阳离子交换纤维对铟的吸附解吸性能

Adsorption and desorption properties of indium(Ⅲ) on cationic exchange fiber

用阳离子交换纤维吸附的方法研究了铟的富集及回收。测定了溶液的pH值、温度、吸附时间等因素对吸附的影响,研究了吸附的热力学和动力学特性。结果表明阳离子交换纤维在pH=2～3.5时,吸附能力最好,等温吸附服从Freundlich经验式,吸附动力学符合Ho准二级速率方程,颗粒内扩散是速率控制步骤之一,膜扩散也共同影响着吸附过程。在287～350K条件下,铟吸附摩尔分数为0.6～1.2mmol/g的吸附焓变为35.68～32.36kJ/mol,自由能变为-16.63～-21.10kJ/mol,吸附熵变为181.9～156.6J/(K.mol),吸附速率常数为k287K=0.09379g/(mg.min),k300K=0.1159g/(mg.min),k321K=0.4046g/(mg.min)和k350K=0.6678g/(mg.min)。吸附活化能为28.28kJ/mol。303K下用0.5mol/L的硫酸溶液可定量洗脱,洗脱率达99%。

The enrichment and recovery of indium（Ⅲ） by cationic exchange fiber adsorption method were investigated.With the measurement of related parameters such as pH,temperature and adsorption time,the adsorption kinetic and the thermodynamic of sulfuric acid group modified polystyrene were studied.The results show that the maximum adsorptive capacity of cationic exchange fiber can be attained at pH=2-3.5;the adsorption behavior of cationic exchange fiber for indium（Ⅲ） obeys the freundlich isotherm;the adsorption kinetic data fit the Ho pseudo-second order rate equation,and besides the intra-particle diffusion,other processes such as film diffusion also affect the rate of adsorption simultaneously.At 287-350K the adsorption mol fraction of indium（Ⅲ） is 0.6-1.2mmol/g,the changes of adsorption enthalpy is 35.68-32.36kJ/mol,the free energy is-16.63——21.10kJ/mol,the entropy of adsorption is 181.9-156.6J/（K·mol）,the adsorption rate constant are k287K=0.09379g/（mg·min）,k300K=0.1159g/（mg·min）,k321K=0.4046g/（mg·min） and k350K=0.6678g/（mg·min）.The adsorption activity energy is 28.28kJ/mol.At 303K,99% of the indium（Ⅲ） adsorbed by the cationic exchange fiber can be easily and quickly eluted with 0.50mol/L sulphuric acid solution.