玉米酒糟对铅的吸附特征研究

Study on adsorption characteristics and kinetics of lead in water by corn vinasse

采用玉米酒糟为吸附剂,以其添加量、溶液pH、Pb^(2+)初始浓度、反应时间、反应温度为影响因素,研究玉米酒糟对水中铅吸附特征及机制。结果表明,随玉米酒糟用量增加,吸附量下降;随Pb^(2+)初始浓度的增加、溶液pH的升高、吸附时间的延长以及温度的升高,玉米酒糟对铅的吸附量增加;动力学分析发现,伪二级动力学方程拟合的平衡吸附量(q_(e)=41.49 mg/g)与实际平衡吸附量(q_(e)=41.69 mg/g)较为接近;Langmuir等温吸附模型可较好地拟合玉米酒糟对Pb^(2+)的吸附;热力学计算参数结果显示△G>0、△H>0、△S>0,表明玉米酒糟对铅的吸附为非自发吸热的熵增过程;玉米酒糟表面的羟基、羧基、羰基可通过表面官能团络合作用吸附Pb^(2+);玉米酒糟对铅的吸附机制包含物理吸附、络合作用、离子交换和静电吸附。

The characteristics and mechanisms to remove lead ion from aqueous solutions using corn vinasse through adsorption were investigated in batch experiments.The main parameters including the amount of adsorbent,pH value of solution,initial concentration of lead,contact time and contact temperature have been investigated.The results showed that as increase in the amount of corn vinasse,the adsorption capacity decreased,while increase in initial concentration of lead,pH value of solution and contact time will conducive to the adsorption amounts.The adsorption process could be effectively described by the pseudo-second-order kinetic equation.The equilibrium adsorption capacity(q_(e)=41.49 mg/g)is close to the actual equilibrium adsorption capacity(q_(e)=41.69 mg/g)by pseudo-second-order kinetic equation.The adsorption process was monolayer adsorption proved by Langmuir model.The thermodynamic test results of△G>0,△S>0,and△H>0 indicated that the adsorption process of Pb^(2+)by corn vinasse is a non-spontaneous process with endothermic reaction and entropy increments.The result of FTIR indicated that hydroxyl,carboxyl and carbonyl groups were involved in the adsorption process.the experimental result inferred that complexation,ion exchange electrostatic adsorption and physical adsorption were major adsorption mechanisms for binding lead ion to the sorbents.