伊利石对U(Ⅵ)的吸附行为研究

Study on sorption behavior of illite to U(Ⅵ)

以伊利石为吸附剂,采用静态实验方法探究了接触时间、吸附剂质量、U(Ⅵ)初始浓度、pH、阴阳离子及腐植酸对U(Ⅵ)在伊利石上吸附的影响。实验结果表明,伊利石与U (Ⅵ)接触10 h后反应基本达到平衡,当U (Ⅵ)初始浓度为30μg/m L、溶液pH为5~6、吸附剂质量为0. 03 g时,伊利石对U(Ⅵ)的吸附效果最好。阴阳离子对伊利石吸附U(Ⅵ)影响显著,阳离子中Ca2+对吸附有超强的抑制作用,而K+有一定的促进作用;阴离子中CO2-3、HCO-3对吸附的抑制作用较强。腐植酸的加入也促进了伊利石对U(Ⅵ)的吸附,且吸附效果与腐植酸浓度成正相关。对吸附前后的伊利石进行表征,探讨U(Ⅵ)在伊利石上的吸附动力学规律,结果表明,准二级动力学模型可以更好地描述U(Ⅵ)在伊利石上的吸附过程,相关系数达0. 998,吸附机理主要为离子交换和表面络合作用。

Taking illite as adsorbent,the effects of contact time,adsorbent mass,initial concentration of U(Ⅵ),pH,anion,cation and humic acid on adsorption of U(Ⅵ)on illite are investigated by static test method.The experimental results show that the reaction can basically reach equilibrium after contacting between illite and U(Ⅵ)for 10 h.Illite shows the best adsorption effect on U(Ⅵ)when the initial concentration of U(Ⅵ)is 30μg/mL,the pH of solution is in the range of 5-6,and the dosage of adsorbent is 0.03 g.Both anions and cations have a significant effect on the adsorption of U(Ⅵ)by illite.Ca2+among cations has a strong inhibitory effect on the adsorption,while K+has a certain promoting effect.Both CO2-3 and HCO-3 among anions have a strong inhibitory effect on the adsorption.The addition of humic acid can also promote the adsorption of U(Ⅵ)by illite,and the adsorption effect is positively correlated with the concentration of humic acid.The illite before and after adsorption is characterized by FT-IR,and the adsorption kinetics of U(Ⅵ)on illite is further explored.The results show that the pseudo-second-order kinetic model can better describe the adsorption process of U(Ⅵ)on illite with a correlation coefficient of 0.998.Ion exchange and surface complexation are thought as the main adsorption mechanism.