PAA/SiO2材料对含铜废水吸附性能研究

摘要

以γ-氯丙基三甲氧基硅烷为偶联剂,将聚烯丙基胺(PAA)接枝到硅胶表面,合成了聚烯丙基胺硅胶材料(PAA/SiO2),研究了其对Cu2+的吸附热力学、动力学和选择特性.结果表明,合成的PAA/SiO2材料的胺基含量为1.81mmol·g-1;溶液pH值对PAA/SiO2的铜吸附量影响显著,当溶液pH值为4时,材料的铜吸附量达到0.397 mmol·g-1;测定的Cu2+吸附平衡数据符合Langmuir模型,计算了吸附过程的热力学参数,结果表明吸附过程为吸热过程,升温有利吸附的进行;吸附动力学数据可用拟二级吸附动力学方程描述,得到的吸附速率常数与溶液初始浓度有关；铜锌竞争吸附结果表明PAA/SiO2材料对Cu2+有更强的吸附能力,对铜的选择性系数在2～4之间;另外,PAA/SiO2材料容易洗脱再生,5次吸附再生循环后,其铜吸附量维持在91.1％以上.%Poly(allylamine)-grafted silica gel (PAA/SiO2) with amino group content of 1.81 mmolg"1 was synthesized by using ^-chioropropyltrimethoxysilane as coupling reagent and poly(allylamine) as surface-modifying reagent. The thermodynamics, kinetics and selectivity of Cu2+ adsorption by prepared PAA/SiO2 were studied. The experimental results show that the pH value of Cu2+ solution affects the adsorption capacity of the PAA/SiO2 significantly, and its adsorption capacity for Cu2+ at pH=4.0 is 0.397 mmol-g"1. The measured adsorption equilibrium data for Cu2+ could fit the Langmuir model well. Trie calculated results of Cu2+ adsorption thermodynamic parameters of PAA/SiO2 show that the Cu2+ adsorption is endothermic spontaneous process, and increasing temperature is conductive to the Cu2+ adsorption. It was found that the adsorption kinetic data could be fitted by the pseudo-second-order kinetic equation, and the fitted kinetic constants are related with the initial solution concentration. The results of its selectivity study show that the PAA/SiO2 possesses recognizing ability for Cu2+ and its selectivity coefficient is about 2-4 in relation to Zn2+. Besides, the synthesized PAA/SiO2 is easy to be regenerated and can still maintain up to 91.1% of its initial Cu2+ adsorption capacity after five adsorption-regeneration cycles.