钠基膨润土对废水中Ni^(2+),Cu^(2+)的吸附效果

Adsorption Performance of Sodium-Based Bentonite for Ni2+ and Cu2+ in Wastewater

为了提高膨润土吸附废水中Ni2+,Cu2+的效果,对其改性制备了钠基膨润土,考察了吸附时间、废水pH值以及Ni2+和Cu2+初始浓度对自制钠基膨润土吸附Ni2+,Cu2+效果的影响,分析了吸附等温线,并探讨了吸附机理。结果表明:钠基膨润土对Ni2+,Cu2+都有较好的吸附性能;初始阶段(前10 min)吸附很快,之后随时间延长吸附量提高甚微;pH值为6.2时,处理后的水质即可达国家排放标准;随着Ni2+,Cu2+初始浓度增加,去除率先增加后降低,而吸附量迅速增加,Ni2+和Cu2+初始浓度分别为25 mg/L和40 mg/L时,钠基膨润土对Ni2+,Cu2+的去除率均可达98.6%;钠基膨润土对Ni2+,Cu2+的吸附等温线符合Freundlich吸附等温式。

Na-based bentonite was prepared by modification of bentonite so as to improve the adsorption performance for Ni2+ and Cu2+ in wastewater.The effects of time,pH value of wastewater,and the initial concentration of Ni2+ and Cu2+ on the adsorption performance of Na-based bentonite were investigated.Besides,the adsorption isotherms were analyzed,and the adsorption mechanism was discussed.It was found that Na-based bentonite had good adsorption performance for Ni2+ and Cu2+.The adsorption rate at the early stage(within 10 min) was very fast,and then the adsorbed amount varied very slightly with extending adsorption time.Besides,after wastewater with a pH value of 6.2 was treated with Na-based bentonite,it was qualified in terms of relevant national discharge standard.Besides,the removal rate of Ni2+ and Cu2+ initially rose but declined later with the increase of their initial concentrations,and the adsorption capacity of Na-based bentonite significantly rose therewith.Namely,when the initial concentrations of Ni2+ and Cu2+ were 25 mg/L and 40 mg/L,their removal rates were as much as 98.6%.Moreover,the adsorption of Ni2+ and Cu2+ by Na-based bentonite could be well described by Freundlich adsorption isotherm.