核桃壳粉对水溶液中Pb^(2+)的吸附  

Adsorption of Pb^(2+) from aqueous solution by walnut shell powder

作　　者：许振[1] 李云春[1] 姜友军[1] 孟令银[1] 

机构地区：[1]四川农业大学生命科学与理学院,雅安625014

出　　处：《环境工程学报》2012年第12期4504-4512,共9页Chinese Journal of Environmental Engineering

基　　金：四川省教育厅科研重点项目(09ZA062);四川农业大学"大学生创新性实验计划"基金(111062632)

摘　　要：实验通过间歇吸附方式研究了核桃壳粉对水溶液中Pb2+的吸附特性,探讨了核桃壳粉粒径及用量、溶液pH、Pb2+初始浓度等参数对吸附的影响,并讨论了吸附过程的热力学和动力学特征。结果表明,核桃壳粉对Pb2+吸附的最佳pH为5.0,去除率随吸附剂粒径的减小、用量的增加、Pb2+初始浓度的减小而增加。优化实验条件下,0～0.3 mm 15 g/L的吸附剂在298 K时,对pH=5的50 mL 50 mg/L Pb2+溶液的去除率达96.98%。核桃壳粉对Pb2+的吸附等温线符合Sips模型,在283、293和303 K的最大吸附量分别为18.25、18.27和20.94 mg/g。吸附过程是放热的、混乱度减小的自发过程,且符合准二级动力学模型。吸附速率常数随温度升高而减小,在293和303 K时分别在90和120 min基本达到平衡。结合FTIR和SEM手段发现核桃壳对Pb2+的吸附以物理吸附为主,同时包括离子交换、螯合等化学吸附以及颗粒内扩散步骤,是一个复杂的过程。In this study, the adsorption of Pb^2＋ from aqueous solution by walnut shell powder was investiga- ted. The effect of experimental parameters, such as sorbent size, dosage, pH and initial Pb^2＋ concentration,as well as adsorption thermodynamics and kinetics were also examined. The results show that the removal efficiency increased with the decreasing sorbent size, increasing sorbent dosage and initial Pb2＋ concentration. Under opti- mized conditions, 0 - 0.3 mm 15 g/L sorbent could remove 96.98% of Pb2 ＋ from 50 mL 50 mg/L Pb^2＋ solution at pH = 5 and 298 K. The experimental data closely followed Sips isotherms, with adsorption capacity of 18.25, 18.27 and 20.94 mg/g at 283, 293 and 303 K, respectively. The overall adsorption process was exothermic, entropy reduced and spontaneous. The adsorption kinetics followed the pseudo-second order model, and the rate constant decreased with the increasing temperature. The adsorption equilibrium could be reached within 90 and 120 min at 293 and 303 K, respectively. Combined with FTIR and SEM methods, the process of adsorption Pb^2＋ on walnut shell powder was found to be complex and dominated by physical adsorption, accompanied with minor ion exchange, chelation and intra-particle diffusion process.

关 键 词：核桃壳粉 PB2+ 吸附 等温线 热力学 动力学 

分 类 号：X703[环境科学与工程—环境工程]