余甘子固定化单宁的制备及其对Ge(Ⅳ)、Ga(Ⅲ)及In(Ⅲ)的吸附特性研究

Preparation of Phyllanthus emblica Immobilized-tannin and Its Adsorption Characteristics to Ge (Ⅳ),Ga (Ⅲ) and In (Ⅲ)

以戊二醛为交联剂,壳聚糖为聚合物基质,固化余甘子单宁制备一种固体吸附材料余甘子固定化单宁(PEIT),并采用FT-IR、DSC、TG对PEIT的结构和热性质进行了表征。研究结果表明:余甘子单宁通过戊二醛与壳聚糖基质产生了交联,最佳制备条件为2 g余甘子单宁,m(戊二醛)∶m(余甘子单宁)1∶4,m(壳聚糖)∶m(余甘子单宁)1.5∶1,反应液初始pH值4,55℃反应3 h。将制备的PEIT用于吸附金属离子,结果显示其对Ge(Ⅳ)、Ga(Ⅲ)和In(Ⅲ)有良好的吸附效果,当pH值为4时,In(Ⅲ)吸附量最大;当pH值为3时,Ge(Ⅳ)和Ga(Ⅲ)吸附量最大;对这3种金属离子的吸附符合准二级动力学方程,说明其吸附机理为化学吸附;吸附过程对温度并不敏感,且最佳吸附温度为30℃。吸附等温线符合Langmuir等温线模型,证明其表面存在均匀的吸附位点,且主要是单分子层吸附,Ga(Ⅲ)、In(Ⅲ)和Ge(Ⅳ)的最大吸附量分别为67.65、70.00和54.11 mg/g。

A solid adsorption materials,Phyllanthus emblica immobilized-tannin(PEIT),was prepared based on glutaral as crosslinking agent and chitosan as polymer matrix.The structure and thermal properties of PEIT were characterized by using FT-IR,DSC and TG.The results showed that P.emblica tannins were immobilized on chitosan by glutaral crosslinking.The optimum conditions for preparing PEIT were found as follows:the mass ratio of glutaral to tannin 1∶4,the mass ratio of chitosan to tannin 1.5∶1,the initial pH value of the reaction solution 4.0,and 55℃ for 3.0 h.The result of using PEIT to adsorb metal ions showed that PEIT has good adsorption effection on Ge(Ⅳ),Ga(Ⅲ),In(Ⅲ).The PEIT demonstrated the maximum adsorption efficiency at pH 4.0 for In(Ⅲ)and pH 3.0 for Ge(Ⅳ)and Ga(Ⅲ).The adsorption for these three metal ions followed pseudo second-order kinetics,indicating the chemisorption nature.The adsorption process of PEIT to Ge(Ⅳ),Ga(Ⅲ),In(Ⅲ)was not sensitive to temperature,and the best adsorption temperature was 30℃.The adsorption isotherms all fitted well with the Langmuir model,PEIT was based on a monolayer adsorption onto homogenous surfaces by uniformly distributed adsorption sites,and the calculated maximum adsorption capacities were 67.65,70.00 and 54.10 mg/g for Ga(Ⅲ),In(Ⅲ),Ge(Ⅳ),respectively.