K+、Na+、Ca2+共存离子对活性炭吸附Cr(Ⅵ)的影响

摘要

Simulated wastewater involving Cr (Ⅵ) and coexisting ions K+, Na+and Ca2+was studied, and activated carbon was used for adsorption treatment.The effect of coexisting ions on the adsorption of Cr (Ⅵ) by activated carbon was investigated.The results indicated that: (1) there was competition adsorption between coexisting ions and Cr (Ⅵ) , and the sequence of coexisting ions to adsorption of Cr (Ⅵ) was Ca2+>Na+>K+.The percentage of Cr (Ⅵ) removal by Ca2+was decreased by 44.16 percent point. (2) New infrared vibration peak appeared in 2 170cm-1 for Cr (Ⅵ) adsorbed activated carbon, which indicated that the adsorption of Cr (Ⅵ) by activated carbon was chemical process.For Cr (Ⅵ) and coexisting ions adsorbed activated carbon, no new infrared vibration peaks were observed.It was speculated that the adsorption of K+, Na+and Ca2+by activated carbon was physical process. (3) The adsorption of Cr (Ⅵ) by activated carbon was in conformity with Langmuir isothermal equation, and the adsorption kinetic accorded with pseudo-seccnd order equation.The adsorption of Cr (Ⅵ) by activated carbon was monolayer chemical adsorption.%以含有重金属离子Cr (Ⅵ) 以及共存轻金属离子K+、Na+、Ca2+的模拟废水为研究对象, 采用活性炭进行吸附处理, 探讨了3种共存轻金属离子对活性炭吸附Cr (Ⅵ) 的影响.结果表明: (1) 共存的K+、Na+、Ca2+与Cr (Ⅵ) 之间存在竞争吸附, 其影响活性炭吸附Cr (Ⅵ) 的大小顺序为Ca2+>Na+>K+, 其中Ca2+导致Cr (Ⅵ) 去除率下降44.16百分点. (2) 吸附Cr (Ⅵ) 的活性炭在2 170cm-1处出现新的红外振动峰, 表明Cr (Ⅵ) 与活性炭之间的吸附属于化学吸附.在同时吸附Cr (Ⅵ) 与共存离子的样品中, 未出现新的红外振动峰, 表明K+、Na+、Ca2+与活性炭间的吸附属于物理吸附. (3) 活性炭吸附Cr (Ⅵ) 的过程符合Langmuir模型, 属于单分子层化学吸附;其动力学曲线符合伪二级动力学模型.