paper mill sludge

Separation and Purification Technology 26 (2002) 295–304

Synthesis and characterization of activated carbon andbioactive adsorbent produced from paper mill sludge

N.R. Khalili a,*, J.D. Vyas a, W. Weangkaew a, S.J. Westfall a, S.J. Parulekar a,R. Sherwood b

a Department of Chemical and En�ironmental Engineering, Illinois Institute of Technology, 10 W. 33rd Street, Chicago,IL 60616, USA

b IIT Research Institute, 10 W. 35th Street, Chicago, IL 60616, USA

Received 9 March 2001; received in revised form 15 August 2001; accepted 22 August 2001

Abstract

Adsorption capacity and bioactivity of a novel mesoporous activated carbon (IIT Carbon) and bioactive (BACIIT)catalyst produced from papermill sludge were evaluated. Conversion of paper mill sludge to useful activated carbonsand biocatalysts is a significant process since it reduces environmental problems associated with disposal of wastesludge, enhances wastewater treatment using carbons produced from industrial waste itself, and promotes conserva-tion of the naturally available primary resources currently used to make activated carbons. Analysis was conductedusing synthetic wastewater containing phenol and a commercially available activated carbon, sorbonorite 4 (used asreference carbon). Phenol removal was accomplished in batch and fluidized bed reactors containing mesoporousactivated carbon, sorbonorite 4, and the produced bioactive catalysts. Isotherm adsorption data indicated thatmesoporous activated carbon has a higher adsorption capacity and molecular surface coverage than sorbonorite 4 forphenol concentrations less than 10 mg/l. The mass transfer limitation was accounted for the lower adsorption capacityof the microporous carbon (sorbonorite 4) in dilute solutions. The fluidized bed reactor study, however, indicatedsimilar but slightly lower phenol removal capability for the produced mesoporous carbon. While phenol removalefficiency of the carbons studied was in the range 65–70%, the produced bioactive catalysts were able to remove upto 97% of phenol during first few hours of operation. These results suggest that mesoporous carbon will feasibly bea good substitute for other commercially available activated carbons produced from natural resources, not only inphysical adsorption processes, but also in fluidized bed bioreactors (FBB), used in biodegradation processes. © 2002Elsevier Science B.V. All rights reserved.

Keywords: Activated carbon; Phenol; Biocatalyst; Paper mill sludge

www.elsevier.com/locate/seppur

1. Introduction

The application of commercial activated carbon(AC) has been proven extensively for the removalof dissolved organics from wastewater. Activated

* Corresponding author. Tel.: +1-312-567-3534; fax: +1-312-567-8874.

E-mail address: [email protected] (N.R. Khalili).

1383-5866/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.

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N.R. Khalili et al. / Separation/Purification Technology 26 (2002) 295–304296

carbon is known to be a superior adsorbent andcatalytic support because of its excellent surfaceproperties, i.e. large surface area, porous structureand high degree of surface reactivity. Recent stud-ies have shown that ACs can be used successfullyin solvent recovery, gas refining, air purification,exhaust desulfurization and deodorization pro-cesses [1–4].

In the early seventies, some studies reportedthat proliferated bacteria in AC filters could beresponsible for the extended removal of organicsfrom wastewater. Therefore, it was suggested thatbiological elimination of dissolved organic com-pounds within activated carbon particles couldenhance the extent of organic removal by simpleadsorption process [5–7].

The mechanics of organic removal by biodegra-dation-adsorption processes on activated carbonwas further investigated using fixed and fluidizedbed bioreactors (FBB) [8–11]. The recent reviewby Sutton and Mishra [8] showed that over 80commercial media-based FBBs have been in-stalled in North America and Europe. Due to theenvironmental importance of this application, avariety of organizations such as US EPA, na-tional laboratories and non-profit research institu-tions have extensively focused on research anddevelopment activities involving AC-based FBBsystems. The single largest commercial applicationfor these is the aerobic treatment of groundwatercontaminated with petroleum hydrocarbons.

These studies have shown that fluidized bedreactors are very efficient in terms of volumetricdegradation capacity. Tang et al. [9,12] demon-strated the efficient use of the three-phasefluidized bed bioreactor in the organic (phenol)removal process. Their study also showed thatalthough the adsorptive capacity of ACs coulddecrease with repeated usage in FBB systems,these systems are still preferable over simple ad-sorption processes because the thermal regenera-tion of activated carbons in conventionaladsorption systems is very costly.

The performance of the FBBs can be signifi-cantly influenced by the characteristics and extentof biofilm formation, mass transport coefficientsand diffusion of oxygen and pollutants across thebiofilm, characteristics of the biofilm developed

on the surface of the carbon, reactor and processconfiguration (flow rate, temperature, pH), andfinally, AC and pollutant characteristics [10–14].For example, the productivity of a continuousculture can be increased if the system utilizes abiofilm instead of freely suspended microbial cells.Furthermore, a biofilm is more stable to varia-tions in flow rate and to sudden concentrationincreases of toxic substances. Fan et al. [10]showed that in FBB reactors used to removephenol from wastewater, phenol does not adsorbon the biofilm, but rather diffuses through thebiofilm. The estimated diffusion coefficient ofphenol within the biofilm was reported to varybetween 13 and 39%, based on the configurationof the system. It was also shown that the perfor-mance of the FBB system relies significantly onfactors such as bacterial accessibility for biodegra-dation, specific biofilm characteristics, systemconfiguration, organic loading, and flow rate. Theratio of biofilm surface area to culture volume hasbeen successfully demonstrated to affect the phe-nol reduction capacity of a solid support mediumusing a continuous culture of Pseudomonas putida(ATCC 11172) [15,16].

To promote adhesion and biofilm formation byPseudomonas putida, a suspended carrier shouldbe used in the bioreactors. In FBBs, however,surfaces are subjected to different shear levels,therefore, according to the specific carbon surfaceproperties, the extent of biofilm formation couldvary significantly with the characteristics of thesuspended carrier, e.g. activated carbon particles.

Most of the activated carbons used in the FBBsare microporous carbons, which are made frombituminous coal, coconut shell, wood, coal,petroleum, lignin, and lignite. In recent years thepossibility of using bio-solids for the productionof activated carbons has been explored. Jeya-seelan et al. [17], Lu [18] and Martin et al. [19]have all begun to identify processes by whichbio-solids can be transformed to AC. Our recentwork showed that carbonaceous waste materialcan be economically and efficiently converted toACs with specifically engineered surface proper-ties [20,21]. Accordingly, by controlling themethod of production, it became possible to pro-duce pure, mesoporous (80% meso and macropo-

N.R. Khalili et al. / Separation/Purification Technology 26 (2002) 295–304 297

rous structure) activated carbon from paper millsludge with surface area as high as 1020–1700m2/g. Paper mill sludge was selected for the pro-duction of activated carbon instead of biosolidssince this waste has shown less level of contami-nants and more uniform chemical composition.

The main purpose of this study was to investi-gate if the cost-effective carbon synthesized frompaper mill sludge can produce results comparable(for removal of organics from contaminated wa-ters) to those obtained for the most commonlyused carbon based sorbents (such as Sorbonorite4), and if the unique surface properties of theproduced carbons offer an economically attractivesupport system for the formation of the biofilm inFBBs. The synthesized carbons were, therefore,used as adsorbent and bio-carriers in laboratoryscale FBBs, and the extent of phenol removal fora synthetic wastewater was investigated on a bi-ofilm of Pseudomonas putida formed on the sur-face of the produced activated carbon (IITcarbon) and sorbonorite 4 (reference carbon). Thesurface characteristics and adsorption propertiesof the carbons were determined in addition toidentifying the comparative effectiveness of thesecarbons for biodegradation of phenol.

Conversion of waste sludge to carbon-basedcatalyst is a novel and environmentally friendlyprocess. It results in production of effective andcost-efficient catalyst (due to negative cost associ-ated with the raw material) from waste, and offerssignificant potential for reducing the cost ofsludge treatment, which is commonly requiredprior to its disposal. The environmental damagethat could result from uncontrolled disposal ofthe waste can also be minimized by convertingsludge to other useful products.

2. Materials and methods

The experimental section consisted of (1) pro-duction of activated carbon with a pre-definedsurface structure from paper mill sludge, (2)preparation of the culture and medium requiredfor the biodegradation study, (3) production ofactive biocatalyst (culture growth within the car-bon structure) using a specially designed bioreac-

tor, (4) analysis of the adsorption capability of theproduced carbons, and (5) determination of thekinetics of adsorption and biodegradation for theproduced carbon. The reference carbon, Sor-bonorite 4, is a commercially available carbon,which is produced from coal.

2.1. Production of a pure, mesoporous acti�atedcarbon from paper mill sludge

A pure, mesoporous activated carbon was pro-duced following the procedure developed by Wal-hof [20] and Khalili et al. [21]. The main steps inthe process for carbon production are presentedin Fig. 1. The paper mill sludge was the finalsludge produced at wastewater treatment facilityand milling processes. The chemical analysis indi-cated that sludge contains 20% ash, 34% C, 5% H,0.24% S, and 41% O2 with C/H ratio of 6.74.

Following the outlined procedure, the raw ma-terial (sludge) was first dried in an oven at 110 °Cfor 24 h, then crushed mechanically using a rollermill. Crushing provided smaller particles with in-creased surface area and also enabled more effi-cient chemical activation of the raw material.Samples were sieved after mechanical crushing toobtain a particle size smaller than 600 �m. Thisparticle size range was found to be the mostsuitable for the chemical activation process.

2.1.1. Chemical acti�ationIn the chemical activation process, the dried

material was impregnated with zinc chloride usinga ZnCl2 to sludge mass ratio of 3.5. About 100 mlof H2O was mixed with �17 g of dried, crushedand sieved sludge and a sufficient amount ofZnCl2 to maintain the specified ZnCl2 to sludgeratio. The slurry was mixed with a magnetic stir-rer at 85 °C for 8 h. Upon drying, the activated/dried sludge was crushed again into a fine powderand exposed to light and humidity for 22 h.Activation results in the production of activatedcarbons with an enhanced surface area. Theaforementioned steps promote uniform carboniza-tion reactions during the pyrolysis.

2.1.2. PyrolysisThe dried, chemically activated, and light and


humidity treated sludge was placed into a quartzreactor. The pyrolysis was carried out under aflow of nitrogen gas (70 ml/min) at 800 °C for 2h. The temperature was reached at a rate ofapproximately 20 °C per min. Nitrogen gas wasused to provide an inert atmosphere and to carryvolatile matter away from the heating zone. Uponcompletion of the pyrolysis, sample was removedfrom the reactor and crushed using mortar andpestle.

2.1.3. RinsingAfter pyrolysis, the carbonized material was

washed with 500 ml of 1.2 M HCl, followed bywashing with 500 ml of distilled water to extractresidual organic and mineral materials. The pro-duced activated carbon was then placed in adrying oven for 8–12 h (110 °C). After drying,the sample was transferred to a 20 ml vial forstorage. To produce pure activated carbonwithout any mineral substrate, the produced car-bon was treated with hydrofluoric acid (HF) for 1h, filtered, and then rinsed with distilled wateruntil a pH between 6 and 7 was achieved inwashwater. The produced activated carbon wasdried and stored in 20 ml vials prior to surfaceanalysis.

2.2. Preparation of the culture medium

The microbial species used in this study wasPseudomonas putida (c1172). This aerobic bac-terium is often used for bioremediation because ofits ability to consume phenol. This culture wasobtained from American Type Culture Collection(ATCC 11172). The freeze-dried culture was usedto prepare three different types of cultures: longterm stock culture, frozen culture to be used everymonth, and culture for inoculation and produc-tion of biocatalysts.

The cell suspensions were prepared as follows.Commercially available freeze-dried stock culturestored at −70 °C with glycerol was inoculated ina sterile Nutrient Broth (NB, 15:85) and incu-bated at 25 °C for 24 h. One portion of thissolution was stored at −70 °C and a secondportion of the solution was transferred to nutrientagar (NA, Difco) at 25 °C. The 3-day-oldcolonies of P. putida on agar were used to inocu-late 10 ml of IPM solution in a baffled flask (theIPM solution composition is provided in Table 1).Resulting suspension was held at 25 °C for 16–24h, and 1 ml of this primary culture was trans-ferred to 20 ml IPM solution and mixed for 16 hat 25 °C for the inoculation of the bioactivecarbons.

Fig. 1. Steps involved with the production of activated carbon from paper mill sludge.


Table 1Chemical constituents of the IPM solution

Chemical Amount per 1 l of solution (mg)

Phenol 500840KH2PO4

750K2HPO4

480(NH4)2SO4

60NaClCaCl2 60

60MgSO4

6FeCl3

bioreactor to study the extent of phenol removalfor each catalyst (BAC IIT and BAC Sorbonorite 4).

2.4. Adsorption isotherm study

As a substitute for industrial wastewater, aphenol solution with a concentration of 500 mg/lwas prepared. Phenol was selected for this studybecause extensive data is available on diffusivityand extent of biodegradation of phenol in FBBs.Phenol is also commonly found in waste streamsas a result of humidification processes and anthro-pogenic activities.

The adsorption isotherm parameters were de-termined for both carbons by placing 0.1 g ofeach carbon in conical flasks containing syntheticwastewater with phenol concentrations of 100,200, 300, 400 and 500 mg/l. Flasks were securedand placed on a rotary shaker for 24–48 h untilequilibrium was achieved. The liquid sampleswere centrifuged and filtered prior to measuringequilibrium concentration of phenol in each flaskusing a spectrophotometer (Spectronic 21 D, Mil-ton Roy).

2.5. Determination of the extent of phenolremo�al

2.5.1. Effect of physical adsorptionThe extent of phenol removal due to physical

adsorption was also evaluated using fluidized bedreactors containing sorbonorite 4 and IIT carbon.The fluidized bed reactors were run simulta-neously using a configuration similar to that pre-sented in Fig. 2. The adsorption study wasaccomplished by placing carbons in the reactors,adding synthetic phenol solutions, fluidizing thebed using air, and measuring phenol concentra-tion at 1 h time intervals.

2.5.2. Effect of adsorption-biodegradationThe fluidized bed reactors used to study the

effect of bioactivation of the carbons included: (a)the produced bioactive carbons (BACIIT andBACSorbonorite 4), (b) 1 ml of synthetic wastewaterdiluted with water to 100 ml, (c) 2.5 ml of 0.5 NNaOH combined with the phenol solution andphosphate buffer solution of 34 g/l having a final

2.3. Production of the bioacti�e carbons (BACIIT

and BACSorbonorite 4)

Fig. 2 demonstrates the schematic of the pro-cesses involved with the production of the biocat-alysts from IIT carbon and sorbonorite 4.

To induce biological activation, reactors werefilled with 1g of each type of carbon, and sec-ondary culture. Upon securing the mixture, oxy-gen for the bacteria growth, and IPM solutionwere passed through the reactors for 16–48 h toensure complete bacterial growth within the car-bon structure. The biologically activated carbons(BACs) were then removed from the column, oneportion was freeze dried and stored for future useand another portion was used in a fluidized bed

Fig. 2. Schematic diagram of the bioreactor used for produc-tion of biocatalysts.


pH of 7.9�0.1, and (d) phenol indicator [1 ml ofK3Fe(CN)6 (8 g/100 ml) and 1 ml of 4-aminoan-tipyrine (2 g/100 ml)]. Due to the physical andbiological characteristics of the reactors they arereferred to in this study as fluidized bed bioreac-tors (FBBs).

The concentration of phenol in each reactor wasmeasured at 1-h interval using spectrophotometer(500 nm). The reactors were equipped with a glassfrit to support the mixture (carbon and phenolicsolution). A one-way check valve was installed atthe bottom of the reactor to block the out flow ofthe solution. A condenser was attached at the topof the column to prevent any loss of phenol fromthe solution. BACs were collected at the end ofeach experiment and stored at 0 °C in the refriger-ator for further analysis.

3. Results and discussion

3.1. Characterization of the acti�ated carbons

The produced IIT carbon and Sorbonorite 4were characterized with respect to their surfaceproperties; surface area, pore volume, and theextent of micro and mesoporosity using N2 ad-sorption isotherm data. Fig. 3a and b show theadsorption–desorption isotherms obtained forthese carbons. The differences observed betweenthe isotherm shapes clearly indicate the presence ofdifferent pore structures. Also, as shown in Table2, mesoporous structure is the dominant character-istic feature of IIT carbon, while Sorbonorite 4 isa microporous carbon with the average pore di-ameter of about 13 A� . For Sorbonorite 4 meso-and microporous surface areas are comparable.Surface area related to the microporous structurein IIT carbon, however, is about three times lessthan that estimated for its meso- and macro-pores.

3.2. Determination of adsorption parameters

The adsorption isotherm curves obtained for IITcarbon and Sorbonorite 4 using a synthetic phenolsolution are presented in Fig. 4. The averagevalues obtained for q at equilibrium concentra-tions were used to construct the curves and

Fig. 3. (a) N2 adsorption/desorption isotherms for sorbonorite4. (b) N2 adsorption/desorption isotherms for IIT carbon.

estimate K and 1/n parameters. The observedstandard deviations for the measurements werebetween 0.04 and 0.06. The Freundlich model wasselected since most adsorption isotherms forwastewater processes are satisfactorily representedby this model.

A fit of the experimental data to the Freundlichmodel (Eq. (1)) leads to determination of adsorp-tion capacity of the carbons, K, and adsorptionaffinity, 1/n :

q=KC e(1/n) (1)

where q [(C0−Ce)V/mass of carbon] representsamount of phenol adsorbed per unit mass of


Table 2Surface properties of the activated carbons

Total pore Micro-pore Average poreMicro-Surface area Meso- Meso-porevolume porous(m2/g) porous surface areasurface area radius (A� )

(m2/g)structure (%) (m2/g)(cm3/g) structure (%)

1.52 25%IIT carbon 74%1092 273 808 501.08 46% 42% 5531204 505Sorbonorite 4 13

carbon, and C0 and Ce are the initial and equi-librium concentrations of phenol. The estimatesof K and 1/n are presented in Table 3. These datasuggest that carbon produced at IIT has a highercapacity (K values in Table 3) for adsorption ofphenol and stronger affinity (1/n) for phenol thansorbonorite 4. The IIT carbon also shows farbetter performance than sorbonorite 4 at lowphenol concentration (Ce less than 10 mg/l). Thehigher adsorption capacity of the IIT carbon wasrelated to its mesoporous structure and access-ibility of the pores to the adsorbate (meso-porous structure enhances diffusion–adsorptionprocesses).

3.3. Estimation of the surface co�erageparameters

To effectively compare the different carbonsand allow an accurate comparison of the basicadsorption process, isotherm graphs were con-structed based on the normalized concentrationand estimated surface coverage for each carbon.

An adsorption isotherm based on surface cover-age is a function of the size of the adsorbatemolecule and the adsorbent pore surface area.This means that one must consider the effect ofthe adsorbate molecular size to alleviate the defi-ciencies of using a mass-based solid concentrationin the isotherm correlation. As Furuya et al. [22]proposed, the surface area occupied by adsorbedmolecules, called surface coverage, can be used toaccount for the effects of molecular size. Theyproposed a conceptual model that assumes thatthe surface coverage is limited to a monolayer oforganic molecules. Based on this assumption, theextent of the surface coverage can be estimatedfrom the molecular size of adsorbents, knowingthe structure of the activated carbon.

By using the chemical bond lengths and molec-ular structure of the phenol molecule, the actualdimensions of the surface covered by one phenolmolecule and number of activated carbon ringscovered by each phenol molecule were estimatedin this study. The area of each activated carbonaromatic ring was found to be 5.25×10−20 m2.The activated carbon pore area occupied by onemole of phenol was found to be 3×105 m2

[5.25×10−20×9.5×6.02×1023 (Avogadro’snumber)].

Assuming that the adsorbed molecules form nomore than a monolayer of coverage, the mass-based solid concentration of phenol was thenconverted to a new parameter, surface coverage,S, using Eq. (2).

Fig. 4. Freundlich based adsorption isotherms for sorbonorite4.


Table 3Freundlich isotherm parameters

K 1/n Mesoporosity (cm3/g)

0.87IIT Carbon 1.130.442.5 0.28Sorbonorite 4 0.024

3.4. Determination of the extent of phenolremo�al in FB and FBB reactors

The extent of change in phenol concentrationwas determined for fluidized bed reactors contain-ing synthetic wastewater, IIT carbon, sorbonorite4 (FB reactors) and bioactivated carbons, BACIIT

and BACSorbonorite 4 (FBB reactors). As shown inFig. 6, a phenol removal efficiency of 65–70% wasobtained in FB reactors for IIT carbon and Sor-bonorite 4, respectively. The FBB reactors were,however, able to remove up to 97% (S.D.�1.2)of the phenol using either BACIIT orBACSorbonorite 4.

The overall removal efficiency of the FB reac-tors containing IIT carbon and sorbonorite 4 wasrelated to the physical adsorption on the carbons.The higher removal efficiencies observed for theFBB reactors were affiliated with the cumulativeeffect of biodegradation and physical adsorptionby biofilm and carbon structure. The lower sur-face area and higher mass transfer limitations athigher phenol concentrations were responsible forthe lower removal efficiencies obtained for the IITcarbon used in the FB reactors. The other impor-tant parameter that could have a significant im-pact on the adsorption capability of the carbons is

S=amount adsorbedadsorbed molecular area

pore surface area(2)

The amount adsorbed (mol/g) was calculatedby dividing q (mg/mg carbon) by the molecularweight of phenol (94.05 g/gmol). Fig. 5 showsadsorption isotherms obtained for the carbonsunder study using surface coverage model. Asshown, IIT carbon provided higher surface cover-age for phenol when compared with Sorbonorite4.

These results are in a good agreement with ourexperimental observations, which suggest higheradsorption capacity of the IIT carbon is related toits unique pore structure (mesoporosity) andavailability of the pores with average diameters ofabout 50 A� (Sorbonorite 4 has an average poresize of 13 A� ).

Fig. 5. Adsorption isotherms constructed based on surface coverage model (� IIT Carbon, � Sorbonorite 4).


Fig. 6. The extent of phenol removal due to physical adsorp-tion and biodegradation/adsorption for (a) sorbonorite 4, and(b) IIT carbon.

from waste streams; bioactivation can enhance theextent of organic removal in the FB reactors, andpore structure has negligible impact on the bioac-tivity of the catalysts. The highest adsorptionefficiency was observed for IIT carbon at dilutesolutions.

4. Conclusion

The purpose of this study was to evaluate or-ganic removal capability of a novel mesoporousactivated carbon and biocatalyst produced frompapermill sludge. A commercially available acti-vated carbon, sorbonorite 4, was used as a refer-ence in this study.

The analysis of the activated carbon and bioac-tivated carbon produced at IIT suggest that IITcarbon has higher adsorption capacity and molec-ular surface coverage than sorbonorite 4, at phe-nol concentrations less than 10 mg/l. The fluidized

Fig. 7. Microscopic view of the IIT carbon (at the top), andsorbonorite 4 (at the bottom) with the biofilm shown in white(500× ).

the characteristics of their surface chemistry. Ourrecent laboratory tests have shown that themethod of production and selection of raw mate-rial can have a pronounced impact on the chem-istry of the produced carbons (work in progress).

The bioactivated carbon particles were also ex-amined microscopically upon completion of eachcolumn study. The optical micrographs obtainedfor these carbons are shown in Fig. 7. The pres-ence of biofilm on the surface of the activatedcarbon (the white layer) is evident in these micro-graphs. Also noticeable in Fig. 7 are the differ-ences in the surface characteristics of the twoBACs. The BACIIT contains larger pores as antic-ipated. The uniform removal efficiencies of thebioactive catalysts, however, suggest insufficientimpact of the pore structure on the extent ofcatalyst bioactivity.

These results indicate that activated carbonproduced from paper mill sludge at IIT can beused significantly to remove organic pollutants


bed reactor study, however, indicates comparablebut slightly lower phenol removal efficiency for theproduced carbon at IIT. While the removal effi-ciency of the carbons studied was 65–70%, theproduced bioactive catalysts were able to removeup to 97�1.2% of phenol in wastewater during thefirst few hours of operation.

To eliminate environmental pollution andlandfill usage due to uncontrolled disposal of sludgeproduced at paper mill facilities, sludge must bepretreated using very often high cost and laborintensive processes. The procedure developed forconversion of waste sludge to carbon-based catalysthere offers significant potential for reducing thiscost and the environmental damage resulting fromuncontrolled disposal of the waste sludge. Theusage of waste sludge is especially important dueto its mass production and resulting occupation ofvaluable landfill space.

The other significant feature of the processdeveloped in this study is the production of acost-effective and highly efficient activated carbonor carbon-based catalyst from waste material, whilemost activated carbons are produced from coal,coke, and other natural resources. This processcould facilitate wastewater treatment using carbonsproduced from industrial waste itself, and promoteconservation of the naturally available resourcescurrently used to make activated carbons needednot only for physical adsorption but also forbiodegradation of organic pollutants.

Acknowledgements

The authors would like to thank IIT ResearchInstitute for providing financial support for thisresearch. We would also like to thank Royal ThaiFellowship program for financial support providedfor one of the co-authors, Mr. W. Weangkaew.

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