椰壳对水中Cu^(2+)的吸附性能研究

Removal of Cu^(2+) from Aqueous Solution by Coconut Shell

以椰壳为吸附剂,研究其对水溶液中Cu^(2+)的去除特性和过程机制.考察了吸附时间、温度、pH、椰壳投加量和共存阴离子对椰壳吸附Cu^(2+)的影响,并对吸附动力学、吸附热力学和等温吸附平衡进行探究.结果表明,椰壳可以快速吸附水中的Cu^(2+),接触30min即达到平衡吸附量的95%以上;吸附过程符合准二级动力学方程,颗粒内扩散不是其唯一限速步骤;等温吸附符合Langmuir方程,吸附过程是一个自发、放热、自由能减少的过程,温度升高不利于吸附进行,但温度对吸附的影响较小.pH、椰壳投加量和共存阴离子均影响的Cu^(2+)去除.

The removal characteristics and process mechanism of copper ions(Cu^(2+)) on the coconut shell in an aqueous solutions were studied. The effects of adsorption time, ambient temperature, solution pH, coconut shell dosages, and coexisting anion on the removal of copper ions from solutions by coconut shell were investigated. The adsorption behavior of copper ions by coconut shell was investigated using adsorption kinetics, adsorption isotherms and adsorption thermodynamics. The results showed that the coconut shell adsorbed Cu^(2+) from solution in a short time. The adsorption capacity reached more than 95% of the equilibrium adsorption capacity in 30 minutes. The adsorption kinetics and isotherms of Cu^(2+) onto coconut shell were fitted to the pseudo-second order model and to the Langmuir adsorption model. The intra-particle diffusion was not the only rate-limiting step of the adsorption process. The thermodynamic test results indicated that the adsorption process of Cu^(2+) by coconut shell was a spontaneous process with exothermic reaction and entropy decrease. Higher temperatures were not favorable for adsorption, although temperatures had little effects on adsorption. Solution pH, coconut shell dosages and coexisting anions also had effects on the adsorption of Cu^(2+) onto coconut shell.