磷促进水铁矿胶体迁移及离子阻滞效应:实验与模型计算

Phosphorus-facilitated transport of ferrihydrite colloid and retardation effect of ion:Experiment and model calculations

研究了饱和砂柱中FHC与P及FHC与P/Na(Ca)的共迁移.结果表明,吸附在FHC上的P为其表面提供了负电荷,从而促进了石英砂柱中FHC的迁移.pH 6.0和8.0时,对FHC迁移的促进作用较为明显,而pH 4.0时,P对FHC迁移没有促进作用.较高浓度的P(10mg/L)对FHC迁移促进作用更强.Na离子(1和10mmol/L)和Ca离子(0.5mmol/L)可导致P-FHC的沉积.Na离子通过提供离子强度对P-FHC迁移起到阻滞作用,但这种阻滞作用相对较弱.而Ca离子不仅通过离子强度,还通过增加胶体体系中电荷分布的异质性,以及在高pH值下与P反应产生沉淀后再与FHC之间发生异质聚集,阻滞FHC的迁移,而且其阻滞作用相对较强.该研究可为进一步探究环境中阴离子促进胶体和纳米颗粒迁移提供参考和依据.

The cotransport of FHC with P and P/Na(Ca)in the saturated sand columns was investigated.The results showed that P adsorbed on the FHC provided a negative charge to the FHC,which enhanced the transport of FHC in the quartz sand columns.The enhanced effect mainly occurred at pH 6.0 and 8.0,while it was hardly discovered at pH 4.0.A high concentration of P(10mg/L)had a stronger ability to enhance the transport of FHC.Both Na^(+)(1 and 10mmol/L)and Ca^(2+)(0.5mmol/L)could promote the deposition of P-FHC.The retarded effect of Na^(+)on P-FHC transport was owing to ionic strength,and the retarded effect was relatively weak.However,Ca^(2+)retarded FHC transport in multiple ways,including ionic strength,increase in the heterogeneity of charge distribution in the colloidal system,and heteroaggregation between generated precipitate and FHC at high pH.Therefore,retarded effect of Ca on P-FHC transport was strong.The results provided support for further investigation of the environmental behavior of anion-facilitated transport of colloid and nanoparticle.