Treating Disperse Dye Wastewater with organic clay

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1 Advanced Materials Research Submitted: ISSN: , Vol. 977, pp Accepted: doi: / Online: Trans Tech Publications, Switzerland Treating Disperse Dye Wastewater with organic clay Lixuan Wang a Yankun Cheng b PengHuo c Yanan Gao d Hebei Chemical & Pharmaceutical Vocational Technology college,, Shijiazhuang,China a @qq.com, b cyk0311@126.com, c @qq.com d @qq.com Key words: organic clay adsorption dye wastewater Abstract: The adsorption of disperse dye wastewater with organic clay by static tests is studied, Meanwhile, the composition of wastewater is analyzed by means of FT-IR,and organic clay is analyzed by means of XRD. The effect of ph, dosing quantity and concentration of wastewater on the efficiency of adsorption has been studied, and the relationship between the equilibrium concentration and adsorption capacity is concluded. In the end, the adsorption mechanism is preliminary discussed. Introduction Disperse dye wastewater is one of the refractory industrial organic wastewater, which contains a large number of dyestuff intermediates and unrecovered dye. 2% products drain away with the wastewater, producing every 1t dye [1]. The organic pollutants in disperse dye wastewater are mainly benzene, naphthalene series, azo, anthraquinone, halide, nitrocellulose, aniline and phenol substances, which lead to the large concentration, high colority and strong toxicity of wastewater. Biological method has been used in treating dye wastewater for many years [2]. It s difficult to treat dye wastewater by conventional approach, so there isn t economic and effective treatment technology of dye. Clay is a kind of widely distributed and cheap natural mineral [3]. It is silicate mineral which is composed of silicon tetrahedron and alumina octahedron with layered structure and strong adsorption. Organic clay is a new type of environmental friendly material, which is funded by researching the special properties of the clay layer. After modifying by quaternary ammonium salt cationic surfactants, clay can be more hydrophobic [4], so it can greatly enhance the affinity for organics in wastewater; meanwhile the spacing of clay layer is increasing, in that it can enhance the adsorption of pollutants. Its adsorption capacity can improve times [5-7]. Lee Shu and his group [8] researched the adsorption behavior of PAM on natural na-bentonite, showing that bentonite is a kind of high cost-effective wastewater treatment material. Zhu Lizhong and his group [9-11], Li Na and her group [12] researched the adsorption conditions and mechanism of aniline, phenol, nitrophenol, phenanthrene and so on by organic clay, which is the theoretical basis for treating dye wastewater with organic clay. The paper studies the adsorption behaviors of organic clay on disperse dye wastewater. 1 Material and Methods 1.1Experimental Material Organic clay: Organic clay, modifying by hexadecyl trimethyl ammonium bromide (HDTMA), bought from a company in Zhe Jiang, with white appearance, the size of dry powder %. Selected samples: The wastewater, taken from a dye factory s regulating-pool in Zhe Jiang after coagulation pretreatment, the quality of the experimental water is shown in Table 1. 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 Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-12/05/16,20:01:36)

2 280 Material Science, Engineering Research, Management and Information Technologies Table 1 The Quality of the Experimental Water CODCr(mg/L) colority(times) ph Adsorption Test Suspend 0.5 g, 1.5 g, 2.5 g and 5.0 g organic clay in four flasks of 100ml. Distribute 50ml experimental water into flasks with organic clay and shake up. Put the flasks into water oscillator with constant temperature and oscillation intensity of 150 r/min.stand for 12h after 20 min s oscillation. Test CODCr of clear liquid after centrifugal separation for 10min in speed of 3600 r/min. 1.3Analysis Method In order to verify whether the disperse dye wastewater of organic pollutants permeate into the lamellar of organic clay or not, analyze the organic clay by means of XRD before and after the adsorption. Analyze the functional groups that may contain pollutants in wastewater through the FT-IR (Fourier transform infrared spectroscopy). XRD is analyzed by RIGAKU D/Max-rA X-ray diffraction analyzer; FT-IR is analyzed by VECTOR22 fourier transform infrared spectrometer of BRUKER, and squash method of potassium bromide is used in testing the selected samples. Evaporate a certain quality of wastewater into constant weight in thermostatic water bath and detect the residue by FT-IR. Bake the organic clay after centrifugal separation in dryer for 6h, and then grind it for XRD detection. 2Result and Discussion 2.1Adsorption Isotherm Suspend 0.5g, 1.5 g, 2.5g and 5.0g organic clay, 50ml wastewater, do not adjust the PH of wastewater. Oscillate 20min in thermostatic water bath. The result of adsorption experiment is shown in Figure 1. The absorptive capacity is highest with 0.5g organic clay, which is mg/g. The adsorption isotherm is upward. Adsorption is a kind of physical and chemical process, what molecule is constrained by organic clay. The amount of hydrophobic organic compounds, which adsorbing from water, is closely water is high enough to its solubility, adsorption 400 isotherm of organic pollutants (pops) in 350 particulate matter is a straight line. There are 300 aliphatic compounds and aromatic compounds 250 / ( m g / g ) q 200 in disperse dye wastewater. Organic clay 量附 150 absorbs aliphatic compounds by 吸 100 distributional effects. The organic phase in 50 organic clay isn t pure alkyl organic phase, 0 which is a mixture of alkyl and aliphatic 平衡浓度 C/(g/L) compounds, so the adsorption is improved. It Equilibrium concentration makes the adsorption isotherm upward. Fig.1 Adsorption Isotherm Adsortption q/()mg/g 2.2The Influence of PH on Removal Rate of CODCr Suspend 0.5 g and 1.5g, 2.5g and 5.0g adsorbent in erlenmeyer flasks. Regulate them by concentrated sulfuric acid or 5 mol/l NaOH solution. Pour 50ml wastewater into each erlenmeyer flask and mix them completely. Stand for 12h at room temperature after 20 min s oscillation. Then test and analyze the sample after centrifugal separation.

3 Advanced Materials Research Vol Figure 2 shows that the removal rate of CODCr changes with the change of PH. The removal rate of CODCr is higher in acidic or alkaline wastewater, while it is lower in neutral wastewater. The removal rate of organic pollutants in wastewater is related to its state in the wastewater. The raw materials of disperse dye are usually -NO2, NH2, -COOH and other functional groups, whose amino acid is typical alkaline group and -COOH is a typical acidic group. Matter with -NH2 has the character of alkali, while matter with -COOH has the characteristics of acid. The concentration of H + or OH - in the wastewater changes with the change of PH. The ionization of organic pollutants in the wastewater is restrained, so the water s solubility decreases and pollutants hydrophobicity increases. It s convenient for the organic pollutants dissolving into organic clay, so the removal rate of CODCr in acidic and alkaline wastewater is higher than that in other conditions. Fig.2 The Influence of PH on Removal Rate of CODCr 2.3 The Influence of Dosage on the Removal Rate of CODCr Figure 3 shows the relation between dosage and adsorption quantity of organic clay. Measure 50ml wastewater at room temperature, and then change the amount of organic clay with the original amount and the initial concentration of wastewater. In that way we can study the relation between amount and adsorption quantity of organic clay. Adsorption capacity gradually reduced as the amount of organic clay increasing. The absorptive capacity is highest with 0.5g organic clay, while it s lower with 5.0g organic clay. Considering the removal rate of CODCr, it s advisable to use 1.5g organic clay in the test. Fig.3 The Influence of Dosage on the Removal Rate of CODCr

4 282 Material Science, Engineering Research, Management and Information Technologies 2.4 The Influence of Wastewater Concentration on the Removal Rate of CODCr Figure 4 shows the relation between wastewater concentration and CODCr s effect of removal. Suspend 1.5g organic clay in several conical flasks and then mix 50mL wastewater of different concentrations into the flasks without adjusting wastewater ph. The results show that the removal rate of CODCr increased with the decreasing concentration of wastewater. The removal rate of CODCr is slow, when CODCr concentration of wastewater is below 2800mg/L. It s not advisable that CODCr concentration of wastewater is below 2800mg/L when absorbing disperse dye wastewater with organic clay. Fig.4 The Influence of Wastewater Concentration on the Removal Rate of CODCr 2.5 FT-IR Analysis Figure 5 is the infrared spectrometer of disperse dye wastewater. The absorption peak is sharp near 3405cm -1 of functional groups vibration absorption, which is the effect of hydroxyl s vibration absorption. Absorption peaks near 1559cm -1 and 1466cm -1 are sharp and large, which are caused by the deformation vibration of benzene skeleton. The absorption peak near the 1559cm -1 is the effect of C=C-C=C antisymmetric contraction. The vibration absorption peak of -CH3 appears at 1347cm -1 and 1466cm -1. The absorption peak near cm -1 is the result of C-O stretching vibration. Different alcohols have different stretching vibration frequency. The vibration frequency of primary alcohol, secondary alcohol and tertiary alcohol decreases. Primary alcohol is at 1143cm -1, while secondary alcohol is at 1054cm -1 and tertiary alcohol is at 1118cm -1. Bending vibration of CH-(CH3)2 is near 1118cm -1.

5 Advanced Materials Research Vol Fig.5 FT-IR of Disperse Dye Wastewater 2.6 XRD of Organic Clay Analysis Figure 6 shows that the spacing of layers of organic clay changes before and after adsorbing disperse dye wastewater. Before the adsorption spacing of layers of organic clay is nm, while after adsorption it is nm. It is the results that organic pollutants enter into the layer of organic clay. Fig.6 XRD spectrum of Organic Clay Before And After Absorption Organic matter in disperse dye wastewater mainly consists of two parts, one part is disperse dye such as disperse blue, disperse orange, disperse red, disperse yellow and so on, the other part is intermediates that produced during the production process of dye. These organic molecules are small, whose structure do not contain water-soluble groups, but contain highly alkaline groups. Disperse dye can t dissolve in the water well, which is generally slightly soluble in water. Disperse dye can be evenly dispersed in water because of its fineness (1µm), and with the help of dispersant. Organic pollutant can dissolve in organic phase of granulated organoclay, in which way the interlayer spacing increases.

6 284 Material Science, Engineering Research, Management and Information Technologies 3 Conclusions (1)The adsorption isotherm is upward. The absorptive capacity is highest with 0.5g organic clay, which is mg/g. (2)The removal rate of CODCr changes with the change of PH in the condition of same dosage of adsorbent and wastewater. The removal rate of CODCr is higher in acidic or alkaline wastewater, while it is lower in neutral wastewater. The removal rate of CODCr increases with the decreasing concentration of wastewater. It proves that organic clay s absorption of organic pollutant in low strength wastewater is stronger. At the same time, it s not advisable that CODCr concentration of wastewater is below 2800mg/L. (3)The interlayer spacing of adsorbent increases after organic clay absorbing wastewater. It proves that organic pollutant in wastewater permeates into organic clay. References [1] Xu WeiChang. The Current Situation and Prospect of Wastewater-treatment in Dyestuff Industry. Dyestuff Industry, Vol.39-6 (2002),p.35 [2] LiYin,XiDanli. Analyses of dye and related compounds during biodegradation. Chinese Journal ofenvironmentalengineering, Vol.1-8 (2007),p.57 [3] Shao Qing, Yang Xinyu. Research on the application of modified clay to the treatment of wastewater from dyestuff technology.industrial Water Treatment, Vol (2006),P.84 [4] Wu Jiaqiang Ma Hongrui Wei Junfui,etl. Study on Modification andadsorption of Natural Montmorillonite and Graphite. Non-Metallic Mines, Vol (2008).P.61 [5] Boyd S A,Lee Jiunn-Fwu,Mortland M M.Attenuating organic contaminant mobility by soil modification.nature, Vol (1988),P.345 [6] Jaynes W F, Boyd S A.Clay mineral type and organic compound sorption by hexadecyltrimethylammonium-exchanged clays.soil Sci Soc Am J,Vol.55(1991),P.43 [7] Boyd S A,Mortland M M,Chou C T.Sorption characteristics of organic compounds on hexadecyltrimethylammonium-smectite.soil Sci Soc Am J, Vol. 42(1988),P.652 [8] LiShu,SunYabing,Feng,Jingwei,etl. Chinese Journal of Environmental Engineering,Vol.1-7 (2007),P.47 [9] Zhu Lizhong,Chen Baoliang,Luo Yu.The properties and mechanisms for organobentonites to sorb polycyclic aromatic hydrocarbons in water.acta Scientian Circumstantian,Vol.20-1 (2000),p21 [10] hu Lizhong,Wang Qing,Chen Baoliang.Sorption of Aniline and Phenol to Anion-cation Organobentonites from Water.Environmental Science,Vol.21-4 (2000),p.42 [11] Zhu Lizhong, Chen Baoliang,Ge Yuanshu,etl.Sorption Properties of p-nitrophenol to anion-cation organobentonitea from water.environmental Chemistry, Vol. 19-5(2000),p.419 [12] Liu Na,Chen Changshu,Fu Yunna. Adsorption of phenanthrene on organic clays. Environmental Pollution and Control, Vol (2006),p.811

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