PBMA/GMA-SiO2吸附剂的制备及其高效去除铅离子

Preparation of PBMA/GMA-SiO2 adsorbent and its efficient removal of lead ions

摘要:

以甲基丙烯酸丁酯(BMA)和甲基丙烯酸缩水甘油酯(GMA)功能化的纳米SiO2为单体，通过可逆加成-断裂链转移自由基聚合(RAFT)法制备了PBMA/GMA-SiO2有机/无机复合吸附材料，并将其用于吸附含Pb2+ 的水溶液。考察了吸附时间、温度、pH 值以及Pb2+初始浓度对吸附效果的影响，并对其吸附动力学和热力学特性进行了探讨。结果表明，PBMA/GMA-SiO2对Pb2+具有良好吸附性能，其对Pb2+的饱和吸附量为423.84 mg/g，吸附最佳pH为5-6，平衡时间为1 h，去除率随Pb2+初始浓度的减小而增加。优化实验条件下，50 mg吸附剂在298K时，对pH=6的50 mL 0.02 g/L溶液的去除率高达100%。热力学和动力学过程模拟结果表明，吸附的动力学过程比较符合准二级动力学速率方程，Langmuir等温方程比Freundlich等温方程更适合于描述此吸附行为。颗粒内扩散过程是吸附速率的控制步骤，但不是唯一的速率控制步骤。吸附剂经过5次脱附、吸附后，依然具有较强吸附Pb2+的能力。

Abstract:

PBMA/GMA-SiO2 adsorbent was synthesized via RAFT polymerization by using butyl methacrylate(BMA) and GMA -functionalized silica particles as monomers. The effects of pH,contact time and initial Pb2+ concentration on adsorption properties were evaluated, as well as adsorption thermodynamics and kinetics were also examined. The results show that the PBMA/GMA-SiO2 adsorbent was effective for Pb2 removal from water, the maximal adsorption capacity for Pb2+ was found to be 423.84 mg/g, the optimum pH value for Pb2+ removal is 5 to 6, and absorption time is 1 h, the removal efficiency increased with the decreasing of initial Pb2+ concentration. Under optimized conditions, 50 mg sorbent could remove 100% of Pb2+ from 50 mL 0.02 g/L Pb2+ solution at pH = 6 and 298K. The adsorption kinetics could be best described by pseudo second-order kinetic model, compared with the Freundlich isotherm equation, the Langmuir isotherm equation is more appropriate to describe the adsorption behavior. The adsorption rate is not only controlled by intra-particle diffusion but also by extra-particle diffusion. Besides, the materials still show good adsorption capacity to Pb2+ after five times of desorption and adsorption.