Cr(Ⅵ)对两种黏土矿物在单一及复合溶液中Cu(Ⅱ)吸附的影响  

Effect of Cr(Ⅵ) Anions on the Cu(Ⅱ) Adsorption Behavior of Two Kinds of Clay Minerals in Single and Binary Solution

作　　者：刘娟娟[1] 梁东丽[1] 吴小龙[1] 屈广周[1] 钱勋[1] 

机构地区：[1]西北农林科技大学资源环境学院,杨凌712100

出　　处：《环境科学》2014年第1期254-262,共9页Environmental Science

基　　金：国家自然科学基金项目(41171379);西北农林科技大学创新团队项目

摘　　要：采用批量吸附实验研究了高岭石和蒙脱石两种黏土矿物对Cu(Ⅱ)的吸附,利用各种吸附模型分析了两种黏土矿物对单一Cu(Ⅱ)溶液及Cu(Ⅱ)-Cr(Ⅵ)复合溶液中Cu(Ⅱ)的吸附机制,同时探讨了pH对两种黏土矿物Cu(Ⅱ)吸附的影响,旨在搞清土壤中重金属的环境化学行为并为土壤中重金属复合污染的修复提供依据.结果表明,高岭石和蒙脱石对单一及复合溶液中Cu(Ⅱ)的吸附是一个先快后慢的过程,120 min基本达到吸附平衡;二级动力学方程为描述两种黏土矿物Cu(Ⅱ)吸附的最佳动力学模型(R2>0.983),其次是内表面扩散模型和一级动力学模型.内表面扩散模型和Boyd模型拟合结果均说明发生在矿物边缘和表面的膜扩散作用是影响吸附的限速步骤.高岭石对Cu(Ⅱ)的吸附符合Freundlich方程(R2>0.971),说明高岭石表面有多种能量不一致的吸附位点,即为不均匀表面;而蒙脱石对Cu(Ⅱ)的吸附符合Langmuir方程(R2>0.983),说明其为单层分子吸附,即化学吸附.两种黏土矿物对Cu(Ⅱ)的吸附均随pH的升高呈先升高后下降的趋势,在pH=5.0时达到最大吸附量;且以Q蒙脱石>Q高岭石,Q单一Cu>Q Cu-Cr复合.Cr(Ⅵ)存在会降低Cu(Ⅱ)的吸附,以pH=6.0时Cr(Ⅵ)对Cu(Ⅱ)的吸附影响最小.The adsorption of Cu（ II ） on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu（ II ） on the two clay minerals in single Cu（ II ） and Cu（ II ）- Cr（ VI ） binary solutions, and the impact of solution with various pH values on the adsorption of Cu（ II ） on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu（ II ） on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model （R2 〉 0. 983） showed the highest agreement with the adsorption of Cu（ II ） on the two mineral clays, followed by the intra-partiele diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with Iche Freundlich equation （R2 〉 0. 971 ）, which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite （R2 〉 0. 983） , which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu（ II ） on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5. 0, and was in the order of Q 〉 Qkao and Qsi,glecu 〉 Qco-crbi,ary- Cr（VI） in the solution reduced the adsorption of Cu（ 1I ） , and the minimal inf

关 键 词：高岭石 蒙脱石 吸附 复合污染 Cu(Ⅱ) PH 

分 类 号：X131.3[环境科学与工程—环境科学]