黄河上游沉积物对磷酸盐的吸附动力学研究

Adsorption kinetics of phosphate onto sediments from the upper reaches of the Yellow River

研究了黄河上游10个不同表层沉积物在黄河水体中对磷酸盐（P）的吸附动力学及其影响因素和吸附机理。结果表明：不同黄河沉积物对P的吸附能力各不相同,但吸附量随时间的变化具有相同的趋势,吸附速率均在前8 h内较快,以后逐渐趋缓,在48 h时基本达到吸附平衡。不同黄河沉积物对P的吸附量均随P初始质量浓度的增加而增大,随沉积物质量浓度增大而减小,且也受水体pH值的影响,在pH为6.0~9.0范围内吸附量比较大。不同沉积物在不同P起始质量浓度下对P的吸附动力学均符合Lagergren二级吸附动力学模型及Weber–Morris扩散方程,求得二级吸附速率常数和扩散速率常数分别在10.85~229.29 g.mg-1.h-1和0.7×10-3~5.2×10-3 mg.g-1？h-1/2）之间,吸附过程由P在沉积物内的扩散控制。

The adsorption kinetics and its influencing factors,and adsorption mechanism of phosphate（P） onto 10 different sediments from the Upper reaches of the Yellow River were investigated.The results showed that the adsorption abilities of different sediments to P were different,but the change of P adsorption amount with time had the same trend.Adsorption rates were all faster within 0~8 h and then gradually getting slow within 8~48 h,and the adsorption tended to the dynamic equilibrium at 48 h.P adsorption amounts on different sediments increased with the increase of initial P concentration and decreased with the increase of sediment content,and P adsorption amounts were affected by pH value of waters and were bigger in the pH ranges of 6.0~9.0.At different initial P concentrations,P adsorption kinetics onto different sediments all followed second-order adsorption kinetic model and Weber-Morris diffusion equation which second-order adsorption rate constants and diffusion rate constants obtained by were in ranges of 10.85~229.29 g·mg-1·h-1 and 0.7×10-3 ~5.2×10-3 mg？g-1？h-1/2）,respectively.The adsorption equilibrium process of sediments to phosphorus was controlled by the intra-particle diffusion.