贝壳粉对Cd(Ⅱ)的吸附性能研究

为了研究贝壳粉对Cd~(2+)的吸附性能及最佳吸附条件,采用静态吸附实验研究了Cd~(2+)初始浓度、吸附剂用量、温度、pH、吸附时间以及离子强度对贝壳粉吸附Cd~(2+)性能的影响。结果表明:在不同Cd~(2+)初始浓度下,随着吸附剂用量的增加,贝壳粉对Cd~(2+)的吸附量呈现出先强烈吸附后逐渐缓和的趋势,符合准一级动力学模型和准二级动力学方程。Temkin和Langmuir模型均能较好地描述贝壳粉对Cd~(2+)的等温吸附过程,约30 min达到平衡,为自发的吸热反应,最大饱和吸附量为161.75 mg·g~(-1)。随着溶液pH值增加,贝壳粉对Cd~(2+)的吸附性能也随之增大,当pH≥5时趋于稳定。随着Ca~(2+)和Mg~(2+)浓度增大,贝壳粉对Cd~(2+)的吸附性能逐渐减弱,最大降幅分别达到15.19%和14.44%。

Adsorption performance of cadmium onto shell powder

To study the adsorption mechanisms and the optimum adsorption conditions of Cd2+onto shell powder, batch experiments were conducted to investigate the effects of initial Cd2+concentration, adsorbent dose, pH, temperature, time, and ionic strength on Cd2+adsorption onto the shell powder. The results showed that the adsorption of Cd2+onto the shell powder rapidly increased and then decreased gradually with the increase of sorption agent under different initial Cd2+concentration, and the adsorption fitted well to pseudo-first-order and pseu-do-second-order kinetics. The isothermal adsorption was well described by the Temkin isotherm and the Langmuir isotherm. The adsorption process of Cd2+was a spontaneous and endothermic reaction that achieved adsorption equilibrium in only 30 min, and the maximum equilib-rium adsorption capacity was 161.75 mg·g-1. The adsorption of Cd2+onto the shell powder increased with increasing pH, and then stabilized when the pH was≥5. With increasing concentrations of Ca2+and Mg2+, the adsorption properties of the shell powder gradually decreased, with maximum reductions of 15.19%and 14.44%, respectively, compared with the control group.