有机膨润土对水溶液中甲基对硫磷的吸附特性研究

采用室内增溶性实验及吸附实验,研究了表面活性剂十六烷基三甲基溴化胺(CTMAB)对甲基对硫磷的增溶作用,并进一步研究了甲基对硫磷在硼润土-十六烷基三甲基溴化胺体系中的分配特性。结果表明,CTMAB对膨润土吸附甲基对硫磷有明显的增溶作用,且当CTMAB其浓度大于CMC时,增溶效果显著;在低浓度表面活性剂条件下,膨润土对甲基对硫磷的吸附量随着CTMAB浓度的增加而增加,吸附在膨润土表面的CTMAB并不是作为一个分配体而存在,而是作为一个有效的吸附薄膜;在高浓度表面活性剂条件下,膨润土对甲基对硫磷的吸附量随着表面活性剂浓度的增加而降低。

Adsorption of Methyl Parathion to Bentonite with Surfactant in Water

To provide novel insight to interactions of organic pesticide with the mineral-adsorbed surfactant,the experiments of solubility enhancement of organic pesticide (methyl parathion) by cationic surfactant cetyltrimethylarnmonium bromide (CTMAB) in water were carried out,and the sorption of methyl parathion to bentonite with CTMAB were also investigated. The results showed that different concentrations of CTMAB increased remarkably the solubility of methyl parathion,when the concentration of CTMAB was above the CMC,the enhancement was more obvious. The adsorbed amounts of parathion-methyl by bentonites increased with increasing CTMAB concentration until they reached a maximum and then decreased significantly. Methyl parathion sorption coefficients with mineral-adsorbed CTMAB,Kss,greatly depended on the surfactant loading in the solid. At low CTMAB levels,the Kss values increased with increasing adsorbed surfactant mass,reached a maximum,and then decreased with increasing surfactant loading. At low adsorbed-surfactant levels,the resulting mineral adsorbed surfactant via the cation-exchange appeared to form a thin organic film which effectively adsorbed the methyl parathion,resulting in very high Kss values; at high surfactant levels,the sorbed surfactant on minerals appeared to form a bulk-like medium that behaved essentially as a partition phase rather than an adsorptive surface,with the result of Kss significantly decreasing that less depended on the CTMAB loading.