铜离子在钙基蒙脱石上的吸附解吸行为

吸附去除水溶液中重金属离子是废水处理研究最主要内容之一,而它的工业应用受限于吸附剂的解吸效率。利用动力学及Langmuir等温模型研究了铜离子在钙基蒙脱石上的吸附解吸行为。结果表明:吸附容量和去除率主要受铜离子初始浓度及溶液pH值的影响,当初始浓度为40.84 mg/L且pH6时,99%的铜离子可被蒙脱石吸附去除。吸附过程符合伪二级动力学和Langmuir等温模型,线性相关性均在99%以上,吸附容量的实验值与Langmuir模型计算值相吻合。吸附的铜离子很容易在高浓度的氯化钠溶液中解吸出来,解吸率可达90%。连续4次吸附解吸后蒙脱石仍保持较强的吸附能力,且每次解吸后因层间为更易交换的钠离子,使前两次再生的蒙脱石吸附容量高于首次钙基蒙脱石的吸附容量。利用XRD对吸附及解吸前后的蒙脱石进行表征,结果与上述实验一致。

Adsorption-desorption of Cu(II)on Ca-Montmorillonite

Removal of heavy metal ions by adsorption is considered to be one of the most important operation for water decontamination. However,the industrial application of this method is limited by the desorption efficiency of adsorbent. The adsorption and desorption of Cu(II)on Ca-montmorillonite have been investigated in this study. The adsorption capacity and removal efficiency are mainly influenced by the initial concentration of Cu(II)and pH of solution. The maximum removal efficiency of Cu(II)reaches 99% at the initial concentration of 40. 84 mg/ L when the pH of solution is above 6. Experimental results indicate that the adsorption reactions of Cu(II)on Ca-montmorillonite agree well with the second-order kinetics and the Langmuir isotherm model. The regression coefficient is above 0. 99 and the adsorption capacity from calculation fits well with the experimental data. Cu(II) on Ca-montmorillonite is easily desorbed by the NaCl solution of high concentration and the desorption efficiency could reach to 90%. The montmorillonite keeps excellent absorption ability after 4-time consecutive adsorp-tion-desorption. Furthermore,the previous two adsorption capacities of montmorillonite after desorption are higher than Ca-montmorillonite because of the easier exchangeable cation of Na+on montmorillonite. Samples before and after adsorption or desorption have been characterized by X-ray diffraction,which are consistent with the results mentioned above.