| 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 |
| 摘要点击 2438 全文点击 1075 投稿时间：2013-04-19 修订日期：2013-06-19 |
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| 中文关键词 高岭石 蒙脱石 吸附 复合污染 Cu(Ⅱ) pH |
| 英文关键词 kaolinite montmorillonite adsorption combined pollution Cu(Ⅱ) pH |
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| 中文摘要 |
| 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 >QCu-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. |
| 英文摘要 |
| 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-particle 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 the 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 Qmon. >Qkao. and QSingle-Cu >QCu-Cr binary. Cr(Ⅵ) in the solution reduced the adsorption of Cu(Ⅱ), and the minimal influence of Cr(Ⅵ) on Cu(Ⅱ) adsorption was observed at pH=6.0. |
