【摘要】 用一次平衡法研究了两种可变电荷土壤与As(Ⅲ)之间的吸附和氧化还原反应。结果表明,当As(Ⅲ)溶液平衡浓度由0·25上升到1·0mmolL-1,砖红壤对砷的吸附量由15·0增加至25·9mmolkg-1,红壤由7·6增至13·0mmolkg-1,砖红壤对砷的吸附量约为红壤的2倍,这是因为前者铁、铝氧化物的含量高于后者。在pH3~7范围内,土壤对As(Ⅲ)的吸附量随pH的增加而增加。砖红壤中的氧化锰能将As(Ⅲ)氧化为As(V),砷的氧化量在pH3~7范围内随体系pH的增加而减小。砷在红壤中的氧化反应不显著。用1·0molL-1的KNO3对吸附性砷进行解吸的结果表明,砷的解吸率在35%以下,说明大部分砷通过形成内圈型表面络合物为土壤所吸附。在pH2~7范围内,砷的解吸率随吸附体系pH的升高而增加,说明较高pH下外圈型表面络合物的比例增加。更多还原

【Abstract】 Adsorption and redox reactions between As（Ⅲ） and two variable charge soils collected from Guangdong province and Jiangxi province were studied with the batch method. As（Ⅲ） adsorption by the soils increased with the amount of As（Ⅲ） added. The latosol adsorbed more As（Ⅲ） than the red soil did, because the content of iron and aluminum oxides in the former was higher than that in the latter. As（Ⅲ） adsorption by both soils increased with pH. As（Ⅲ） could be oxidized to As（V） by manganese oxides in the latosol, while no appreciable redox reactions with As（Ⅲ） were observed in the red soil. As（Ⅲ） oxidization decreased with increasing pH. The results from desorption of As（Ⅲ） by 1.0 mol L -1 KNO₃ indicated that the desorption rate of adsorbed As（Ⅲ） was less than 35%, suggesting that most As（Ⅲ） was adsorbed through the formation of inner-sphere surface complexes on the soils. The desorpation rate of As（Ⅲ） increased with the pH of the adsorption system in the [JP2]experiment, indicating that the proportion of outer-sphere surface complexes to the total surface complexes increased at higher pH.更多还原