接枝微粒PMAA/SiO2在水介质中对杀虫剂抗蚜威的吸附机理

以硅胶表面接枝聚甲基丙烯酸(PMAA)的复合型功能微粒PMAA/SiO2为固体吸附剂, 对水介质中的抗蚜威进行了静态吸附实验, 通过考察温度、pH值及盐度(NaCl浓度)对吸附容量的影响, 重点研究了PMAA/SiO2对抗蚜威的吸附机理. 为确认所提出的机理的正确性, 还采用紫外光谱吸收法, 研究了单体甲基丙烯酸与抗蚜威之间的相互作用, 也考察了在非水介质CCl4中PMAA/SiO2对抗蚜威的吸附作用. 研究结果表明, PMAA/SiO2对抗蚜威具有强的吸附作用, 吸附的驱动力是氢键、静电以及疏水相互作用三种作用的协同, 其中主驱动力是静电相互作用. 温度升高, 吸附容量减小; 盐度增大, 吸附容量降低; 当pH<8时, 吸附容量随pH升高而增大; 当pH>8时, 吸附容量随pH升高而减小; 当pH=8 时,吸附容量最大.

Adsorption Mechanism of Grafting Particle PMAA/SiO2 for Pirimicarb in Water Medium

The functional composite-type particle PMAA/SiO2,which was prepared by grafting polymethacrylic acid(PMAA)onto the surface of silica gel particles(SiO2),was used as solid adsorbent,and the static adsorption experiments for pirimicarb in water were performed.The adsorption mechanism of PMAA/SiO2 for pirimicarb in water was mainly studied via examining the effects of various factors,such as pH value,concentration of sodium chloride(NaCl)and temperature on the adsorption capacity.In order to confirm further the adsorption mechanism put forward,the interaction between the monomer methacrylic acid and pirimicarb was investigated by using UV spectral absorption method.The adsorption behaviour of PMAA/SiO2 for pirimicarb in carbon tetrachloride(CCl4)was also studied.The experimental results showed that the functional composite-type particle PMAA/SiO2 had strong adsorption ability for pirimicarb.The driving force of the adsorption was the synergism of electrostatic,hydrogen bond and hydrophobic interactions.Among them,the electrostatic interaction was the main driving force.The adsorption capacity decreases with the enhancement of temperature;as salinity of the solution increases,the adsorption capacity decreases;when pH<8,the adsorption capacity increases with the increase of pH value,decreases with the increase of pH value as pH>8,and when pH=8,the adsorption capacity has a maximum.