离子强度和磷酸盐对铁铝矿物及土壤吸附As（V）的影响

选用针铁矿、赤铁矿、水铁矿、水铝矿4种铁铝矿物以及性质差异较大的黑土、紫色土和红壤3种土壤,研究离子强度和磷酸盐对其吸附As(V)的影响。结果表明,在0.01、0.1、1mol.L-13种离子强度下,矿物和土壤对As(V)的吸附量无明显差异或随离子强度增大而增大,其对砷的吸附以专性吸附为主。磷酸盐对矿物和土壤吸附砷的影响与其添加顺序及摩尔浓度比有关。水铝矿和水铁矿在这3种添加顺序下的砷吸附量无明显差异,仅在P/As摩尔比较大时表现出下降趋势;而在针铁矿和赤铁矿两种矿物上,先添加砷时的砷吸附量高于先添加磷时或两者同时添加时,且砷吸附量随P/As摩尔比的增加而逐渐下降。在黑土、紫色土和红壤上,先添加砷比先添加磷或两者同时添加时的砷吸附量均要高,尤其是在紫色土上。随P/As摩尔比升高,土壤对砷的吸附量表现出下降趋势。

The Effect of Ionic Strength and Phosphate on As(V) Adsorption on Different Iron/Aluminum Minerals and Soils

Four iron/aluminum minerals and three soils were chosen to study the effect of ionic strength and phosphate on As(V) adsorption.The results showed that,As(V) adsorption quantities by minerals and soils showed no significant differences or increased with the increase of ionic strength at the ionic strength of 0.01 mol·L-1,0.1 mol·L-1 and 1 mol·L-1 respectively,suggesting As(V) specific adsorption.The effect of phosphate on As(V) adsorption by minerals and soils depended on P/As molar ratio and addition sequence.There was no significant differences of As(V) adsorption among three addition sequences on gibbsite and ferrihydrite,and As(V) adsorption decreased significantly when P/As molar ratio was higher.On goethite and hematite,As(V) adsorption were higher when arsenate was added first than that when phosphate was added first or phosphate and arsenate were added at the same time,and As(V) adsorption decreased gradually with the increase of P/As molar ratio.As(V) adsorption quantities of black soil,purple soil and red soil were the highest when arsenate was added first,especially in purple soil.With the increase of P/As molar ratio,As(V) adsorption decreased gradually on three soils.