7 mm in thickness using a

wire-cutting machine. The sliced test pieces were

austenitized at 1,323 K for 5.4 ks and air cooled by a fan.

The as-hardened (As-H) test piece was tempered at three

temperatures from 673 to 873 K for 7.2 ks, the temperature

giving the maximum hardness (HTmax) and the lower and

higher temperatures than that at HTmax (L-HTmax, H-HTmax).

These three temperatures were determined referring to the

tempered hardness curves shown in the previous work [8].

Specimen Element (wt%)

C Cr Si Mn Mo

No.1 2.96 15.93 0.51 0.55 0.22

No.2 2.95 16.00 0.50 0.55 1.06

No.3 2.91 15.91 0.47 0.55 2.98

No.4 2.66 26.08 0.47 0.55 0.18

No.5 2.64 26.12 0.50 0.56 1.02

No.6 2.71 25.98 0.47 0.53 2.96


2.3 Measurement of Hardness and Retained

Austenite

The macro-hardness of test specimens were measured

with a Vickers hardness tester employing a load of 294 N

(30 kgf). More than five indents were taken on each

specimen and the measured values were averaged. The

volume fraction of retained austenite (Vγ) was obtained by

X-ray diffraction method using a simultaneously rotating

and swinging sample stage. The diffraction peaks adopted

for calculation are α200, α220 for ferrite or martensite and

α220, α311 for austenite [6],[8]-[13].

2.4 Observation of Microstructure

To observe the microstructures, specimens were

polished using emery papers in the order of No.180, 320,

400, 600 and then finished by a buff cloth with extremely

fine alumina powder of 0.3 μm in diameter. The

microstructures were revealed using Vilella’s reagent. The

microstructure observation was performed by an optical

microscope (OM) and a scanning electron microscope

(SEM). As for the SEM investigation, the secondary

electron image was taken using an accelerating voltage of

20 kV and a working distance of 15 mm.

2.5 Abrasion Wear Tests

Surface roughness of test piece was kept less than

3µm Ra-max using a grinding machine. A schematic

drawing of Suga type abrasion wear tester is illustrated in

Fig. 2. The force of 9.8 N (1 kgf) is applied from the

abrading wheel contacted to the test piece. A 180 mesh SiC

abrasive paper is fixed on the circumference of an abrading

wheel. The wheel moves forth and back for 30 mm stoke on

the same area of the test piece. Simultaneously, the wheel is

rotated intermittently 0.9 degree per stroke, that is, the

speed of rotation of the wheel was 0.345 mm/s. Since the

worn area is 12x30 mm2 (360 mm

2), the total of distance of

Fig. 2 Schematic drawing of Suga abrasion wear tester

one revolution or 360 degrees is 2,400 mm and the total

area is 12x32x400 mm2 (9,600 mm

2). After each test,

the specimen was cleaned with acetone in an ultrasonic

bath and then dried. The weight loss of the test piece

was measured using a high precision digital balance with

0.1 mg accuracy. The test was repeated for eight times

on one test piece.

3. Experimental Results and Discussions

3.1 Characterization of As-Hardened Test

Specimens

The SEM photomicrographs of as-hardened 16% and

26% Cr cast irons with and without Mo are displayed in

Fig. 3. The matrix structure consists of a large number of

fine precipitated carbides, martensite and retained austenite.

It was reported that the secondary carbides which

precipitated in the as-hardened state of high chromium cast

irons are mostly M7C3 carbides co-existing with M23C6

carbides [1],[3]. The retained austenite, which existed more

in the as-cast state, is destabilized to precipitate fine

secondary carbides during holding and transforms into

martensite during cooling. In the specimen of 16 % Cr with

3% Mo, it is clear that the M2C eutectic carbides

crystallized in the residual liquid after precipitation of

primary austenite are observed.

Hardness and Vγ of test specimens are summarized in

Table 2. These test pieces with different hardness and Vγ

were supplied to the abrasion wear test. It is found that

hardness and the Vγ change significantly depending on the

heat treatment condition and Mo content. The Vγ in the as-

hardened state is higher than that the tempered state. It is

clear that the Vγ value of L-HTmax specimen is greater than

those of HTmax and H-HTmax specimens.

Specimen

Heat treatment

condition

Hardness

(HV30) V, %

16% Cr

No.1 (Mo-free)

As-H (1323 K)

L-HTmax (673 K)

HTmax (748 K)

H- HTmax (773 K)

822

755

786

748

25

21

6

2

No.2 (1%Mo)

As-H (1323 K)

L-HTmax (673 K)

HTmax (798 K)

H- HTmax (823 K)

811

744

831

718

38

32

12

2

No.3 (3%Mo)

As-H (1323 K)

L-HTmax (673 K)

HTmax (823 K)

H- HTmax (873 K)

824

762

816

654

40

33

18

2

26% Cr

No. 4 (Mo-free)

As-H (1323 K)

L-HTmax (673 K)

HTmax (723 K)

H-HTmax (773 K)

810

743

769

751

7

6

4

1

No. 5 (1% Mo)

As-H (1323 K)

L-HTmax (673 K)

HTmax (748 K)

H-HTmax (800 K)

865

782

818

714

13

9

5

2

No. 6 (3% Mo)

As-H (1323 K)

L-HTmax (673 K)

HTmax (748 K)

H-HTmax (823 K)

873

831

849

710

15

12

10

6

Table 2 Hardness and volume fraction of retained austenite

(Vγ) of specimens with different heat treatment


16% Cr cast iron 26% Cr cast iron

(a) Mo-free

(b) 1% Mo

(c) 3% Mo

Fig. 3 As-hardened microstructures of hypoeutectic 16% and 26% Cr cast irons without and with Mo

Martensite


3.2 Abrasion Wear Behaviour

In order to prepare the specimens with matrix

structure consisting of various phases or constituents, the

three different temperatures which give the different

amount of hardness and Vγ as well as microstructure, were

employed for tempering. It is normally known that the wear

resistance is also influenced by Mo content which affects

the matrix transformation and which in turn influenced the

type, morphology and amount of carbide, the amount of

austenite and martensite. Here, the effects of heat treatment

condition and Mo content on the wear resistance are

described.

The relationships between wear loss and wear distance

are shown in Fig. 4. The figure shows the results of the test

specimens under different heat treatment conditions of As-

H, L-HTmax, HTmax and H-HTmax, and for the cases of 16%

and 26% Cr cast irons. In all diagrams, the wear loss

increases in proportion to the wear distance regardless of

the kind of specimen and heat treatment condition. In each

diagram, the slope of the straight line which means the wear

rate (Rw) of the specimen, varies according to the

difference of heat treatment conditions.

In the 16% Cr cast iron, the difference in wear loss of

the Mo-free specimen is influenced a little by the difference

of heat treatment. In the Mo-bearing specimens, the

difference in wear losses according to the condition of heat

treatment are revealed clearly compared with that in Mo-

free specimen, and it can be seen that the wear losses are

smallest in the specimen with 3% Mo. The similar relations

are obtained in the 26% Cr cast irons. At the same Mo

content, however, the total wear losses of 26% Cr cast iron

are smaller than those in the 16% Cr cast iron.

Since the linear relationships were obtained between

wear loss and wear distance for all the test specimens, it is

suitable to adopt an index of wear rate (Rw: mg/m) as a

description of the wear resistance, which is expressed by

the slope of each straight line. The RW values of all the

specimens are summarized in Table 3.

It is found that the smallest RW or the largest wear

resistance is obtained in the specimens with HTmax in which

matrix contains large portion of tempered martensite and

some retained austenite except for the Mo-free specimen

which shows the smallest RW in the As-H specimen. The

largest RW or the smallest wear resistance is obtained in all

the specimens with H-HTmax where a large portion of

martensite is tempered to ferrite and carbides and the

retained austenite is mostly decomposed. It is clear that the

smallest RW or the largest wear resistance is obtained in the

specimen with 3% Mo in the 16% Cr and 26% Cr cast

irons.

Specimen Heat treatment condition Wear rate (Rw), mg/m

16% Cr 26%Cr

Mo-free

As-H 0.45 0.39

L-HTmax 0.47 0.42

HTmax 0.46 0.40

H-HTmax 0.48 0.43

1% Mo

As-H 0.47 0.38

L-HTmax 0.48 0.41

HTmax 0.44 0.37

H-HTmax 0.51 0.43

3% Mo

As-H 0.45 0.37

L-HTmax 0.44 0.38

HTmax 0.42 0.35

H-HTmax 0.56 0.41

Table 3 Wear rate of test specimens with different heat treatment

conditions

Since, it can be considered that both of hardness and

Vγ influence on the Rw. The relationship between RW and

hardness is obtained for all specimens in Fig. 5. Though the

RW values are a little scattered, they decrease in proportion

to the hardness regardless of heat treatment condition and

Mo content. The relations are expressed as follows:

16% Cr cast iron: Rw (mg/m) = (-5.3x10-4

) x (HV30)

+0.884 (R = 0.85)

26% Cr cast iron: Rw (mg/m) = (-3.8x10-4

) x (HV30)

+0.694 (R = 0.86)

It is clear that the higher the hardness, the smaller the

RW or the larger the wear resistance. In the tempered state,

therefore, the specimen with HTmax has the largest wear

resistance in both the 16% and 26% Cr cast irons. To

clarify the sensitivity of the RW effect to an increase in

hardness between 16% and 26% Cr cast irons, the slopes of

the lines, α1 for Fig.5 (a) and α2 for (b), respectively, are

calculated. The ratio of α1 to α2 (α1/α2) is 1.39 and this

means that the hardness effected the RW of 16% Cr cast

iron around 40% more than that of 26% Cr cast iron.

The relationships between RW and Vγ are shown in

Fig. 6 (a) for 16% Cr and (b) for 26% Cr cast irons. The

relationship between these two parameters can be expressed

by the following equations,

16% Cr cast iron: Rw = (1.2x10-4

)x(Vγ)2

- (6.3x10-3

)x(Vγ) + 0.520 (R = 0.67)

26% Cr cast iron: Rw = (2.6x10-4

)x(Vγ)2

- (6.8x10-3

)x(Vγ) + 0.432 (R = 0.58)


16% Cr cast iron 26% Cr cast iron

(a) Mo-free

(b) 1% Mo

(c) 3% Mo

Fig. 4 Relationship between wear loss and wear distance of heat-treated 16% and 26% Cr cast irons with and without Mo


(a) 16% Cr cast iron (b) 26% Cr cast iron

Fig. 5 Relationship between wear rate (Rw) and hardness of the specimens

(a) 16% Cr cast iron (b) 26% Cr cast iron

Fig. 6 Relationship between wear rate (Rw) and volume fraction of retained austenite (Vγ) of the specimens

It seems that the minimum value of RW is obtained at

about 20% Vγ in the 16% Cr cast iron and 10% Vγ in the

26% Cr cast iron. This suggests that a certain amount of the

retained austenite could be available to improve the

abrasion wear resistance. The decrease in the RW to a

lowest Rw value is due to an increase in the hard martensite

and the precipitation of secondary carbides in the matrix

and that in the strength of matrix. At very low Vγ value, the

RW is relatively high in both the 16% and 26%Cr cast irons

because the matrix is contained of pearlite and coarse

secondary carbides.

The effect of the Mo content of the cast iron on the

RW is shown in Fig. 7. The RW decreases totally a little as

the Mo content increases and the decreasing rate is similar

between 16% and 26% Cr cast irons. From the results, it

can be concluded that an increase in Mo content to 3%

improves the wear resistance of hypoeutectic 16% and 26%

Cr cast irons. At the same Mo content, the Rw value of

16% Cr cast iron is larger than that of 26% Cr cast iron.

From Fig. 7, the 26% Cr cast iron shows the better

wear resistance than the 16% Cr cast iron. The reason can

be explained as follows:

In the specimens, the volume fractions of eutectic

carbides are almost same, 36.2% in 16% Cr and 36.4% in

26% Cr specimens, respectively. Resultantly, it is

considered that the effect of the amount of eutectic carbide

on the Rw is less between the 16% and 26% Cr specimens.

When the hardness of HTmax are compared between the

specimens with 1% Mo, they are almost the same, 831

HV30 and 818 HV30 for 16% Cr and 26% Cr, respectively.

It can be considered from these results that the difference in

the wear resistance between 16% and 26% Cr specimens


Fig. 7 Effect of Mo content on wear rate (Rw) of 16% and

26% Cr cast irons

arises from the difference in the morphology and the

hardness of eutectic carbides. That is, the morphology of

eutectic carbide in 16% Cr cast iron is thicker and more

interconnected in comparison with that of 26% Cr cast iron

which is fine and less interconnected. It is well known that

the hardness of eutectic carbides in the 26% Cr cast iron is

higher than that in the 16% Cr cast iron due to more

dissolution of Cr [1]-[3]. Under a high stress abrasion

occurred by the abrasives with very high hardness, the

harder and tougher carbides provide the better resistance.

As mentioned before, Mo distributed in the austenite during

solidification influences the transformation of matrix. The

partition coefficient of Mo to the austenite is given as the

ratio of Mo content in austenite to that in the quenched

liquid, 0.36 for 15 % Cr and 0.45 for 30 % Cr cast irons,

respectively [17]. More Mo concentration in the matrix of

26 % Cr cast iron promotes more precipitation of hard

secondary carbides with Mo. It is possible by tempering

that some special molybdenum carbides could precipitate as

a result of carbide reaction in the martensite.

Here, it can be said that the Mo gives a positive effect

on the wear resistance of 16% and 26% Cr cast irons. This

is because the Mo represses the formation of pearlite in the

as-cast condition and improves the hardenability. From

wear test results of heat-treated specimens, the wear

resistance increases with an increase in the hardness as well

as that in the Mo content. As the Mo contents increase, the

Mo distributed to the austenite promotes not only to

precipitate the molybdenum carbides with extremely high

hardness but also the Mo in M7C3 eutectic carbide increases

the hardness of the carbide. The presence of a certain

amount of M2C carbides is beneficial for the wear

resistance because it could prevent the propagation of

cracking in the matrix [4].

3.3 Mechanism of Abrasion Wear

In order to comprehend the abrasion wear behavior,

the SEM microphotographs of 1% Mo specimen with HTmax

are taken and representative examples of worn surface are

shown in Fig. 8 (a) for 16% Cr and (b) for 26% Cr cast

irons, respectively. In the both specimens, the abraded

regions showing fine lines caused by scratching correspond

to the matrix areas. On the microphotographs, it is found

that the eutectic carbides are worn a little by scratching and

more by spalling or pitting, and much rougher worn

surfaces are formed by grooving and tearing. The matrix is

preferably cut off or worn and removed more than the

eutectic carbides. The cracks occur probably in the eutectic

carbides because the load concentrates on the carbides. As

a result, spalling of carbides could take place. The tearing

and grooving are observed because the austenitic matrix

with more ductility can be deformed easily without

cracking by the stress of abrasive particles [3]. The tearing

could form in the matrix area of the grooving. In addition,

this plastic deformation could absorb the mechanical

energy applied by the abrasive particle [3]. As a result, the

grooving is narrow in the austenitic region. It is clear from

the photographs in Fig. 8 that the worn surface of 16% Cr

cast iron is heavily deformed more than that of 26% Cr cast

iron. These results agree well with the data of abrasion

wear test.

(a) 16% Cr cast iron

(b) 26% Cr cast iron

Fig. 8 SEM microphotographs of worn surfaces of 1%Mo

specimens with HTmax


4. Conclusion

The abrasive wear behavior of heat-treated

hypoeutectic 16% and 26% Cr cast irons without and with

Mo was investigated. After annealing, the specimens were

hardened from 1,323 K (As-H) and tempered at three levels

of temperatures, the temperature giving the maximum

hardness (HTmax), and the lower and higher temperature

than the HTmax temperature, (L-HTmax, H-HTmax). The effects

of hardness, volume fraction of retained austenite (Vγ) and

the heat treatment conditions on the abrasion wear behavior

were clarified. The following conclusions have been drawn

from the experimental results and discussions.

1) The linear relationship was obtained between

wear loss and wear distance. The largest wear resistance or

the smallest RW value was obtained in the specimen with

HTmax except for the Mo-free specimen. The smallest wear

resistance or the greatest RW value was obtained in the H-

HTmax specimen. The RW value in the 16% Cr cat iron was

much larger than that in the 26% Cr cast iron.

2) The RW decreased with an increase in the

hardness. The hardness had more effect on 16% Cr cast

iron than 26% Cr cast iron.

3) The smallest RW appeared in the specimen with a

certain amount of retained austenite, 20%Vγ for 16% Cr

cast iron and 10%Vγ for 26% Cr cast iron, respectively.

4) The RW was decreased with increasing the Mo

content of the specimen. At the same Mo content, the Rw in

the 16% Cr cast iron is higher than that in the 26% Cr cast

iron. The smallest Rw was obtained in the specimens with

3% Mo in both the 16% and 26% Cr cast irons.

5) The matrix was preferably cut off or worn and

removed faster and much more than the eutectic area. When

this process continued, the cracks were caused in the

eutectic carbides, and resultantly, the spalling could take

place and the eutectic carbides are removed. The coarser

worn surface was formed by such grooving and tearing.

Acknowledgements

The authors gratefully acknowledge to the Thailand

Research Fund, the Commission on Higher Education and

Mahasarakham University for the research funding.

References

[1] G.L.F Powell, Metals Forum, Vol. 3 (1980), p. 37-46.

[2] Y. Matsubara, K. Ogi and K Matsuda, AFS Trans. Vol. 89 (1981),

p.183-196.

[3] G. Laird, R. Gungdlach and K. Rohring, Abrasion-Resistance Cast

Iron Handbook (American Foundry Society, USA, 2000)

[4] M. Ikeda, ISIJ International. Vol. 32 (1992), p.1157-1162.

[5] S.K. Yu, N. Sasaguri and Y. Matsubara, Int. J. Cast Metals Res.,

Vol. 11 (1999), p. 561-566.

[6] C. Kim. J. Heat treating ASM. Vol. 1 (1979) p. 43-51.

[7] I.R. Sare and B.K. Arnold , Metal Trans A. Vol. 26A (1995), p.

359-370.

[8] S. Inthidech, P. Sricharoenchai and Y. Matsubara: Mat. Trans.

Vol. 47 (2006), p. 72-81.

[9] S. Inthidech, P. Sricharoenchai, N. Sasaguri, Y. Matsubara: AFS

Trans. Vol. 112 (2004), p. 899-910.

[10] P. Sricharoenchai, S. Inthidech, N. Sasaguri, Y. Matsubara: AFS

Trans. Vol. 112 (2004), p. 911-923.

[11] S. Inthidech, P. Sricharoenchai and Y. Matsubara: Mat. Trans.,

Vol. 49 (2008), p. 2322-2330.

[12] S. Inthidech, K. Boonmak, P. Sricharoenchai, N. Sasakuri and Y.

Matsubara, Mat. Trans., Vol. 51 No. 7 (2010), p. 1264-1271.

[13] S. Inthidech, P. Aungsupaitoon, P. Sricharoenchai and Y.

Matsubara, Int. J. Cast Metals Res. Vol. 23 No.3 (2010), p. 164-

172.

[14] G. Laird II, AFS Transactions. Vol. 99 (1991), p. 339-357.

[15] C.P. Tabrett, I.R. Sare and M.R. Ghomashchi, Int. Mater. Rev.,

Vol. 41 (1996) p. 59-82.

[16] G. laird and G.L.F. Powell, Mat. Trans., Vol. 24A (1993), p. 981-

988.

[17] Y. Ono, N. Murai and K. Ogi: ISIJ., Vol 32 (1992), p. 1150-1156.


Application of Microcontroller for Controlling

HHO Dry Cell in Small Trucks

Worawat SA-NGIAMVIBOOL* and Apinan AURASOPON

Faculty of Engineering, Mahasarakham University, Maha Sarakham, 44150, Thailand

[email protected]*

Abstract. This paper proposes an application of

microcontroller for controlling the HHO dry cell regarding

to separate hydrogen gas from water. The proposed control

system consists of a display control microcontroller, a

PWM signal generation microcontroller, key switches,

buck converter, a separator and sensors. The experimental

results show that the proposed control system can regulate

the output current of the HHO dry cell constantly; even

under the significant variations of battery voltage or the

change in dry cell internal resistance. Furthermore, the

proposed system could also protect the system operation by

limiting the minimum voltage for the battery and maximum

output current and temperature of the HHO dry cell. The

test of the prototype truck by running for 15,000 kilometers

was found that the truck could save the fuel approximately

by 10 % when applied the proposed control system as the

co-fuel source. In addition, one liter of pure water could be

used for the operating engine and could operate

continuously up to 800 kilometers.

Keywords:

Microcontroller, hydrogen, HHO dry cell

1. Introduction

The depletion of conventional fossil fuels (i.e. natural

gas, coal and oil) and the increase of energy demands for

supporting the higher number of world population and the

growth of industries worldwide lead to the need of more

energy to be shared from renewable resources. Extracting

energy from the chemical reaction would be one of the most

interesting renewable energy production techniques [1].

In fact, producing energy from the chemical reaction

with hydrogen gas is currently the most focused technique

due to the simple possible methods to generate the gas;

where the gas can be easily produced in terms of hydrogen

gas and oxygen gas (or hydroxy gas or HHO) from small

electrolytic plates of stainless steel that dipping in the

potassium hydroxide solvent [2]. Alternatively, the gas can

be produced from the decomposition of water, which will

give the hydrogen and oxygen from a molecule of water

using electrolysis effect with a productive ratio of 2:1.

However, producing energy from hydrogen gas with

the electrolysis effect would encounter some problems

related to the risks of fire explosion due to

overcurrent/voltage or temperature, as the hydrogen gas is a

flammable material. In addition, the process of generating

hydrogen gas can be very slow and thus would spend much

time for giving significant amount of hydrogen and energy

[1],[3].

To eliminate the aforementioned problems, this paper

proposes the implementation of the control system using

microcontrollers in order to increase the production rate of

hydroxy gas from the HHO dry cell. The proposed control

system also consists of the feedback control and safe

operation monitoring unit. The simple PIC microcontroller

was used for the experimental prototype.

The experimental results show that the proposed

control system could regulate the generated electric current

of the HHO dry cell even the resistance of the cell is varied

due to the inhomogeneous of the salt-water mixing solvent;

including also the case of variation of battery voltage. The

additional monitoring system was also implemented in

order to ensure safe operation of the system; where the

system will cut off the HHO dry cell from the electric

charger when battery voltage becomes lower or the

temperature presents on the HHO dry cell becomes higher

than the limiting values.

2. Hydrogen Electrolysis Process

Fig. 1 shows the block diagram of the hydrogen

electrolysis system under this study. The system consists of

a HHO dry cell, a separator, a filter and a dc power supply

(or an electric charger system) [3]-[5]. From Fig. 1, when

the dc power supply powers an electric current through the

HHO dry cell, the electrolysis reaction will begin to

operate. The process produces the gas bubbles containing

some water, oxygen and hydrogen. These three products

then will be separated by the separator using weight

classification technique. After that, the pure oxygen (O2)

and hydrogen (H2) are cleaned by the special filter. These

gases are then injected into the ID pipe mixing with oil as

the fuel energy for the further using; such as for electric

cars or trucks.


Fig. 1 Block diagram of hydrogen electrolysis

3. The Proposed Control System

Fig. 2 shows the block diagram of the proposed control

system used to control the output current of the HHO dry

cell. The proposed control system has two microcontrollers,

key switches, a power inverter and sensors. The first

microcontroller is used for controlling and processing the

control parameters of the system, which can be switched for

displaying by key switches. The key switches are used for

selecting one of two operating Modes: Mode 1 and Mode 2.

The Mode 1 is used for displaying the measured parameters

of the system: the temperature, output current and battery

voltage. The Mode 2 is used to control the parameters

related to safe operation of the system: minimum battery

voltage level, maximum output current and maximum

allowable temperature. The second microcontroller is used

as the PID controller for generating proper control signal in

terms of pulse width modulation (PWM) signals. The

control signals are used to control the operation of the

switches and thus generate desired output current from the

HHO dry cell.

In order to achieve the designed control targets, the

output current from the HHO dry cell is measured on-line

and is fed back to the PID microcontroller. The PID

microcontroller then compares the measured value of

current with the desired reference value. The current error

then is used as an input signal for the PID controller that

therefore gives the control signal for controlling the switch

with proper gains of proportional, integral and derivative

controller. The control signal used is in the form of PWM

signal, which is a series of pulses with variable pulse width

depending on the level of output HHO dry cell current. In

this research, the PIC microcontrollers with build-in feature

and with the Mikro C Pro programming base are used. This

type of microcontroller is used for this research due to its

simple programming functions, as well as, having low

price. The generated PWM signal is then amplified in order

to have sufficient voltage levels for driving the power

MOS-FET as shown in Fig. 2.

The display microcontroller is also able to communicate

and synthesize to the PID microcontroller via the RS-232

series port. The dc buck converter is used for the power

conversion part of the control system; where its average

output voltage can be determined by integrating the square

wave pulse across the HHO dry cell. The average output

voltage of the HHO dry cell must be varied in order to

regulate the equivalent resistance seen across the HHO dry

cell’s terminals. This will give then the constant output

current from the cell. Fig. 3 shows the prototype of the

proposed control system, while Fig. 4 shows diagram and

photograph of the test control system prototype.

Fig. 2 Block diagram of the proposed control system


Fig. 3 Implemented circuit for the proposed HHO dry cell control system

HHO Dry

Cells

Controller

System

Hydroxy gas

Diesel

Engine

AAmp

Meter

Fuse

Relay on when

engine run

Switch + -

Battery

Bubbler

(a) (b)

Fig. 4 (a) diagram and (b) photograph of the test rig of the proposed HHO dry cell control system


4. Experimental Results

From Fig. 4, the system prototype was implemented

with a 2500 cc, turbo-intercooler, small-truck vehicle. The

battery used for the small-truck vehicle was used as a power

supply for the HHO dry cell generator as well as for all the

control system equipment. The hydrogen gas was applied to

a conventional diesel engine through the bubbler.

The experiment test-rig was able to produce the

hydrogen gas and generated amount of electric current of

12-14 A, voltage of 12-13.5 V, surrounding temperature

levels near a series of HHO dry cells in the range of 35-45 oC under the test of water circulating rate of 500 to 800

ml/min. continuously. The HHO dry cell limit control

parameters were set by having the maximum output current

of 10 A, minimum battery voltage of 10 V and maximum

temperature of 40 oC.

As it is difficult to find the transfer function or the

HHO dry cell, the optimal PID parameters of the control

system can be found using Ziegler - Nichols tuning method.

The method provides the control values for the PID

controller of KP= 96, KI=48 and KD=8; where the scaling

factor is 8 and switching frequency 2 kHz. The measured

parameters of the HHO dry cell and battery voltage in

comparison to the control signal for the buck inverter are

shown in Fig. 5 and Fig. 6, respectively.

Fig. 5 LED display screen for (a) output current, (b) temperature

and (c) battery voltage

Fig. 6 Measured waveforms of (a) Battery voltage and (b) control

signal

In addition, when the 2500 cc, turbo-intercooler,

small-truck had installed with the HHO dry cell gas

generator as with fully control by the microcontrollers. The

test of running the vehicle by 15,000 kilometers test has

proven that the proposed controller can save the fuel by

approximately 10 % when applied the HHO dry cell in

small trucks with the proposed control system as a co-fuel.

One liter of pure water could be used for the operating

engine and operate continuously with the test distance up to

800 kilometers for a trial operating truck.

5. Conclusions

This paper proposed the control system for hydrogen

electrolysis. The proposed control system was implemented

by the PIC microcontrollers. The experimental results show

that the control system can maintain the HHO dry cell

current constantly even under the significant variation of

battery voltage and cell resistance. In addition, for safety

issues, the proposed control system can limit the maximum

reactor current and cut off the power circuit from the

battery voltage when the battery voltage is lower than the

set point value efficiently.

References

[1] Ando Yuji., Tadayoshi Tanaka. Proposal for a new system for

simultaneous production of hydrogen and.hydrogen peroxide by

water electrolysis. International Journal of Hydrogen Energy,

29(2004), 1349-1354.

[2] Grigoriev S.A., V.N. Fatrrv. Pure hydrogen Production by PEM

electrolysis for hydrogen energy. International Journal of

Hydrogen Energy 31(2006), 171-175.

[3] R. McConnell and J. Thompson. Generating hydrogen through

water electrolysis using concentrator photo voltaic. NREL/CP,

(2005).

[4] Sa-ngiamvibool. W., The H2O-Dry-Cell Control System for Car.

Journal of Practical Electrical Engineering, 3(2011), 62-69.

[5] Pattanachak, E., Pattanasethanon, S., and Sa-ngiamvibool, W.,

Application Technique of Hydrogen and Oxygen for Co-Fuel

Small Trucks. Journal of Practical Electrical Engineering. 3(2011),

22-30.


Effects of Extraction Factors on Total Phenolic

Compounds and Antioxidant Activity in Mulberry

Leaves

Pianpan SUPAKOT1, *

Jittawan KUBOLA2 and Chuleeporn BUNGTHONG

3

1 Postharvest Technology and Agriculture Machanery Research Unit, Faculty of Engineering, Maharakham University

Kham Riang sub-district, Kantarawichai District, Maha Sarakham 44150 Thailand 2,3

Department of Science, Burirum Rajabhat University

439 Jira Road, Naimuang sub-district, Muang District, Buriram Province 31000 Thailand

[email protected]*, [email protected] and [email protected]

Abstract The objective of this study is to examine

effects of ultrasonic-assisted extraction on bioactive

compounds of mulberry leaves in compared with the

conventional extraction method. The mulberry leaves used

for this research were cleaned and dried by hot air drying

technique at 60°C for 5 hours. The ethanol concentration

of 50% and 80% with ethanol soaking time of 60 minutes

and extraction time of ultrasonic treatments at 20, 30 and

40 minutes were used. The experimental results showed

that the ultrasonic-assisted extraction provided highest

total amout of phenolic content and DPPH scavenging

activity compared with the controlled samples (p≤0.05). In

addition, increasing extraction time could further increase

total phenolic content and DPPH scavenging activity; with

50% ethanol and extraction time of 40 minutes provided

the highest total phenolic content and DPPH scavenging

activity under the tests.

Keywords:

ultrasonic-assist extraction, mulberry leaves, bioactive

compounds

1. Introduction Mulberry is one of the traditional Thai herbs that is

usually used to as a part of drinking releases or as herbal

medicines. In most Asian countries, mulberry leaves are

also used to feed silkworms (Bombyx mori L.) [1]. This is

because the mulberry leaves have enrich with proteins and

important bioactive compounds such as flavonoids and

phenolic compounds; where these compounds help to

reduce oxidative stress and provide low blood sugar [2]. It

has been reported that mulberry leaves, also the extracts of

mulberry leaves, exhibit multiple therapeutic effects such as

anti-diabetic, anti-inflammation and anti-cancer effects [3].

Phytochemical investigation has indicated that there are

many active constituents, such as flavonoids, alkaloids,

polysaccharides, phenolic compounds and steroids in the

mulberry leaves [4]. However, these compounds require

proper methods to extract them from the leaves for further

uses. In fact, the extraction method is the most important

factor that affects both quantity and quality of extracted

compounds.

There are several extraction methods proposed in the

literatures [5]-[7]. However, among those methods few

most traditional extraction methods have usually used,

which are Soxhlet extraction [8], heating reflux extraction

[9], maceration and shaker extraction [10]. The Soxhelt

extraction utilizes a laboratory equipment called Soxhlet

extractor which is designed to extract a lipid from a solid

material. The Soxhlet extraction is typically used when the

desired compound has a limited solubility in a solvent

whereas the impurity is insoluble in that solvent. However,

this method is suitable only for unmonitored and

unmanaged operation with less efficient recycling a small

amount of solvent to dissolve a larger amount of material

[11]. The heating reflux extraction, these procedures have

distinct drawbacks, such as the consumption of large

volumes of solvent and amounts of energy, low yields and

lengthy extraction procedures that can result in the loss or

degradation of target compounds [9]. Although, the

maceration and shaker extraction methods is the most

commonly used method to extract. The shaker extraction is

simple and safe, high temperature and long time of

maceration and shaker extraction lead to the degradation of

bioactive compounds [12]. Unfortunately, it seems that all

the aforementioned methods would have some

disadvantages about their long extracting time and/or high

amount of consuming energy. These lead the traditional

extraction methods an inefficient method as well as effects


on deformation of bioactive compounds [13]. Alternatively,

the ultrasonic- assisted extraction proposed in [14] that was

originally used for the applications of bioactive compound

extraction from many kinds of herbs and plants. The

acoustic cavitation in ultrasonic assisted extraction can

destroy cell walls, then reduce particle sizes and finally

decomposition the contacts between solvents and bioactive

compounds [15]. Moreover, the ultrasonic-assisted

extraction method has also some advantages regarding low

energy consumption, low solvent comsumption, high

extraction efficiency and high level of automationity [16].

However, the study of effects of extracting bioactive

compounds from the mulberry leaves using the ultrasonic-

assisted method has not been proposed, which is the

objective of this research.

Therefore, this paper presents the experimental results

on effects of ultrasonic-assisted extraction on bioactive

compounds of mulberry leaves by focusing on the phenolic

compounds and antioxidant activity of mulberry leaves.

2. Materials and Extraction Methods This section describes the processes to prepare the

mulberry leaves, explanation of principle and set-up of the

ultrasonic-assisted extraction method, the parameters and

techniques used to investigate and analyze effects of the

ultrasonic-assisted extraction method on bioactive

compounds of prepared mulberry leaves.

2.1 Preparation of Mulberry Leaves

Mulberry leaves type CV. Burirum no. 60, the

most common type of mulberry leaves in Thailand, were

used in this experimental study. The leaves as shown in Fig.

1(a) were harvested during their full growing stages from

the Sericulture Research Unit, Mahasarakham University,

Thailand. The prepared mulberry leaves were immediately

washed and dried at 60 °C for 5 hours, regarding standard

proposed in [17]. Then, the sample leaves were ground and

sieved with 80 meshes. Finally, they were kept away from

light in a disscicator at the controlled room temperature of

25 oC until they were analytical bioactive compounds,

having physical photographs as shown in Fig. 1(b).

(a) harvested full stage leaves (b) final dried-sieved leaves

Fig. 1 physical photographs of the mulberry leaves type CV. Burirum

no.60 under study during (a) harvested full stage leaves and

(b) final dried-sieved leaves.

2.2 Ultrasonic-Assisted Extraction

The ultrasonic-assisted extraction equipment used for

the experimental tests was a rectangular bath model Kj-300

Wuxi Kejie Ultrasonic Electronic Equipment Co., Ltd. The

equipment has an inner dimention of 300x240x150 mm

with an ultrasonic power and frequency source of 150 W

and 60 kHz [18]. The extraction temperature was controled

at 30 °C. The sample beakers were immersed into the

ultrasonic bath for ultrasonic waves under extraction

conditions of 50% and 80% ethanol and solvent to solid

ratio of 250 ml per 30 g. The test samples were sonicated at

a constant temperature of 30 °C with frequency of 60 kHz

for 10, 20 and 40 minutes. In order to validate the

experimental results, the conventional solvent extraction

was carried out with the same ethanol concentration of 50%

and 80%, but with the extraction time of ultrasonic

treatment at 20, 30 and 40 minutes, while applying ethanol

soaking time of 60 minutes and 50 g of the ground powder

was mixed with ethanol for smooth the tests.

After the ultrasonic treatment, the samples were

centrifuged with centrifugal speed of 6000 rpm for 20

minutes. The samples then were kept at 4 °C for better

separation of compounds. After that the samples were

filtered through a 0.45-µm membrane filter. Finally, the

filtrates were collected for HPLC analyses.

2.3 Determination of Total Phenolic

Compounds

The filtrates obtainded from the untrasonic-assisted

extraction then were sent to test quantitative of total

phenolic compounds. The total phenolic compounds were

analyzed by using a high performance liquid

chromatography in comparison to the standard liquid (gallic

acid) using LUNA Colum (size of 4.6x250 mm and

diameter of 5 mm). The mobile phase A was used with 3%

acetic acid while the mobile phase B with 25%

acetronotrile per 72% water; under test conditions of diode

array detection at 278 nm, velocity of a fluid at 1.2 ml/ minute. Finally, the peak areas were calculated that

eventually gave values of total phenolic compounds. The

unit of total phenolic compounds were expressed in mg

gallic acid equivalent per gram of sample weight (mg

GAE/100g) [19].

2.4 DPPH Radical Scavenging Activity

Antioxidant activity of the crude extract was

evaluated by DPPH radical scavenging assay [5]. Briefly,

50 µl of the 60% ethanol mulberry leaves extract prepared

as described before, 50 µl of 40% ethanol aqueous solution

(v/v), and 50 µl of 0.2 M of morpholinoethanesulfonic acid.

The mulberry leaves extract was diluted with 60% ethanol

aqueous solution. The reaction was intiated by adding 50 µl

of 0.1 M DPPH in ethanol. After left standing for 20

minutes at the room temperature of 25 oC, the reaction


mixture absorbance at 517 nm was measured by the

spectrophotometer. The results expressed as a percentage of

inhibition that can be calculated using equation (1).

% radical scavenging = 100xA

AA

control

samplecontrol (1)

; where Acontrol and Asample are the absorbance of control and

absorbance of mulberry leaves extract, respectively.

2.5 Statisticical Analysis

The triplications were performed for each treatment.

The significance of difference of total phenolic compounds

and antioxidant activity was calculated though a one-way

ANOVA procedure. The results obtained from the HPLC

analysis were expressed as the mean value ± standard

deviation. Duncant´s multiple range tests were used to

determine the significant difference among the treatments

with the p-values less than 0.05.

3. Results and Discussions

The moisture contents of the dried mulberry leaves

were between 12-14% (dry basis), which would not be

significantly different among diferent conditions (p>0.05).

As shown in Fig. 3, the total phenolic contents of mulberry

leaves were analyzed by using a high performance liquid

chromatography. The standard material used for the

experiment was the gallic acid. The concentration rates of

gallic standard were varies between 0, 20, 40, 60, 80 and

100 ppm. The retention time of the gallic standard was at

about 5 minutes (Fig.2).

Fig. 3 and Fig. 4 show experimental results obtained

from the chromatogrames of the gallic acid in mulberry

leaves with ethanol concentration of 50% and 80%,

respectively. The extracted mulberry leaves were analyzed

by a high performance liquid chromatography. The

retention time of the gallic standard at about 5 minutes was

used as a reference for comparing with the extracted

mulberry leaves. The peak areas were used to calculated the

total phenolic compounds for the mulberry leaves and had

results as shown in Table 1. The ultrasonic extraction by

using ethanol concentration at 50% was found that the total

phenolic content higher than the control variable (p≤0.05).

The total phenolic compounds increase with increasing of

ultrasonic extraction time (p>0.05). The use ultrasonic

extraction could induce the acoustic cavitation and rupture

of plant cell and this facilitates the flow of solvent in to

plant cell and enhances the desorption from the matrix of

solid sample, and thus would enhance the efficiency of

extraction based on cavitation phenomenon. The results

agreed with the expectations proposed in sugar beet

molasses[12]. However, the increase of extraction time may

not affect to the total phenolic contents of mulberry leaves

(p>0.05).

Fig. 2 Experimental result obtaind from chromatogram of gallic acid

(Standard) 100 ppm.

Fig. 3 Experimental result obtaind from chromatogram of gallic acid

(Standard) and Ethanol concentration of 50% by used ultrasonic

extraction time on total phenolic contents of mulberry leaves.

Control

Retention time5.12, Peak area 200852

50% ethanol, ultrasonic 20 minutes







Fig. 4 Experimental Result obtaind from chromatogram of gallic acid

(Standard) and Ethanol concentration of 80% by used ultrasonic

extraction time on total phenolic content of mulberry leaves

Fig. 3 and Fig. 4 show experimental results obtained

from the chromatogrames of the gallic acid in mulberry

leaves with ethanol concentration of 50% and 80%,

respectively. The extracted mulberry leaves were analyzed

by a high performance liquid chromatography. The

retention time of the gallic standard at about 5 minutes was

used as a reference for comparing with the extracted

mulberry leaves. The peak areas were used to calculated the

total phenolic compounds for the mulberry leaves and had

results as shown in Table 1. The ultrasonic extraction by

using ethanol concentration at 50% was found that the total

phenolic content higher than the control variable (p≤0.05).

The total phenolic compounds increase with increasing of

ultrasonic extraction time (p>0.05). The use ultrasonic

extraction could induce the acoustic cavitation and rupture

of plant cell and this facilitates the flow of solvent in to

plant cell and enhances the desorption from the matrix of

solid sample, and thus would enhance the efficiency of

extraction based on cavitation phenomenon. The results

agreed with the expectations proposed in sugar beet

molasses[12]. However, the increase of extraction time may

not affect to the total phenolic contents of mulberry leaves

(p>0.05).

Condition of extraction Total phenolic compounds

(mg GAE/100g dry weight)

Control (shaker extraction) 30.12 ± 0.05b

50% Ethanol, ultrasonic 20 minutes 36.32 ± 3.90a


50% Ethanol, ultrasonic 40 minutes 35.42 ±0.09a

Table 1 Ethanol concentration at 50% and ultrasonic extraction time on

total phenolic content of mulberry leaves.

In Table 2, effects of ethanol concentration of 80%

and ultrasonic times on the total phenolic contents were

shown. The test results were obtained from the tests with

three sets of ultrasonic times (10, 20 and 30 minues). It was

found that total phenolic contents will increase with the

increasing of ultrasonic extraction time (p≤0.05). The

highest amount of total phenolic content was found when

applied ultrasonic time at 40 minutes. Moreover, the total

phenolic contents were higher than the control variable

(p≤0.05). The results agreed with the finding [21] who

suggested that using ultrasonic cound provide higher total

phenolic contents of mulberry leaves compared to the

conventional extraction methods.

Condition of extraction Total phenolic compounds

(mg GAE/100g dry weight)

Control (Shaker extraction) 27.50 ± 0.08b

80% Ethanol, ultrasonic 20 minutes 27.39 ± 0.05b

80% Ethanol, ultrasonic 30 minutes 29.33 ± 0.25ab



total phenolic contents of mulberry leaves.

Control



Retention time 4.58, Peak area 210650






In this study, the samples were ultrasonic extraction

time at 20, 30 and 40 minues. The time of control sample

was controlled at the 60 minues. The effect of extraction

time on antioxidant activity were shown in Table 3. The

highest of antioxidant activity at ultrasonic time at 40 min,

then higher than control (p≤0.05). Moreover, the ultrasonic

extraction time was increased from 20 to 40 minues, the

increasing of antioxidant activity of mulberry leaves. The

ultrasonic-assisted could increase the activity of some

enzymes such as pectinase, wich can disintegrate cell wall

and membranes and therefore promote the passage of total

phenolic contents. Therefore, ultrasonic-assisted technique

can provide high antioxidant activity of mulberry leaves.

The effect of ultrasonic time on the antioxidant

activity of mulberry leaves under this study was examined

with three different ultrasonic times (20, 30 and 40 minues)

at 30 °C; with the soaking time of 60 minutes. The

experimental results of this test were depicted in Table 4. It

can be seen that the highest antioxidant activity was

obviously achieved with applied ultrasonic time at 40

minutes. However, when the ultrasonic time was increased

from 20 to 40 minutes, the values of antioxidant activity

had significant difference. In addition, the antioxidant

activity of the samples was higher than one of the control

variable (p≤0.05). As well as research of [22] found that

extraction time had effected on antioxidant activity of

devils horse whip.

The results shown that 50% ethanol concentration can

provide total phenolic contents and antioxidant activity of

mulberry leves. Therefore, use 50% ethanol concentration

can reduce the cost of the experiment compaired with 80%

ethanol concentration.

Condition of extraction % Redical scavenging

Control(shaker extraction) 24.73 ± 2.34c



50% Ethanol, ultrasonic 40 minutes 43.89 ±3.96a


antioxidant activity of mulberry leaves.

Condition of extraction % Redical scavenging

Control(shaker extraction) 22.23 ± 2.49c





antioxidant activity of mulberry leaves.

4. Conclusions

This research was to investigate effects of using

ultrasonic-assisted extraction on bioactive compounds of

mulberry leaves in comparison with conventional extraction

methods. The experimental results show that the ultrasonic-

assisted extraction provides highest total phenolic contents

and DPPH scavenging activity of mulberry leaves when

compared with the controlled sample galic acid (p≤0.05).

Increasing the extraction time would give result in higher

amount of total phenolic contents and DPPH scavenging

activity. In addition, the ultrasonic extraction with 50%

ethanol concentration for 40 minutes provides the highest

total phenolic contents and DPPH scavenging activity.

Acknowledgements

This research was financially supported by the Faculty

of Engineering, Mahasarakham University, Thailand.

References

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products: Gumushane pestil and kome. Turkish Journal of

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[2] THABTI, I., ELFALLEH, W., HANNACHAI, H., FERCHICHI,

A. & CAMPOS, M.D.G. Identification and quantification of

phenolic acids and flavonol glycosides in Tunisian Morrus species

by HPLC-DAD and HPLC-MS. Journal of Functional Foods,

2012, 4, p. 367-374.

[3] ANDALLU, B. AND VARADACHARYULU, N.C.

Gluconeogenic substrates and hepatic gluconeogenic enzymes in

strepzotocin-diabetic rats: effect of mulberry (Morus indica L.)

leaves. Journal of Medicinal Food. 2007, 10, p. 41-48.

[4] DOI, K., KOJIMA, T., MAKINO, M., KIMURA, Y. AND

FUJIMOTO, Y. Studies on the constituents of the leaves of Morus

alba L. Chemical & Pharmaceutical Bulletinn, 49, p. 151-153.

[5] GOUKI, M., KENSAKU, T., KOJI, W. TOMOYUKI, O.K.I.,

MAMI, M., IKUO, S. Evaluation of antioxidant activity of

vegetables from Okinawa Prefecture and determination of some

antioxidative compounds. Food Science and Technology

Research, 2006. 12, p. 8-14.

[6] TOMA, M. VINATORU, M. PANIWNYK, L. MASON, T.J.

Investigation of the effects of ultrasound on vegetal tissues during

solvent extraction. Ultrason Sonochem. 2001, 8, p. 137-142.

[7] VINAYAK, U., SANDEEP, R. P. AND HARSHA, V. H. Effect of

method and time of extraction on total phenolic content in

comparison with antioxidant activities in different parts of

Achyranthes aspera. Journal of King Saud University Science.

2015. 27, p. 204-208.

[8] DU, F.Y., XIAO, X.H. AND LI, G.K. Application of ionic liquids

in the microwave-assisted extraction of trans-resveratrol from

Rhizina Polygoni Cuspidati. Journal of Chromatography A. 2007,

1140, p.56-62.

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S. AND ADLER-NISSEN, J. Production of specific-structureed

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[10] HROMADKOVA, Z. AND EBRINGEROVA, A. Ultrasonic

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[11] SPORRING, S., BOWADT, S. SVENSMARK, B. AND

BJORKLUND, E. Comprehensive comparison of classic Shoxlet

extraction with Soxtec extraction, Ultrasonication extraction,

Supercritical fluid extraction, microwave assisted extraction and

accelerated solvent extraction for the determination of

polychlorinated biophenyls in soil. Journal of Chromatography A,

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[12] KIMBARIS, A. C., SIATIS, N. G., DAFERERA, D. J.,

TARANTILIS, P. A., PAPPAS, C. S. AND POLISSIOU, M. G.

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methods for the isolation of sensitive aroma compounds from

garlic (Allium sativum). Ultrasonics Sonochemistry, 2006. 13, p.

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[13] CHEN, M., ZHAO, Y. AND YU, S. Optimisation of ultrasonic-

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L. AND XIAO-HUI, Y. ultrasound extraction of polysaccharides

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The study of phenolic profiles of raw apricots and apple and their

purees by HPLC for the evaluation of. apricot nectars and jams

authenticity. Food Chemistry. 2005. 91, p. 373-383.

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M. AND OGNJANOV, V. Analysis and characterization of

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[21] CONTINI, M., BACCELLONI, S., MASSANTINI, R. AND

ANELLI, G. E. Extraction of natural antioxidants from hazelnut

(Corylus avellana L.) shell and skin wastes by long maceration at

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[22] LUQUE DE CASTRO, M. AND GARCIA-AYUSO, L. Soxhlet

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Bibliography

Pianpan Supakot received her master

degree in Food Technology from

Ubonratchathani University, Thailand,

in 2012. She is currently a lecturure in

Burirum Rajabhat University. Her

research interests include food

processing, drying, analysis bioactive

compounds agricultural products.

Jittawan Kubola received her Ph.D in

Food Technology from Mahasarakham

University, Thailand, in 2012. She is

currenly a lecturure in Burirum

Rajabhat University, Thailand. Her

research interests include bioactive

compounds in agricultural products.

Chuleeporn Bungthong

received

her master degree in Food Science

and Technology from Burapha

University, Thailand, in 2010. She is

currenly a lecturure in Burirum

Rajabhat University, Thailand. Her

research interests include postharvest

of agricultural products.


Analysis and Characterization of the Nutrient

Concentration of Thatluang Marsh Attributed

to Wastewater Discharges from

Vientiane City, Lao PDR

Somphone Inkhamseng1,*

and Veokham Vilaysane2

1, 2 Water Resources Engineering Department, Faculty of Engineering, National University of Laos,

Vientiane Capital, Lao PDR

[email protected] 1,*

Abstract. The analysis and characterization of the nutrient

concentration of Thatluang Marsh is needed in order to

evaluate the ability of a natural marsh to assimilate waste as

well as to develop management schemes to maintain and

enhance the integrity of the marsh. This study is mainly

concerned with the analysis and characterization of the

temporal and spatial variation of nutrient concentrations in

Thatluang marsh (i.e., a natural marsh) as well as its major

tributary rivers and canals located in the Makhiao river

basin. The marsh area is about 20 km2 and mainly occupied

by residential areas and some agricultural areas. Monthly

nutrient concentration and daily water discharge observed

from October 2011 to August 2012 were used in this study. In

particular, the nutrient data from the marsh and major

tributary rivers and canals were sampled for nitrogen and

phosphorus species in the form of ammonium-nitrogen (NH4-

N), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), total

nitrogen (TN), phosphate-phosphorus (PO4-P) and total

phosphorus (TP). The nutrient concentrations at Kae canal

were the highest compared to the other stations during the

study period with values of 16.04 mg/l for TN and 14.80 mg/l

for TP. The NH4-N concentration at Kae canal and the outlet

sometimes exceeded the water quality for irrigation water by

FAO standards. The results indicate that relatively high

amounts of NH4-N emanate from the municipal area. The

NH4-N, NO2-N and NO3-N concentrations were low during

the entire observation period at Khae river and Papiao river,

compared to Kae canal. The low concentrations might be

attributed to the low population density upstream of these

sampling points. The TN and TP loads at the outlet of the

marsh were higher than the sum of the loads at the other

gauging points.

Keywords:

Makhiao river basin, nitrogen, nutrient, phosphorus,

Thatluang marsh

1. Introduction

Vientiane, the capital city of Lao PDR with its

population of 616,000, has a unique waste water treatment

system. Most of the wastewater discharges from factories

and households in Vientiane city directly goes into

Thatluang marsh, whose water surface area is about 20

km2. The water undergoes natural purification processes in

Thatluang marsh, before it is discharged to Mekong river

through Makhiao river.

However, it is seriously concerned that the

purification capacity of Thatluang marsh may be declining

because of recent shrinkage of its water surface area. The

expansion of arable land by the local people and the

construction of building by Lao government are considered as

the major causes of the shrinkage of the marsh. It is also

concerned that the rapid shrinkage of the marsh greatly alters

the natural ecosystem of the marsh and consequently causes

various environmental problems around the marsh and the

downstream areas.

In order to seek an appropriate management plan of the

marsh coping with both population increase and

environment protection, it is necessary to grasp the current

movement of the water and the contaminants flowing through

the marsh. It is important to evaluate the current purification

capacity of the marsh accurately.

2. Methods

2.1 Sampling Point

The sampling points where water samples were taken

from the rivers and the canal were selected near Thatluang

marsh, which is located in the southern part of Makhiao

watershed. The locations of the canal and rivers in which the

samples were taken and the land covers around the marsh are

shown in Fig. 1. Samples were collected from Kae canal,

Papiao river and Khae river that flow into Thatluang marsh.


Kae canal locates at the northwest of Thatluang marsh and

both sides of the canal consist of urban areas with factories

and households. Samples were also taken at the outlet of

Thatluang marsh, which is about 15 km west of

Vientiane downtown.

Fig. 1 Location of the canal and the rivers in which the samples

were taken and the land cover around the marsh.

2.2 Hydrological Observation

The study period of the present study covers 11 months

from October 2011 to August 2012. At the gauging stations in

the selected rivers and the canal, the water depth was

measured daily by a scale and the flow velocity was measured

daily by a float. The cross section areas of the flow were

calculated from the observed water depth and the shape of the

river cross section surveyed beforehand. The discharge was

calculated as a product of the cross section area and the flow

velocity. Water samples were taken once a month directly

from the water surface by a 500 ml clear plastic bottle at the

gauging stations. 44 river water samples were taken during

study period.

2.3 Analytical Methods

The After the immediate pre-treatment to prevent

possible quality changes, the samples were kept at about 4°C

until being analyzed in the laboratory at Water Quality

Monitoring center, Ministry of Agriculture and forestry,

Vientiane. The samples were analyzed for total nitrogen (TN),

ammonium-nitrogen (NH4-N), nitrate-nitrogen (NO3-N),

nitrite-nitrogen (NO2-N), phosphate-phosphorus (PO4-P) and

total phosphorus (TP) by a spectrophotometer (Hach, Model

DR/4000U) and a digester boy (Model TNP-1).

3. Results and Discussions

3.1 Flow Characteristics

The flow characteristics of the 4 gauging stations for the

period from October 19, 2011 to August 31, 2012 were

examined. Changes in the discharge at the gauging stations are

shown in Fig. 2. During the study period, the discharge varied

in the range from 0.36 to 5.19 m3/s, from 0.09 to 2.21 m

3/s,

from 0.03 to 1.29 m3/s and from 0.03 to 0.75 m

3/s for the

outlet of Thatluang marsh, Kae canal, Papiao river and Khae

river, respectively.

Fig. 2 Change in discharge flows at the gauging stations.

3.2 Nutrient Concentration Level

Table 1 and Table 2 show the mean and the range of the

observed nutrient concentrations. The mean is the simple

arithmetic average and is not weighted by the corresponding

discharge. The TN concentration at the outlet varied in the

range between 3.00 and 13.06 mg/l and the mean TN

concentration was about 80% of that in Kae canal. The NO2-N

and NO3-N concentrations at all stations were not so high

compared to the maximum concentration for drinking water

recommended by USEPA (1996) and WHO (1993). The

NH4-N concentration at Kae canal and the outlet sometimes

exceeded the water quality for irrigation water presented by

FAO (website). It is suggested that a relatively higher amount

of NH4-N flowed out from the municipal area and was

detected at the sampling station in Kae canal and the outlet.

The PO4-P concentrations at all station were high

compared to the international standards for drinking water and

water quality for irrigation water as mentioned above. It is

considered that the PO4-P concentration would be elevated by

effluents from agricultural land and municipal areas. TP

concentrations at the outlet stayed in the range between 1.40

and 10.60 mg/l and the mean TP concentration was about

69% of that in Kae canal.


Parameters

(mg/ L)

Outlet of the Marsh

Mean Range

NH4-N 1.59 0.10-5.60

NO2-N 0.07 0.02-0.18

NO3-N 0.84 0.15-1.70

TN 8.64 3.00-13.06

PO4- P 2.00 0.50-5.80

TP 5.42 1.40-10.60

Table 1 The mean and the range of the observed nutrient

concentrations at the outlet of the marsh .

Parameters

(Unit)

Kae Cannel Pa Piao River Khae River

Mean Range Mean Range Mean Range

NH4-N 2.33 0.29-5.40 0.45 0.10-0.93 0.35 0.10-0.80

NO2-N 0.06 0.02-0.11 0.16 0.01-0.34 0.06 0.02-0.14

NO3-N 0.83 0.10-2.40 1.10 0.20-2.00 0.63 0.20-1.80

TN 10.87 3.66-16.04 2.48 1.03-4.62 1.36 0.74-2.90

PO4- P 2.35 0.49-5.00 0.82 0.08-2.80 0.79 0.01-2.80

TP 7.90 2.10-14.80 2.08 0.26-5.10 1.95 0.18-8.10

Table 2 The mean and the range of the observed nutrient

concentrations at the Kae cannel, Pa Piao river and Khae

river.

3.3 Seasonal Variation in Nutrient

Concentrations

Several interesting facts were revealed by the in-situ

observation in the present study. For example, the nitrogen

and phosphorus concentrations showed different

characteristics in their seasonal variation. The variation in the

concentrations in nitrogen and phosphorus species during the

study period is shown in Fig. 3 – Fig. 6. The highest TN

concentration at Kae canal was observed to be 16.04 mg/l in

January 2012. While at Khae river and Papiao river, the

highest TN concentration were observed to be 2.90 and 4.62

mg/l in October 2011 and in May 2012 respectively. For the

TN concentration peak in May at Papiao river, it is considered

that nitrogen accumulated in the watershed and the stream bed

during the dry season was flushed by the first runoff in the

beginning of the rainy season. The NH4-N, NO2-N and NO3-N

concentrations were low during the whole observation period

at Khae river and Papiao river, compared to Kae canal. The

lower concentrations might be attributed to the lower

population density in the upstream of these sampling points.

On the other hand, the TP concentrations at Khae river,

Papiao and the outlet of the marsh were high in October. It is

suggested that higher coverage of agricultural land in the

upstream of the sampling points and fertilizer utilized by

farmers in dry season may contribute the TP concentration

peak in October. The maximums of the PO4-P concentration

were recorded to be 5.8, 5.0, 2.8 and 2.8 mg/l in April 2012 at

the outlet, Kae canal, Papiao river and Khae river,

respectively. The sharp increase in the phosphorus species

corresponded to the first small rise of the discharge after the

low flow period. It is suggested that the first runoff after the

dry season took the accumulated in the marsh and on the river

bed to the river water and consequently brought about the

sharp increase of the phosphorus concentrations.

Fig. 3 The variation in the concentrations in nitrogen and

phosphorus at the outlet of Thatluang marsh.


phosphorus at Kae canal.


phosphorus at Papiao river.


phosphorus at Khae river.


3.4 Estimation of nutrient loads

The seasonal variations in the nitrogen and phosphorus

loads were significantly governed by the changes in the

discharge. The highest loads at all stations occurred in August,

apparently because of a large amount of discharge carrying

the nutrients.

During the study period (11 months), the TN and TP

loads flowed through each observation station were calculated

roughly to be 278, 153, 19, 7 tons and 179, 136, 13 and 11

tons at the outlet, Kae canal, Papiao and Khae river,

respectively.

4. Conclusions

To grasp the current movement of the water and the

contaminants flowing through Thatluang marsh, the water

flow and the nutrient concentrations in major inflow rivers and

canal into the marsh were measured from October 2011 to

August 2012.

The mean TN concentration at the outlet of the marsh

was about 80% of that in Kae canal, while the mean TP

concentration at the outlet of the marsh was about 69% of that

in Kae canal. The NH4-N concentration at Kae canal

sometimes exceeded the water quality for irrigation water

given by FAO. It is suggested that a relatively higher amount

of NH4-N flowed out from the municipal area. The PO4-P

concentrations at all stations were also high compared to the

water quality for irrigation. It is considered that the PO4-P

concentration would be elevated by effluents from agricultural

land and municipal areas. The maximums of the PO4-P

concentration were recorded as 5.8, 5.0, 2.8 and 2.8 mg/l in

April 2012 at the outlet, Kae canal, Papiao river and Khae

river, respectively. The sharp increase in the phosphorus

species corresponded to the first small rise of the discharge

after the low flow period.

The changes in the nutrient loads were governed by the

changes in the discharge, clearly due to a large amount of

discharge carrying the nutrients. The TN and TP loads at the

outlet of the marsh were higher than the sum of the loads at

other three observed stations at the upstream of the marsh.

5. Acknowledgments

This study was supported by fund of the Kurita Water

and Environment Foundation, KWEF of Japan. The authors

would like to express sincere thanks to all students who

supported this study.

References

[1]

FAO,http://www.fao.org/docrep/003/t0234e/T0234E01.

htm#ch1-

4and/or,http://www.fao.org/docrep/003/t0234e/t0234E0

0.htm

[2] USEPA (1996), “Quality criteria for water. EPA 440 /

5-86-001”, U.S. Environmental Protection

Agency,Washington DC, USA.

[3] WHO (1993), Guidelines for drinking water quality.

World Health Organization, Geneva, Switzerland.

[4] Iida T. et al (2004) Seasonal variations in nutrient loads

in the Mekong River at Vientiane, Lao PDR.

[5] Iida T. et al (2007) Seasonal variation in nitrogen and

phosphorus concentration in the Mekong River at

Vientiane, Lao PDR.

Bibliography

Somphone INKHAMSENG was born in Vientiane, Laos in

February 1965. He received this bachelor and master degree

in Surface Water Hydrology from Saint Petersburg, Russia in

1992 and his doctoral degree in Environmental Engineering

from the University of Philippines, the Philippines. He is

currently an Acting Head of Department of Water Resources

and Development in Faculty of Water Resources, National

University of Laos. His research interests are water

engineering, water quality modeling and environment

management.


Sustainable Polymers: From Recycling of Non-Biodegradable to

Renewable Resources Composites and Foams Yottha SRITHEP1*, Lih-Sheng TURNG2, John MORRIS1, Dutchanee PHOLHARN3, and Onpreeya VEANGIN1

1 Manufactuing and Materials Research Unit, Faculty of Engineering, Mahasarakham University, Maha Sarakham 44150,

Thailand 2 Polymer Engineering Center, Department of Mechanical Engineering, University of Wisconsin–Madison, Madison,

WI 53706, USA 3 Department of Chemistry, Faculty of Science, Rajabhat Mahasarakham University, Maha Sarakham 44000, Thailand

[email protected]*

Abstract Sustainable polymers and composites provide possibility to be environmental impact free materials for the future applications. These materials could be used as recycling post-consumer plastic products, biodegradable polymers made from renewable resources, and reducing the materials used by making either foamed parts or stronger polymer composites. Using natural cellulose fibers as fillers for biodegradable polymers would also result in fully biodegradable green composites and help to reduce the matrix polymer material used. It is hoped that these approaches will help to accelerate and facilitate recycling and the reduction of polymers, as well as promote an increased adoption of polymers and composites from renewable resources. More details on the aforementioned topics have been presented in this paper.

Keywords: Sustianable polymers, recycling, biodegradable plastics, renewable resources, composites and foams

1. Introduction Since 1976, plastics have become the most widely used

material in the world [1]. Today, approximately 100 million tons of plastics and polymeric materials are produced worldwide every year. Plastics are used in the appliance, automotive, construction, electronics, packaging, and transportation industries, as well as in a wide array of consumer products. Human society has gone through periods called the Stone, Bronze, Copper, Iron, and Steel Ages based on the material that was utilized the most during that time. At present, the total volume of plastics produced worldwide has surpassed that of steel, copper, and aluminum combined by volume and continues to increase. Without a doubt, we have entered the Age of

Plastics [2]. Among all polymers produced, five major synthetic polymers account for over 90% of the plastics produced worldwide—polyethylene (PE), poly(ethylene terephthalate) (PET), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC)—all of which are produced from “non-renewable” resources such as petroleum (crude oil), natural gas, and coal [2].

The words “polymers” and “plastics” are interchangeably used in this paper. A more precise definition of “plastics” is polymeric compounds mixed with some kind of additives for cost reduction, ease of processing, and enhanced performance. Polymers are rarely used alone and most, if not all, of the end products that reach consumers are plastics.

These plastics are very durable, thus leading to the increasingly worrisome issue of disposing of these plastic products after consumers have used them. For example, when we eat a sandwich which is wrapped in plastic, where does the plastic wrap go after we finish the sandwich? It goes into landfills, of course, leaving many people to wonder if we have gone too far in our use of plastics and the non-biodegradable waste they produce.

2. Recycling

One solution to decrease plastic waste is to recycle it. Similar to organic materials, plastics degrade depending upon the passage of time and exposure to thermal and mechanical heat generated during and after processing [3]. Recycled plastics must retain the charac-teristics of their virgin material [4]. To compensate for possible deterioration in properties through recycling, additives can be incorporated to improve the recycled material’s properties [4]. Moreover, plastic waste should be recovered as a single-material. Different polymers are usually mutually incompatible; that is, different macro¬molecules


repel each other and phase separation occurs. The mechanical properties of incompatible polymers are usually inferior. The surface structure following phase separation is also poor. If the second phase of the polymer is uniformly dispersed in the first phase, its particles can be bound to the first by adding compatibilizers in order to improve its properties [4]. Also, reprocessing of mixed plastics with different melting points causes degradation, leading, in turn, to deterioration in physical properties.

For example, PET and PVC cannot be melt-processed together because PVC burns at PET’s melt temperature (270°C). If the same mixture is processed at 170°C, which is suitable for PVC, the PET would remain solid, thus preventing the desired mixing [5]. Items such as PET soft drink bottles or natural HDPE milk bottles are abundant in the United States, where curbside collection and drop-off centers are common, thus providing ideal feedstock. In addition, recycled materials can also be blended with enough virgin resin so as to attain the required end properties or as an inner layer in co-extrusion or co-injection molding processes [4],[6].

The degradation of condensation thermoplastics, via hydrolysis, alcoholysis, thermal cleavage, and other mechanisms, is known to be severe. Those mechanisms decrease the range of acceptable applicationsdue to the loss of molecular weight in the recycled materials. One practical and cost-competitive approach uses a chain extender (CE) while reclaiming the recycled materials to increase the molecular weight. Chain extension technology uses nonlinear chain extension. That is, epoxy-functional styrene–acrylic-based, or styrene-free–acrylic-based reactive polymers are used to extend the initial polymer with long chain branched structures. Fig. 1 shows schematically the multi-functional chain extension concept [7].

Fig. 1 Schematic representation and the principle of chain extension [7]

The recycling of plastics, although extremely useful in terms of cost and raw plastic reduction, sometimes offers a perfect excuse to overlook the inevitable negative result of synthetic polymer production [7]. Recent advances in genetic engineering, natural fiber development, and composite sciences offer innovative opportunities to improve materials from renewable resources, which can be biodegradable and recyclable, to finally obtain sustainable sources [8].

3. Renewable Resources Another solution to plastic waste is tomake plastics

degrade at an accelerated pace after they have been discardedor toproduce plastics from renewable resources. Biodegradable plastics, designed to decompose through the action of living microorganisms, are an alternative to conventional plastics when recovery or recycling are impractical [9]. Biodegradable polymers can be further broken down into two main groups: renewable and non-renewable polymers. Essentially, renewable biodegradable polymers utilize a renewable resource (e.g., a plant by-product) in the development of the polymer, rather than a non-renewable (e.g. petroleum-based) resource. A renewable material can be reproduced again and again. For example, when we use plantation wood to produce paper we can plant more trees to replace it. Obviously, long-term research and development (R&D) focuses on renewable and biodegradable polymers, but initial R&D work on petroleum-based biodegradable polymers has shed insight on many of the initial bio¬degradable products. The use of biodegradable plastics from renewable sources is not only a promising solution to the growing environmental issues by conserving limited non-renewable resources (petroleum) and reducing CO2 emissions, but is also an excellent opportunity for agricultural industries around the world to produce raw materials and feedstock for this thriving industry [10]. It could be argued that the current use of polymer materials is unsustainable. Therefore, it is necessary to seek a sustainable approach to the manufacturing and use of these materials. At present, their cost prevents the wide use of biodegradable plastics [5]. However, the spiraling costs of petroleum-based polymers and the scaled-up pro¬duction of polymers from renewable resources will make the latter more competitive in the foreseeable future. Fig. 2 illustrates the classification of biodegradable polymers.

4. Composites and Foams

Our aim for the future must be to design products that can minimize the use of materials and energy in the manufacturing and usage stages and minimize waste and emission to the environment. The goal of this study is to minimize the materials used through micro-cellular foams and enhancement of material properties such as increasing


Biodegradable polymer

Petro-based synthetic

− Aliphatic polyester

− Aliphatic-aromatic polyester

Biodegradable polymer blends

Blends of different biodegradable polymers

Renewable resource-based

− PLA polymer (from corn)

− Cellulosic plastics

− Polyhydroxylalkanoate (PHA)

− Bacterial bio-plastics

Fig. 2 Classification of biodegradable polymers [8]

the degree of polymer crystallinity and introducing reinforcing fillers in polymer composites.

Microcellular foam is a polymeric foam with bubble sizes of 100 microns or less and cell densities higher than 1 × 106 cell/mm3. Microcellular foams are also sought for weight reduction in very thin films and sheets and for improved impact strength without significant mechanical property changes [11]-[14]. Three basic steps of producing microcellular foams are mixing/saturation, cell nucleation, and cell growth (Fig. 3) [15]. Microcellular foams have been widely used in various applications such as cushioning, insulation, packaging, and absorb¬ency. Foams with interconnected pore structures have recently been studied for their appli¬cations in tissue engineering as scaffolds for cell attachment and growth [15].

A composite material is a material system composed of two or more physically distinct phases. Composites can be designed that are very strong and stiff, yet very light in weight, giving them greater strength-to-weight and stiffness-to-weight ratios [17]. Weight reduction is a key consideration in many industries; notably, the aerospace and automotive industries. A lighter vehicle could mean better fuel efficiency [18].

Natural fibers can also be used as reinforcing fillers for composites as harvested. A large range of natural fibers have been successfully used in composites in recent years, including jute, hemp, kenaf, ramie, sisal, flax, and sugar cane bagasse fibers. They have low densities and high strengths and stiffnesses relative to their densities. Furthermore, theyare low cost, biodegradable, and nonabrasive, unlike other reinforcing fibers [19]. However, a disadvantage of natural fibers is that they are incompatible with typically hydrophobic polymers due to their hydrophilicnature, thus making it challenging to use them as reinforcements in polymers. In addition, insufficient wetting of natural fibers by the polymer matrix has been shown to lower the tensile strength and stiffness of

a composite, as a poor interface cannot effectively transfer the stress from the polymer matrix to the fibers. Moisture absorption is another problem of natural fibers, as the moisture presence causes voids, thus reducing the strength of the composite. The moisture content will vary depending on the relative humidity or wetting of the composite. Moisture also interferes with the melt compounding and processing of the composites since processing temperatures on the order of 180 to 200°C are necessary. When the moisture is removed from the natural fibers, they become brittle, thereby losing their effectiveness as reinforcements [20].

The production of nanoscale fibers and their application in composite materials have gained increased attention due to their high strength and stiffness, combined with being low weight, biodegradable, and renewable[21]. It is necessary to breakthe cell plant materials into nanoscale fibers in order to achieve the reinforcing effects of the plant material. Table 1 shows that as the size of the filler component becomes smaller, the tensile strength and modulus become greater. The modulus of elasticity of a perfect crystal of native cellulose was measured by different authors and is estimated to be between 130 and 250 GPa. The tensile strength of the crystal structure was assessed to be approximately 0.8 to 10 GPa [22]. However, the separation of plant fibers into smaller elementary constituents has typically been a challenging process to perfect, requiring high amounts of energy [22], [23].

Since many polymers are composites of amorphous and crystalline phases, the amount of each phase will determine its final properties. Other details such as the nature of the crystal structure and the size and number of spherulites also play a role. Orientation of crystalline polymers can increase the degree of crystallinity in a polymer and improve its thermal stability as well as its mechanical properties [24]. Increasing the degree of crystallinity improves certain mechanical properties as well as the chemical resistance of the material.


Fig. 3 Schematic of the microcellular foaming process [16]

Disintegration Process Component Modulus of Elasticity Tensile Strength

Pulping Wood 10 GPa 100 MPa

Mechanical/chemical dissolving Fiber 40 GPa 400 MPa

Mechanical/chemical dissolving Fiber (smaller size) 70 GPa 700 MPa

Mechanical/chemical dissolving Crystal structure 130–250 GPa 800–10000 MPa

Table 1 Interrelation among structure, disintegration process, obtained component, modulus of elasticity, and tensile strength of natural fibers [22]

5. Conclusions

Sustainable polymers and composites have the potential to reduce negative impacts on the environment and future generations through (1) recycling post-consumer plastic products,(2) using biodegradable polymers made from renewable resources, and(3) reducing the materials used by making either foamed parts or stronger polymer composites. Using natural cellulose fibers as fillers for biodegradable polymers can also result in fully biodegradable green composites and help to reduce the matrix polymer material used. It is hoped that these approaches will help to accelerate and facilitate recycling and the reduction of polymers, as well as promote an increased adoption of polymers and composites from renewable resources.

References

[1] Carole TM, Pellegrino J, Paster MD. Opportunities in the industrial biobased products industry. Applied biochemistry and biotechnology 2004;115(1):871-85.

[2] Stevens ES. Green plastics: An introduction to the new science of biodegradable plastics: Princeton Univ Pr; 2002.

[3] Schnabel W. Polymer degradation, principles and practical applications1986.

[4] Brandrup J. Recycling and recovery of plastics: Hanser Verlag; 1996.

[5] Khait K. Recycling, Plastics. Encyclopedia Of Polymer Science and Technology 2003.

[6] Srithep Y, Miller B, Mulyana R, Villarreal MG, Castro JM. A study on material distribution and mechanical properties in co-injection molding. Journal of polymer engineering 2008;28(8):467-84.

[7] Frenz, editor Multifunctional polymers as chain extenders and compatibilizers for polycondensates and biopolymers. ANTEC; 2008.

[8] Mohanty AK, Misra M, Drzal LT. Natural fibers, biopolymers, and biocomposites: CRC; 2005.

[9] Khait K. Recycling, Plastics. Encyclopedia Of Polymer Science and Technology2003.

[10] Satyanarayana KG, Arizaga GGC, Wypych F. Biodegradable composites based on lignocellulosic fibers--An overview. Progress in Polymer Science 2009;34(9):982-1021.


[11] Throne JL. Thermoplastic foam extrusion: an introduction: Hanser Gardner Pubns; 2004.

[12] Xu J. Microcellular Injection Molding: Wiley; 2010.

[13] Colton J, Suh N. The nucleation of microcellular thermoplastic foam with additives: Part I: Theoretical considerations. Polymer Engineering & Science 1987;27(7):485-92.

[14] Zhu B, Zha W, Yang J, Zhang C, Lee LJ. Layered-silicate based polystyrene nanocomposite microcellular foam using supercritical carbon dioxide as blowing agent. Polymer 2010;51(10):2177-84.

[15] Hossieny NJ. Morphology and properties of polymer/carbon nanotube nanocomposite foams prepared by super critical carbon dioxide 2009.

[16] Siripurapu S. Blend-and surface-assisted foaming of polymers with supercritical carbon dioxide.2003.

[17] Groover MP. Fundamentals of modern manufacturing: Materials processes, and systems: Wiley-India; 2007.

[18] Gupta M. Polymer Composite: New Age International; 2007.

[19] Saheb DN, Jog J. Natural fiber polymer composites: a review. Advances in Polymer Technology 1999;18(4):351-63.

[20] Baillie C. Green composites: polymer composites and the environment: CRC; 2004.

[21] Siró I, Plackett D. Microfibrillated cellulose and new nanocomposite materials: a review. Cellulose 2010;17(3):459-94.

[22] Zimmermann T, Pöhler E, Geiger T. Cellulose fibrils for polymer reinforcement. Advanced engineering materials 2004;6(9):754-61.

[23] Lu J, Wang T, Drzal LT. Preparation and properties of microfibrillated cellulose polyvinyl alcohol composite materials. Composites Part A: Applied Science and Manufacturing 2008;39(5):738-46.

MIJET

ISSN 2408-1957

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Mahasarakham International Journal of Engineering Technology

MIJET

Volume 1, Number 1, January – June 2015

http://mijet.engineer.msu.ac.th

ISSN 2408-1957


Contents Research Papers ______________________________________________________________________________ Abrasive Wear Resistance of Hypoeutectic 16 wt% and 26 wt% Cr Cast Irons with Molybdenum S. Inthidech, Y. Matsubara …………………………..……………………………………………………………. 1 Application of Microcontroller for Controlling HHO Dry Cell in Small Trucks W. Sa-ngiamvibool, A. Aurasopon …………………….……………………………….…………………………. 10 Effects of Extraction Factors on Total Phenolic Compounds and Antioxidant Activity in Mulberry Leaves P. Supakot, J. Kubola, C. Bungthong …………………………….…………………………………………….... 14 Analysis and Characterization of the Nutrient Concentration of That Luang Marsh Attributed to Wastewater Discharges from Vientiane City, Lao PDR S. Inkhamseng, V. Vilaysane …………………………………..……………………………………..…………… 20 Review Paper ______________________________________________________________________________________________ Sustainable Polymers: From Recycling of Non-Biodegradable to Renewable Resources Composites and Foams Y. Srithep, L. Turng, J. Morris, D. Pholharn, O. Veangin ……...………………………………………………… 24

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