改性水葫芦粉对水体中Hg^(2+)的吸附  

Adsorption of Hg^(2+) from aqueous solution by modified Eichhornia Crassipes Powder

作　　者：黄京晶 陈宏[1,2] 刘江[1] 何沅洁 HUANG Jingjing CHEN Hong LIU Jiang HE Yuanjie(College of Resources and Environment, Southwest University, Chongqing 400716, China Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China)

机构地区：[1]西南大学资源环境学院,重庆400716 [2]重庆市农业资源与环境研究重点实验室,重庆400716

出　　处：《环境工程学报》2017年第2期798-804,共7页Chinese Journal of Environmental Engineering

基　　金：国家科技支撑计划项目(2007BAD87B10)

摘　　要：通过二硫化碳(CS_2)对水葫芦粉进行改性,研究吸附时间、吸附剂浓度和溶液pH对改性前后水葫芦吸附溶液二价汞(Hg^(2+))的影响,并探讨其吸附动力学、热力学行为和除汞机理。结果表明:吸附剂浓度为2 g·L^(-1),溶液pH值为6,吸附时间180 min,改性水葫芦粉对Hg^(2+)浓度为2.0 mg·L^(-1)时的去除率大于93%;改性前后水葫芦粉对Hg^(2+)的吸附过程均符合拟二级动力学方程,化学吸附在整个吸附过程中起重要作用。吸附过程能够很好地用Langmuir方程拟合,吸附自由能变(ΔG)<0、吸附焓变(ΔH)>0、吸附熵变(ΔS)>0,表明改性水葫芦粉对Hg^(2+)的吸附过程是自发的吸热过程;动力学拟合和热力学研究表明改性水葫芦粉对Hg^(2+)的吸附既有物理吸附又有化学吸附。Eichhornia crassipes powder modified by CS2 was used for divalent mercury（ Hg^2＋） removal from aqueous media. Experiments were conducted to study the factors affecting the adsorption process,including the adsorbent concentration,solution pH,and contact time. The results showed that the removal rate of Hg^2＋under an initial Hg^2＋concentration of 2. 0 mg·L^-1was more than 93% under the following conditions： adsorbent dosage of 2 g·L^-1,solution pH of 6. 0,and reaction time of 180 min. The kinetics for two E. crassipes powders were well fit by the pseudo-second-order model,suggesting that the removal occurs by chemical adsorption.Thermodynamic analysis revealed that the adsorption process was well fit by the Langmuir isotherm,and the changes in Gibbs free energy（ ΔG）,enthalpy（ ΔH）,and entropy（ ΔG） were negative,positive,and positive,respectively,indicating that the adsorption of Hg^2＋onto the modified E. crassipes powder was endothermic and spontaneous. Dynamic and thermodynamic studies demonstrated that both chemical and physical adsorption contributed to the adsorption on Hg^2＋by the modified E. crassipes powder.

关 键 词：改性水葫芦粉 HG^2+ 动力学 等温线 热力学 

分 类 号：X703[环境科学与工程—环境工程] X705