Liao Chiu-Jung, Chen Chou-Pin, Wang Ming-Kuang, Chiang Po-Neng, Pai Chuan-Wen
Department of Environmental Engineering and Science, National Pingtung Universityof Science and Technology, Neipu, Pingtung, Taiwan.
Environ Toxicol. 2006 Feb;21(1):71-9. doi: 10.1002/tox.20158.
The organoclays Wyoming montmorillonite (SWy-1, Mon), W. R. Grace vermiculite (Ver), and Tung-Wei (Tw) soil montmorillonite were prepared to sorb or remove chlorophenoxy propionic acids (CPA) pollutants such as 2,4-dichlorophenoxy acid (2,4-DP), 2,4,6-tri chlorophenoxy acid (2,4,6-TCP), and pentachlorophenoxy propionic acid (PCP). The objective of this study was to evaluate the behavior of organoclays that have sorbed three types of CPA and to assess the applicability to basaltic-developed iron-rich calcareous soil. This type of soil contains high amounts of montmorillonite. The mean-layer charge per formula unit of Mon, Ver, and Tw clays, characterized by the alkylammonium method, was 0.27, 0.70, and 0.52 mol(c)/O(10)(OH)(2), respectively. The sorption isotherms of 2,4-DP, 2,4,6-TCP, and PCP sorbed by hexadecyltrimethyl-ammonium (HDTMA organoclay, 150% cation-exchange capacity) were evaluated. The data on sorption of CPAs fit well with the Freundlich isotherm equation. In general, the sorption of three types of CPA by the organoclays showed a linear relationship, with a high correlation coefficient (r > 0.935). The K(f) value of PCP was the same as that of 2,4,6-TCP sorbed by the organoclays and was higher than that of 2,4-DP. However, the 1/n(f) values of the three CPAs sorbed by the organoclays did not show significant differences. In general, maximum CPA sorption occurred at a pH of approximately 3, but very significant differences were observed for the 2,4,6-TCP and PCP sorbed by the organoclays. However, there was no significant difference in pH for 2,4-DP sorption. This should be related to the solubility and pKa of each CPA. The experimental results showed that solubility of 2,4-DP, 2,4,6-TCP, and PCP is a function of pH, ionic strength, and temperature.
制备了有机黏土怀俄明蒙脱石（SWy - 1，蒙脱土）、W.R.格雷斯蛭石（蛭石）和东卫（Tw）土壤蒙脱石，用于吸附或去除氯苯氧基丙酸（CPA）污染物，如2,4 - 二氯苯氧基酸（2,4 - DP）、2,4,6 - 三氯苯氧基酸（2,4,6 - TCP）和五氯苯氧基丙酸（PCP）。本研究的目的是评估吸附了三种类型CPA的有机黏土的行为，并评估其在玄武岩发育的富铁钙质土壤中的适用性。这类土壤含有大量蒙脱石。通过烷基铵法表征的蒙脱土、蛭石和Tw黏土每分子式单元的平均层电荷分别为0.27、0.70和0.52 mol(c)/O(10)(OH)(2)。评估了十六烷基三甲基铵（HDTMA有机黏土，150%阳离子交换容量）吸附的2,4 - DP、2,4,6 - TCP和PCP的吸附等温线。CPA的吸附数据与弗伦德利希等温线方程拟合良好。一般来说，有机黏土对三种类型CPA的吸附呈现线性关系，相关系数较高（r > 0.935）。PCP的K(f)值与有机黏土吸附的2,4,6 - TCP的K(f)值相同，且高于2,4 - DP的K(f)值。然而，有机黏土吸附的三种CPA的1/n(f)值没有显著差异。一般来说，CPA的最大吸附发生在pH约为3时，但有机黏土吸附的2,4,6 - TCP和PCP观察到非常显著的差异。然而，2,4 - DP吸附的pH没有显著差异。这应该与每种CPA的溶解度和pKa有关。实验结果表明，2,4 - DP、2,4,6 - TCP和PCP的溶解度是pH、离子强度和温度的函数。
