聚乙烯亚胺-羧甲基纤维素的合成及对金属离子的吸附性能

Preparation of Polyethyleneimine-Carboxymethyl Cellulose and Its Adsorption Properties for Metal Ions

以羧甲基纤维素（CMC）为基质,用戊二醛（GA）做交联剂,将聚乙烯亚胺（PEI）交联到羧甲基纤维素上制得聚乙烯亚胺-羧甲基纤维素吸附剂（PEI-CMC）。采用傅里叶变换红外光谱、扫描电镜、X射线光电子能谱对PEI-CMC的结构进行了表征,测定了其对Cu2＋、Pb2＋和Cd2＋的吸附性能,并研究了pH 值、时间、金属离子的初始浓度对吸附的影响。结果表明,当CMC、PEI和GA的反应比为1g∶5mL∶20mL,反应温度为25℃,反应时间为3h时,合成的PEI-CMC的含氮量为13.23%。当CMC和PEI的反应比为1g∶5mL时,随着戊二醛（质量分数2.5%）的加入量增加,PEI-CMC的产率先增大后降低。在pH 值1～14的范围内,溶液酸碱度的变化对PEI-CMC 的交联度没有影响。PEI-CMC 吸附剂对Cu2＋ 、Pb2＋和Cd2＋ 的吸附量在实验范围内随pH 升高而增加。PEI-CMC对Pb2＋和Cu2＋、Cd2＋的吸附在90min和180min后分别达到平衡,吸附动力学符合准二级反应动力学模型。随着Cu2＋、Pb2＋和Cd2＋初始浓度的增加,PEI-CMC对Cu2＋、Pb2＋和Cd2＋的吸附量开始时快速增加,而后达到饱和,吸附等温数据符合Freundlich模型,最大吸附容量分别为Cu2＋ 250.0mg/g、Pb2＋ 635.9mg/g、Cd2＋ 142.8mg/g。

The adsorbent of polyethylenei mine carboxymethyl cellulose （PEI-CMC） was successfully prepared with crosslinking polyethylenei mine （PEI） and carboxymethyl cellulose （CMC） by glutaraldehyde. Synthesized PEI-CMC was characterized by FT-IR, SEM and XPS. The adsorption properties of PEI-CMC for Cu2＋,Pb2＋ and Cd2＋ ions were evaluated. Various factors affecting the uptake behavior such as pH, contact time and initial concentration of the metal ions were investigated. The results show that the nitrogen content of prepared PEI-CMC is 13.23% at CMC, PEI and GA reaction ratio of 1 g∶5 mL∶20 mL, temperature 25 ℃ for 3h. As the 2.5% GA increasing, the yield of PEI-CMC firstly increases and then decreases when CMC and PEI reaction ratio is 1 g∶5 mL. In the pH range of 1～14, pH of the solution has no effect on the crosslinking degree of PEI-CMC. With the increase of pH value, the uptake capacity of the three metal ions increases. Pb2＋ adsorption capacity is rapid initially, and reaches equilibrium after approximately 90 min. Cu2＋ and Cd2＋ions adsorption reaches equilibrium after 180 min. The adsorption kinetics follows the mechanism of the pseudo second order equation for all systems. For the three metal ions, obviously the uptake capacity of PEI-CMC increases with increasing the initial concentration of the metal ions and becomes slow gradually. The best interpretation for the equilibrium data is given by Freundlich isotherm, and the maximum adsorption capacities are 250.0 mg/g, 635.9 mg/g and 142.8 mg/g for Cu2＋, Pb2＋ and Cd2＋ions, respectively.