腐殖酸-高岭石胶体对铀(Ⅵ)在饱和多孔介质中迁移过程的影响

Effect of Humic Acid-Kaolinite on Uranium Transport in Saturated Porous Media

为探讨可溶性有机质存在条件下黏土矿物胶体对铀(Ⅵ)在饱和多孔介质中迁移的影响,选取2种石英砂(细砂和粗砂)分别构建均质构型的石英砂柱,研究了饱和水流条件下腐殖酸存在时高岭石胶体对铀在2种不同粒径石英砂中迁移的影响。结果表明,示踪溶质在2种均质石英砂柱中的穿透曲线相似且分布对称。当在石英砂柱中只通入铀(Ⅵ)溶液时,铀(Ⅵ)在2种粒径石英砂柱中的穿透量均较小(<25%),此时大量的铀(Ⅵ)通过络合作用吸附在石英砂表面上。当通入溶液中存在腐殖酸和高岭石胶体时,铀(Ⅵ)在2种石英砂柱中的穿透量增加,且在600～850μm石英砂中(58.36%)比250～425μm石英砂中(42.68%)穿透量更多。这充分表明腐殖酸—高岭石胶体和石英砂粒径是影响铀(Ⅵ)在地下环境中迁移的重要因素。

To investigate the effect of colloid on uranium(VI)transport in saturated porous media in the presence of soluble organic matter,two kinds of quartz sands(fine sand and coarse sand)were selected,and the column experiment with homogeneous configuration was constructed to study the effect of kaolinite colloid on the U(VI)migration in two quartz sands with different particle size in the presence of humic acid under saturated water flow.The results showed that the breakthrough curves of tracer in two homogeneous columns were similar and symmetric.When the U(VI)solution only was introduced into the column,the mobility of U(VI)in the two columns was small(<25%),and a large amount of U(VI)were adsorbed on the quartz sand through surface complexation.When humic acid and kaolinite colloids were present in the U(VI)solution,the transport amounts of U(VI)in both two columns were increased,and the transport amount(58.36%)in the quartz sand with600~850μm was more than that(42.68%)in the quartz sand with250~425μm.This demonstrated that humic acid-kaolinite colloids and sand size had large influence on uranium migration in subsurface environment.