pH值对锌离子污染高岭土压缩及离子扩散特性影响研究

摘要

To examine the effect of zinc ion on the compressive property of the saturated kaolin and the diffusion characteristics of zinc ion under different pH values,a series of one-dimensional consolidation tests and soil column diffusion tests were carried out with artificially prepared remolded soil samples.The test results indicate that the compressibility index of zinc-contaminated kaolin does not change much if the concentration of zinc ion is lower than 0.05 mol/L.However,the increase of precipitation of Zn (OH) 2 will lead to a slight decrease in soil compressibility.The decreasing velocity of the zinc ion in the free solution is the highest over the alkaline kaolin,then the neutral kaolin,and lowest over the acid kaolin.The electrical conductivity (EC) of the solution can indirectly reflect the concentration of dissolved zinc ion.When the kaolin is in neutral and alkaline environments,the EC of the free solution above the soil column is positively correlated with the concentration of zinc ion in the solution.But if the kaolin is in an acidic environment,the conductivity of the free solution above the soil column is negatively correlated with the concentration of zinc ion.Such an opposite variation under different pH value of soils should be paid more attention to.%为了研究不同酸碱环境下锌离子对饱和高岭土压缩特性影响,以及锌离子向其中扩散特性,利用室内人工配制的重塑土开展了一维固结试验和土柱扩散试验.试验结果表明,锌离子浓度不高于0.05 mol/L时,污染土的压缩指数变化不大,但氢氧化锌沉淀量的增加会导致高岭土的压缩性略有降低.高岭土处于碱性环境时,其上部自由溶液中锌离子浓度降低最快,中性环境次之,酸性环境时最慢.溶液电导率可间接反映出其中的溶解态锌离子浓度,高岭土处于中性和碱性环境时,土柱上部自由溶液的电导率与溶液中锌离子浓度呈正相关,而当高岭土处于酸性环境时,土柱上部自由溶液的电导率与溶液中锌离子浓度呈负相关,对于这种酸碱土体环境下的反常规律,在利用溶液电导率快速评价重金属离子浓度时需引起重视.