摘要
比较了3种天然坡缕石粘土对不同程度磷污染水体的吸附净化能力,通过等温吸附实验和吸附动力学实验探讨了坡缕石粘土的磷吸附机制,并研究了不同形态铁负载对坡缕石粘土吸附净化磷污染水体性能和机制的影响。结果发现,3种天然坡缕石粘土对不同程度磷污染水体均有一定的吸附净化能力,其中含白云石较多的坡缕石粘土的磷吸附能力最强,吸附等温曲线呈S型,且Freundlich方程(R2=0.9776)比Langmuir方程(R2=0.9249)拟合效果更好;准一级方程、冥函数方程、抛物线扩散方程、准二级方程均能较好地模拟坡缕石粘土对磷的吸附动力学过程,说明坡缕石粘土对磷的吸附可能属于不均匀介质的多分子层吸附。此外,不同形态铁负载均能显著增强坡缕石粘土对不同程度磷污染水体的吸附净化能力,吸附等温曲线呈L型,Langmuir方程(Fe2+:R2=0.96,Fe3+:R2=0.9677)比Freundlich方程(Fe2+:R2=0.9657,Fe3+:R2=0.9361)能略好地拟合铁负载坡缕石粘土的磷吸附等温结果,说明铁负载坡缕石粘土的磷吸附过程可能是均匀介质的单分子吸附。适量白云石有助于提高坡缕石粘土的磷吸附净化性能,铁负载可能通过改变坡缕石的表面电荷和吸附活性位点来改变其磷吸附机制,从而提高其磷吸附性能。
Phosphate adsorption capabilities of different natural palygorskites and iron modified palygorskites in water with different phosphate concentrations were investigated, and the mechanisms of phosphate adsorption of natural and iron modified palygorskites were also studied through adsorption isotherms and adsorption kinetics experiments. The results show that the three palygorskite clays have different kinds of performance on removal of phosphate. For water quality of Grade V and lower than Grade V, the more dolomite they contain, the higher removal efficiency they have. The iron modification treatments increase the phosphate adsorption capabilities of natural palygorskite. The phosphate adsorption isotherm of natural palygorskite is an S-type isotherm, the Freundlich equation （R^2= 0. 977 6） provides better fitting than the Langmuir equation （R^2= 0. 924 9） in terms of R^2 values, suggesting that the adsorption of phosphate on palygorskite is inhomogeneous multilayer adsorption. On the basis of R^2 values, the kinetics of phosphate adsorption on the palygorskite can be satisfactorily described by the pseudo-first-order equation, power function equation, parabolic diffusion equation and pseudo-second-order kinetic equation. However, the phosphate adsorption isotherm of iron modified palygorskites is an L-type isotherm, the Langmuir equation （Fe^2＋：R^2= 0.96, Fe^3＋：R2= 0.967 7） provides better fitting than the Freundlich equation （Fe^2＋：R^2=0.965 7,Fe^3＋：R^2=0. 936 1） in terms of R^2 values, implying that the adsorption of phosphate on iron modified palygorskite is homogeneous monolayer adsorption. The results obtained reveal that, as the surface charges and adsorption activity sites of palygorskite are changed by iron modification, so do the phosphate adsorption mechanisms.
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
2008年第5期477-482,共6页
Acta Petrologica et Mineralogica
基金
江苏省科技厅科技攻关项目(BE2006371)
关键词
坡缕石粘土
磷
吸附净化
铁负载
palygorskite
phosphate
decontamination
iron modified
