CTMAB-膨润土对水溶液中4种农药的吸附特性
The Adsorption of Four Pesticides in Wastewater by Cetyltrimethylammonium Bromide (CTMAB)Modified Bentonites
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摘要: 用溴化十六烷基三甲铵(CTMAB) 制得改性膨润土, 研究了CTMAB-膨润土吸附水中甲萘威、甲基对硫磷、克百威、多菌灵的性能和适宜条件。结果表明: CTMAB-膨润土对水溶液中4 种农药有较强的吸附能力, 且与CTMAB 在膨润土上的实际交换量有关, 随着表面活性剂浓度的增大而增大; 但CTMAB 浓度≥4% 时, 实际发生吸附的农药就不再随着加入量的增加而增大。4 种农药的吸附等温线呈线性, 表明分配模式是主要的吸附形式。有机膨润土对4 种农药的吸附很快, 大部分农药在10 m in 内被吸附。pH 值变化对吸附有不同的影响, 并与农药性质有关: 低pH 值会降低有机农药的吸附量, 4 种农药在pH4～ 10 时吸附量较稳定,高pH 值导致多菌灵的吸附量增加, 而甲萘威、甲基对硫磷和克百威有分解现象。Abstract: The modifying bentonites with Cetyltrimethylammonium Bromide(CTMAB) have been done and the properties and optical absorbed conditions for CTMAB-bentonites to adsorb carbaryl, parathion methyl, carbofuran,and carbendazim in wastewater have been investigated. The results indicate that the adsorptive capacity of CTMAB-bentonites is significant and revalent to the real exchange volumes of CTMAB in the bentonites.The more contents of CTMAB exist in the bentonites, the stronger adsorptive capacity they have. As CTMAB concentrations are beyond 4%, the adsorptive capacity of organic clays becames maximum and keeps unchangeable. Adsorption isotherms are linear, indicating that partition model may be predomindant. Adsorption of four pesticides is very rapid,with the bulk of the adsorption occuring within the first 10 mintues of contact. The pH variation has different effects on adsorption capacity, which depend on the characters of pesticides. The research has shown that low pH decreases the adsorption capacity of CTMAB-bentonites. While adsorption rate of these four pesticides is stable in the pH range of 4～10. High pH results in increase of carbendazim adsorption and alkali hydrolysis of carbaryl, parathion methyl, carbofuran
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