电解质浓度对土壤吸附铜离子时氢离子释放的影响

EFFECT OF ELECTROLYTE CONCENTRATION ON RELEASE OF HYDROGEN IONS FROM SOILS ADSORBING COPPER IONS

研究了不同铜离子浓度、不同电解质浓度情况下,吸附铜离子时氢离子释放对两种可变电荷土壤和4种恒电荷土壤悬液pH的影响。研究结果表明,除了黄棕壤外,含铁量越高,由于吸附铜离子后所引起的土壤ΔpH最大值越小。加入的铜离子浓度为10-4 mol L-1时,铜离子吸附对中和曲线形状没有根本影响。在较低浓度时,铜离子吸附时氢离子的释放较少;而在较高浓度时,当体系pH大于一临界值时,开始释放大量氢离子。氧化铁是引起恒电荷土壤和可变电荷土壤在吸附铜离子时氢离子释放差异产生的主要原因。电解质浓度的变化对恒电荷土壤和可变电荷土壤吸附铜离子后中和曲线变化影响有很大的区别,含铁量越高,电解质浓度对土壤吸附铜离子后的氢离子释放的影响越小。

Effect of H＋ release from four constant charge soils and two variable charge soils on pH of their soil suspensions different in Cu ion concentration and in concentration of electrolyte was studied.Results indicate that for all the six samples,except for yellow brown soil,the higher their Fe content the lower the ΔpHmax caused by adsorption of copper ions.The adsorption of copper ions showed no significant effect on neutralization curves.When the copper ion was low in concentration,H＋ release was low,but when the copper ion was high in concentration and the pH value of the system exceeded a certain threshold,a large volume of H＋ was release.The presence of iron oxide was found to be the main cause for difference in H＋ release between constant charge soils and variable charge soils.The effect of electrolyte concentration on the neutralization curves of constant charge soils and variable charge soils after adsorption of Cu ions varied greatly.The higher the iron oxide content,the lower the effect of electrolyte concentration on post-Cu-ion-adsorption H＋ release.