粟米糠吸附Pb^(2+)的关键因素交互效应及吸附机理研究  

Adsorption of Pb^(2+) in aqueous solutions by millet chaff: interactive effects between the key factors and mechanism study

作　　者：冀泽华 冯冲凌[1] 李刘刚 

机构地区：[1]中南林业科技大学环境科学与工程研究所,长沙410004

出　　处：《环境化学》2017年第1期123-132,共10页Environmental Chemistry

基　　金：国家"十二五"科技支撑计划项目(2012BAC09B03);湖南省科技计划项目(2015SK20023);湖南省环境科学与工程重点学科建设项目;中南林业科技大学研究生科技创新基金(CX2015B29)资助~~

摘　　要：采用响应面法(Box-Behnken design,BBD)考察粟米糠吸附Pb^(2+)的不同因素(p H值、Pb^(2+)初始浓度、吸附剂浓度和吸附时间)对吸附过程的影响及交互效应,并通过等温吸附和表征分析研究吸附过程的热力学特征及其吸附机理.结果表明,p H值与Pb^(2+)初始浓度和吸附剂浓度交互效应显著,Pb^(2+)初始浓度与吸附时间的交互效应显著.使用等温吸附模型拟合吸附过程发现,Langmuir和Freundlich模型拟合结果较好,该过程为物理吸附与化学吸附共同作用,293、298、303、308 K条件下的粟米糠最大吸附量qm分别为10.33、10.56、11.10、11.22 mg·g-1,其对Pb^(2+)吸附能力随温度上升而提高.对吸附热力学参数ΔG、ΔH与ΔS计算表明该过程为吸热的自发反应,随反应进行体系混乱度增加.SEM和FTIR分析表明,粟米糠吸附Pb^(2+)前后表面形态发生明显改变,羟基、羧基、醇羟基等基团在粟米糠吸附Pb^(2+)中起主要作用.The Box-Behnken design（ BBD） methodology including four factors： p H,initial Pb^2＋concentration,adsorbent dosage and contact time was employed to study the adsorption process of Pb^2＋from aqueous solution by millet chaff. The effects of four factors on the adsorption and interactive effects between the factors were evaluated. The results indicated that the interactive effects between p H and initial Pb^2＋concentration,p H and adsorbent dosage,and initial Pb^2＋concentration and contact time were significant. The equilibrium adsorption analysis using different isotherm models showed that the processes of Pb^2＋adsorption on millet chaff were dominated by chemical adsorption though physical adsorption phenomena were also observed. The maximum adsorption capacity qmof millet chaff were found to be 10. 33 mg·g-1,10.56 mg·g-1,11.10 mg·g-1and 11. 22 mg·g-1at293 K,298 K,303 K and 308 K,respectively,indicated that the adsorption capacity of millet chaff increased with the increase of temperature. Thermodynamic parameters such as ΔG,ΔH and ΔSwere calculated and showed that the adsorption process was endothermic and spontaneous,while the entropy of the system increased. The SEM and FTIR spectra analysis indicated that surface morphology of millet chaff were significantly different after adsorption procedures,and the functional groups responsible for Pb^2＋binding were hydroxyl,carboxyl,and alcoholic hydroxyl.

关 键 词：粟米糠 铅离子 响应面法 交互效应 热力学 

分 类 号：X703[环境科学与工程—环境工程] O647.3[理学—物理化学]