粉末活性炭吸附水中ClO_2^-的热力学及动力学研究  

Thermodynamics and kinetics for sorption of chlorite on powdered activated carbon from water

作　　者：李新杰[1] 蒋丹丹[1] 张跃军[1] 

机构地区：[1]南京理工大学化工学院,江苏南京210094

出　　处：《南京理工大学学报》2013年第1期156-163,共8页Journal of Nanjing University of Science and Technology

摘　　要：为探讨水中粉末活性炭(PAC)吸附亚氯酸盐(ClO2-)的速率控制机制,在常规水处理的pH及温度下,通过烧杯搅拌实验对ClO2-在PAC上的等温吸附特性及吸附机理进行研究。用Langmuir和Freundlich模型对吸附等温线进行拟合,考察PAC对ClO2-吸附的性质及热力学行为;用伪一级、伪二级动力学模型以及颗粒内扩散、液膜扩散模型对吸附动力学数据进行分析,探讨该吸附过程的机理及速率控制机制。结果表明:在常规水处理条件下PAC对ClO2-的吸附是自发、吸热的化学吸附过程,适宜吸附的pH为6,吸附的表观活化能约为53 kJ/mol;平衡吸附量随温度和ClO2-初始质量浓度升高而增加,与Langmuir等温吸附模型和伪一级动力学模型相比,吸附等温线更符合Freundlich等温吸附规律,吸附动力学更符合伪二级动力学规律。研究结果表明了化学吸附反应是PAC吸附ClO2-速率的主要控制机制。To explore the rate-control mechanism of the sorption of chlorite on powdered activated carbon(PAC)from water,isotherms and mechanism of the sorption are studied by using the beaker stirring experiments under the pH and temperature of conventional water treatment.Thermodynamic characteristics of the sorption are explored using Langmuir and Freundlich models to fit the sorption isotherms data.Mechanism and rate-control steps of the sorption are studied using pseudo-first-order,pseudo-second-order,intraparticle diffusion and film diffusion kinetic models to analyze the kinetic data of the sorption.Results show that the sorption process of chlorite on PAC is found to be a spontaneous and endothermic process with the mechanism of chemisorption,and the apparent activation energy of the sorption is calculated to be about 53 kJ/mol.The sorption of chlorite on PAC is favorable at pH=6,and the equilibrium uptake of sorption increases with the increase of the initial chlorite concentration and the temperature.The sorption isotherms are well described by Freundlich model,and the sorption kinetics fits well the pseudo-second-order model.The results prove that the chemisorption reaction is the main rate-control mechanism of the sorption of chlorite on PAC.

关 键 词：粉末活性炭 亚氯酸盐 吸附 热力学 动力学 

分 类 号：TU991.2[建筑科学—市政工程]