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KMID : 1024520110200020185
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Journal of the Environmental Sciences
2011 Volume.20 No. 2 p.185 ~ p.197
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Attenuation of Chlorinated Pesticides(2,4-D, atrazine) Using Organoclays
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Choi Ji-Yeon
Shin Won-Sik
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Abstract
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Sorption of chlorinated pesticides such as 2,4-dichlorophenoxyacetic acid (2,4-D) and atrazine onto natural clays (montmorillonite and zeolite) modified with cationic surfactant, hexadecyltrimethyl-ammonium (HDTMA) and a natural soil was investigated using batch adsorbers. The clays were transformed from hydrophilic to hydrophobic by the cation exchange between clay surface and HDTMA up to 100% of the cation exchange capacity (CEC). Physicochemical characteristics of the sorbents such as pH, PZC (point of zero charge), organic carbon content (foc), fourier transform infrared spectroscopy (FT-IR), differential thermogravimetric analysis (DTGA) and X-ray diffraction (XRD) were analyzed. Sorption isotherm models such as Freundlich and Langmuir were fitted to the experimental data, resulting Langmuir model (R2 > 0.986) was fitted better than Freundlich model (R2 > 0.973). Sorption capacity (Q0) for 2,4-D and atrazine was in the order of HDTMA-montmorillonite > HDTMA-zeolite > natural soil corresponding to the increase in organic carbon content (foc). The sorption of the pesticides was also affected by pH. The sorption of 2,4-D decreased with the increase in pH, whereas that of atrazine was not changed. This indicated that the sorption capacity (Q0) of 2,4-D and atrazine was not affected by the solution pH because they exist as anionic (deprotonated) forms at pH above pKa. The results indicate that organoclay has a promising potential to reduce chlorinated pesticides in the effluent from golf courses.
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KEYWORD
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2, 4-D, Atrazine, Organoclay, Pesticide, Sorption
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