有机酸对镉在土壤矿物上吸附特征的影响

研究了有机酸对镉在土壤矿物上吸附特征的影响,结果表明:有机酸对镉在矿物上吸附的影响基本上是一致的:随着胡敏酸浓度的增加,镉的吸附量迅速增大;对低分子量有机酸(草酸、乙酸、柠檬酸等)而言,在浓度较低时,镉的吸附量随着有机酸浓度的增加而有所增大,但随着浓度的增加,镉的吸附量逐渐降低.存在胡敏酸时,高岭石、针铁矿和三羟基铝石对镉的吸附率随着pH的升高而迅速增大,而且吸附率一直高于其它条件下的吸附率,pH>5.0时,吸附率接近100%.在存在低分子量有机酸(草酸、乙酸、柠檬酸等)的情况下,在pH<5.5时,高岭石、针铁矿和三羟基铝石对镉的吸附率随着pH的升高有较大的差异,与矿物种类及有机酸类型有着密切的关系,之后随pH的升高而迅速增大.

Effects of organic acids on adsorption characteristics of Cadmium on soil minerals

Effects of organic acids on adsorption characteristics of Cadmium on s oil minerals were studied, the results showed: Effects of organic acids on the a dsorption of cadmium on the minerals were almost similar, i e amount of adsor be d cadmium increased with increasing the concentration of low molecular weight or ganic acid in solution at lower concentration, and decreased at higher concentra tion However, amount of adsorbed cadmium increased with increasing the concent r ation of humic acid in solution Adsorbed percent of cadmium on the minerals in c reased remarkably with increasing pH of the solution existing humic acid, and hi gher than adsorbed percent under other conditions Nearly 100% cadmium was adso rbed (pH>5 0 ), and there has larger difference in adsorbed amount of cadmium o n minerals with low molecular weight organic acids ligand (pH<5 5 ), which was r elated to the types of organic acids and minerals The adsorbed amount of cadmi um on minerals increased with increasing pH of the solution (pH>5 5)