羧甲基纤维素/聚乙烯亚胺气凝胶对Ni(Ⅱ)的吸附性能研究

Study on the adsorption performance of sodium carboxymethylcellulose/polyethyleneimine aerogel towards Ni(Ⅱ)

通过环氧氯乙烷交联羧甲基纤维素钠(SC)和聚乙烯亚胺(PEI)制备含胺基和羧基的多孔气凝胶(PSC),应用于废水中Ni(Ⅱ)的吸附。研究PSC的组成、溶液pH、处理时间和Ni(Ⅱ)初始浓度等因素对吸附的影响。结果表明:SC与PEI质量比为1∶5的PSC在pH=4.0的条件下具有最大吸附容量(>190mg/g);吸附行为符合准二级动力学和Freundlich等温吸附模型;在投料量为1.0g/L条件下,PSC可将实际水体中10mg/L的Ni(Ⅱ)降低至国家污水排放标准以下。X射线光电子能谱(XPS)、傅里叶红外光谱(FT-IR)和扫描电镜(SEM)等分析表明离子交换与Ni(Ⅱ)和羧基及胺基间的络合作用是吸附的主要机理。

Porous aerogels(PSC)containing amine and carboxyl groups were prepared by crosslinking sodium carboxymethylcellulose(SC)and polyethyleneimine(PEI)with epichlorohydrin.The PSC was applied for the removal of Ni(Ⅱ)from wastewater.The effects of factors including composition,solution pH,contact time and initial concentration of Ni(Ⅱ)on the adsorption were studied.The results showed that PSC with the mass ratio of SC to PEI of 1∶5 exhibited the maximum adsorption capacity(>190 mg/g)at pH=4.0.The adsorption followed the pseudo-second-order kinetic model and the Freundlich isothermal model.Under the condition of 1.0g/L dosage,the PSC could reduce the Ni(Ⅱ)of 10 mg/L in the actual water to below the national wastewater discharge standard.The analyses such as X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FT-IR)and scanning electron microscopy(SEM)revealed that the ion exchange and the complexation of Ni(Ⅱ)to carboxyl as well as amine groups were the main adsorption mechanism.