乙二胺改性淀粉GMA共聚物对Pb(Ⅱ)的吸附性能

Adsorption of Pb(Ⅱ) on copolymer of glycidyl methacrylete grafted on starch modified with ethylenediamine

以木薯淀粉为原料,通过接枝共聚、环氧开环反应,得到富含—NH2官能团的新型氨基改性淀粉（AMS）,用FT-IR、SEM和XRD对其结构进行表征。在静态条件下,研究了AMS对水溶液中Pb（Ⅱ）的吸附性能和吸附热力学,考察了溶液pH值、吸附时间、Pb（Ⅱ）初始浓度及温度对AMS吸附性能的影响。结果表明：pH值对AMS的吸附性能有显著影响;该吸附是一个快速吸附过程,符合准二级动力学方程,以化学吸附为主;吸附等温线用Langmuir方程拟合效果优于Freundlich方程;分离因子在0~1之间;在初始浓度100mg.L-1,pH值为6.0、25℃下的最大吸附容量为0.481 mmol.g-1;吸附为自发、吸热的熵增加过程,升温有利于吸附;AMS可重复使用5次以上。

A novel amino modified starch（AMS）adsorbent modified with ethylenediamine was obtained via grafting polymerization and ring-opening reactions using cassava starch as raw material.The adsorbent was characterized by FT-IR,XRD and SEM.The absorption performance and adsorption thermodynamics were studied in the adsorption process of Pb（Ⅱ）ions in aqueous solution on the AMS.The effects of pH value,adsorption time,temperature and initial concentration were investigated.It is found that the effect of pH on the adsorption is significant.The adsorption is fast and follows a pseudo-second order process.Chemical adsorption is the main process and the equilibrium isotherm is well described by the Langmuir model rather than the Freundlich model.The separation factors are in the range of 0—1.The maximum adsorption capacity of 0.481 mmol·g-1 is obtained at initial concentration of 100 mg·L-1,pH 6.0 and 25℃.The adsorption is a spontaneous and endothermic process with increased entropy,and higher temperature will benefit the adsorption.The adsorbent can be reused for more than five cycles without decreasing its adsorption efficiency.