乙二胺硅胶材料对铜和锌离子的动态吸附

合成了胺基含量为1.35 mmol/g的乙二胺硅胶材料(EDA/SiO2),研究了EDA/SiO2对Cu2+和Zn2+的动态吸附及动态竞争吸附。结果表明,铜溶液流量和初始浓度对材料动态吸附性能有显著影响,随着溶液初始浓度的增大、流速的加快,穿透时间明显缩短。动态吸附实验结果符合Thomas模型,计算结果显示,铜溶液初始浓度由1.99 mmol/L增大至10.00 mmol/L时,模型平衡吸附容量q0从0.272 mmol/g增大至0.476 mmol/g,影响显著;流量对q0影响不显著。溶液流量和初始浓度对吸附速率常数kTh均有影响,随溶液流量增大、初始浓度的降低,速率常数值增大。在单一体系中,EDA/SiO2对Cu2+和Zn2+的工作吸附量分别为0.340和0.127 mmol/g,混合体系的吸附量均小于单一体系中的吸附量,并且对Zn2+的吸附量下降显著,表明EDA/SiO2对Cu2+的吸附能力强于Zn2+。6次循环实验表明,盐酸和氨水可对EDA/SiO2材料实现再生,再生后材料对铜的吸附容量和穿透时间的下降幅度不大,可重复使用。

Dynamic Adsorption of Copper and Zinc Cations on Ethylenediamine-grafted Silica Gel

Ethylenediamine-grafted silica gel(EDA/SiO2) with the amino content of 1.35 mmol/g was synthesized. Its adsorption capacities toward copper and zinc cations in both single-component and binary-component aqueous solutions were studied. The influences of the flow rate and initial concentration of metal cations in the solution on the adsorption time were quantitatively determined. The results showed that the adsorption time decreased dramatically with the increase of the initial concentration of copper cations as well as the flow rate of the solution. The removal of copper cations by EDA/SiO2 column could be evaluated by the Thomas model. The initial copper concentration exerted significant effect on the Thomas saturation adsorption capacities(q0), which were increased from 0.272 mmol/g to 0.476 mmol/g in the initial concentration range of 1.99 mmol/L to 10.00 mmol/L. But no significant influence of the solution flow rate could be observed. The model rate constant kTh increased when the initial concentration was decreased or the flow rate of solution increased. In single component solutions, the adsorption capacities of EDA/SiO2 toward Cu(Ⅱ) and Zn(Ⅱ) were 0.340 mmol/g and 0.127 mmol/g, respectively. However, such adsorption capacities decreased in binary-component solution. The adsorption of zinc cation was decreased in the presence of copper cations, suggesting that the removal of copper was superior to that of zinc cations from aqueous solution. Furthermore, EDA/SiO2 could be regenerated by hydrochloric acid solution and ammonia water, and its adsorption capacity could be maintained even after regeneration for 6 times.