Embed Size (px)
Citation preview
The Application of Epichlorohydrin-dimethylamine Polymer Flocculant
for Tannery Wastewater Treatment
Yan Niu1,a, Zhiwen Ding2,b,Baozhen Chen1,c,Yongfang Chen2,d
1Tianjin University of Science and Technology, Tianjin 300457, China
2China Leather and Footwear Industry Research Institute, Beijing 100016, China
[email protected], [email protected], c [email protected],
Keywords: epichlorohydrin-dimethylamine polymer; flocculation; tannery process waetewater,
Abstract: A cationic organic flocculant epichlorohydrin-dimethylamine(EPI-DMA) was employed
for the treatment of simulated leather-making process wastewater. The study aims at investigating
the flocculation performance of EPI-DMA for the leather dyeing wastewater which contains
fat-liquoring agent wastewater and retanning agent wastewater. The results show that decoloration
efficiency of EPI-DMA for dyeing wastewater can reach around 90% with proper dosage. For
containing retanning agent wastewater, EPI-DMA also has good flocculation performance, but for
containing fat-liquoring agent wastewater, flocculation performance of EPI-DMA was poor.
Introduction
Recently, with rapid development of industry technology, leather industry has become one of the
pillar industries in light industry in China. The amount of earning foreign exchange through export
of leather industry ranks national forefront among light industry exporting [1-3]
. But tannery
wastewater has become one of the most serious pollution sources with development of leather
industry. Animal skins and various chemicals are used as raw material in leather-making process,
and then the finished leather will be obtained. Many processes discharge wastewater, especially
dyeing and fat-liquoring wastewater. It contains not only dissolved organic matter but also retanning
agent, dye and fat which are not be absorbed, so higher value of COD and chroma are its water
quality characteristics. Water body is very turbidity from appearance.
In leather-making process, a large number of anionic chemical products are used [4]
, like dyes,
retanning agent, fat-liquoring agent. Flocculation method is one of the most popular treatment
processes to remove the dye, retanning agent and fat-liquoring
[5]. Inorganic flocculant has
limitations in removing some high-soluble and low molecular dyes [6]
. Organic polymeric flocculant
has drawn increasing attention in various industries. The research and application of novel
polymeric flocculant has been particularly active for the removal of dissolved and colloidal solids [7]
.
In this paper, a new type of organic cationic flocculant EPI-DMA was prepared and the possibility
of EPI-DMA used for tannery wastewater through simulated leather process wastewater was
studied.
Materials and methods
Main materials and equipments.Dyes: SELLAFAST BLACK BR was made in THL company.
ALIZARINE BROWN P-33-D and LEATHER RED S were made in Hoechst company. SG
retanning agent is provided by Beijing Zhongpi Tianyuan Science and Technology Co., Ltd. Acrylic
resin reanning agent is provided by Zhenjiang Wanli Leather Chemical Co., Ltd (Jiangsu China).
Advanced Materials Research Vols. 610-613 (2013) pp 480-484Online available since 2012/Dec/13 at www.scientific.net© (2013) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.610-613.480
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 130.15.241.167, Queen's University, Kingston, Canada-09/08/13,02:44:37)
JR-309 retanning agent is provided by Zhejiang Shenghui Chemical Co., Ltd. All those kinds of
dyes and retanning agents are industrial products. All dyes and retanning agent used in the
experiment are anionic type.
Epichlorohydrin;33% aqueous dimethylamine; Tetraethylenepentamine; All those regants were
purchased from Sinopharm Chemical Reagent Co., Ltd. All reagents used in the study were in the
analytical reagent grade. Electric-heated thermostatic water bath（Beijing Changan Science
Instrument Factory).TC-1810 UV-VIS spectrophotometer（Beijing Purkinje General Instrument Co.,
Ltd., China ）
Preparation of EPI-DMA .Reaction principle: Epichlorohydrin molecule containing an epoxy
bond and a C - Cl bond has strong reactivity, so it is a bifunctional compounds. For this reason,
Epichlorohydrin -dimethylamine polymer synthesized from epichlorohydrin and dimethylamine
polymerization with tetraethylenepentamine as crosslinking agent under oxidation-reduction system.
Method: A 250ml round-bottomed, dried and four-necked separable flask with a mechanical stirrer,
thermometer with a temperature controller equipment was charged with epichlorohydrin and
dimethylamine in accordance with molar ratio of 1.5:1. Then a small amount of
tetraethylenepentamine as crosslinking agent was added. Last, the quantitative initiator K2S2O8 and
Na2SO3 were added. The temperature was heated to 65℃ and this temperature was kept about 5
hours.
Structural formula of EPI-DMA as Fig.1
Fig.1 Structural formula of EPI-DMA
Flocculation experiment. Simulated leather dyeing wastewater was prepared by adding 0.1g
tested dye to 1L tap water. Then respectively prepare 1 g/L wastewater containing fat-liquoring
agent and 1 g/L wastewater containing retanning agent like that method. Flocculation experiments
were conducted with a jar test. After the addition of EPI-DMA flocculant, simulated wastewater was
mixed rapidly for 5 min at 150 rpm, followed by mixing slowly for 15 min at 50 rpm and settling
process for 40min .Then supernatant was determined.
Detection methods. Decoloration efficiency was determined with spectrophotometer at the λmax
of each dye. The color removal efficiency of flocculant was calculated by comparing the absorbance
difference between raw dyeing wastewater and supernatant sample. Chemical oxygen demand
(COD) was determined by dichromate standard method.
Results and discussion
About the parameters of EPI-DMA
The parameters of EPI-DMA are shown as table 1
Table.1 The parameters of EPI-DMA
Main component Appearance color Viscosity /(mPa﹒s) Cationic degree/(mmol/g)
Cationic quaternary
ammonium salt polymer
Light yellow
≥200
≥4.5
Advanced Materials Research Vols. 610-613 481
The impact of EPI-DMA dosage on decoloration efficiency for simulated leather dyeing
wastewater. The dosage of EPI-DMA is an important factor affecting the flocculation decoloration
process. We choose three kinds of dyes to respectively prepare simulative leather dyeing
wastewater.
Fig.1 The impact of dosage EPI-DMA on decoloration efficiency
As can be seen from Fig.1, decoloration rate of three kinds of dyes were increased with the
increasing of dosage of EPI-DMA. In the higher dosage, the decoloration efficiency of three kinds
of dyes reaches over 90%. In the experimental range, decoloration efficiency of SELLAFAST
BLACK BR and LEATHER RED S was improved greatly under dosage of 30～110mg/L
circumstances. When dosage of EPI-DMA is more than 110mg/L, decoloration efficiency of
SELLAFAST BLACK BR and LEATHER RED S is over 90%, and the highest can reach 96%. In
the same dosage, the decoloration efficiency of EPI-DMA for ALIZARINE BROWN P-33-D is less
than SELLAFAST BLACK BR and LEATHER RED S. The possible reason is that decoloration
efficiency of EPI-DMA is related with dye chemical structure and species. Decoloration efficiency
of EPT-DMA for three kinds of dyes is low with dosage of 30～90mg/L, because coagulation
particle is so small that can’t reach flocculation-subsidence requirement.
The impact of pH on the decoloration efficiency. It is significant that pH value can influence
on the flocculation decoloration efficiency. The main impact is that surface charge of colloid
particle can be changed, and consequently, it will affect the performance of flocculation decoloring.
In this experiment, we use 1% NaOH or 1% HCl to adjust the pH value of simulative leather dyeing
wastewater. The impact of pH on the EPI-DMA decoloration efficiency is shown in Fig.2
Fig.2 The impact of wastewater pH on decoloration efficiency
482 Progress in Environmental Science and Engineering
As can be seen from Fig.2, decoloration performance of EPI-DMA for three kinds of dyes used in
the experiment decrease gradually with pH value increase in the range of pH 3～9, and in this range
decoloration performance of EPI-DMA for three kinds of dyes is more than 75%. The decoloration
efficiency decrease obviously in the range of pH 9～11.This result is in accord with that cationic
flocculant is suitable for using in acidic environments .
Removal effect of EPI-DMA for simulated containing fat-liquoring agent wastewater .It
was found that removal efficiency of EPI-DMA for fat-liquoring was poor by exploratory
experiment. The possible reason for that is fat-liquoring agent contains emulsifier and other anionic
materials which can make fat-liquoring agent in the water more stable.
Removal effect of EPI-DMA for simulated containing retanning agent wastewater. It is
hard to determine directly the retanning agent content in the wastewater. So we determine
wastewater COD as retanning agent removal efficiency characterization method. We choose three
kinds of retanning agents as experimental material, and study the impact of dosage on the retanning
agents’ removal efficiency.
Fig.3 The impact of dosage of EPI-DMA on retanning agent wastewater COD removal rate
As can be seen from Fig.3, removal effect of EPI-DMA for retanning agent was significantly in
the dosage range of 0.5-0.7g/L. The decrease of COD can serves as evidence that EPI-DMA has
flocculation effect for retanning agent wastewater.
Conclusions
(1) EPI-DMA as a new type of cationic organic flocculant can effectively removed dyes which were
chosen in the study. Dyes’ chemical structure and species will influence on the decoloration rate.
(2) Decoloration rate of EPI-DMA for dyes was relatively high in the range of pH value 3～9.
EPI-DMA as cationic organic flocculant was suitable for acidic environments.
(3) For containing retanning agent wastewater, EPI-DMA also had obvious effect to decrease COD.
However, for containing fat-liquoring agent wastewater, the effect of COD decrease was poor
Acknowledgment
This work is supported by China Leather and Footwear Industry Research Institute under grant 863
major project (2011AA06A108) and national“twelfth five-year”plan for science & technology
support (2011BAC06B11).
Advanced Materials Research Vols. 610-613 483
Reference
[1] L. Ma, X.S.Zhang .Leather Science and Engineering.Vol.16 (2006), p.65-70.In Chinese
[2] T. Zhang, Z. Ren , Z. F. Liu . West Leather .Vol.33 (2011), p.28-32. In Chinese
[3] X. Y. Ma, L.Y. Lv, etc. China Leather. Vol.39(2010), p.25-29. In Chinese
[4] Y. J. Lan; Y. Chen . China Leather. Vol.31(2002), p.25-28. In Chinese
[5] Allegre. C; Maisseu. M; Charbit.F; etal. Hazard Mater. 2004.B116, p.57-64
[6] Joo. D. J; Shin. W. S, etc. Dyes Pigm. 2007 .73, p.59-64
[7] Ovenden C; Xiao, H. Colloids Surf. A Physicochem. 2002. Eng.Asp.197, p. 225–234.
484 Progress in Environmental Science and Engineering
Progress in Environmental Science and Engineering 10.4028/www.scientific.net/AMR.610-613 The Application of Epichlorohydrin-Dimethylamine Polymer Flocculant for Tannery Wastewater
Treatment 10.4028/www.scientific.net/AMR.610-613.480
