采用静态法研究了铀(U(Ⅵ))在高岭土上的吸附特性,探讨了pH、离子强度、接触时间、温度、腐殖酸等对U(Ⅵ)在高岭土上吸附的影响.以宏观吸附实验为基础,对高岭土进行X线衍射(XRD)和扫描电镜(SEM)表征,并讨论了铀(U(Ⅵ))在高岭土上的吸附动力学及热力学行为.结果说明,准二级动力学模型可以用来描述铀在高岭土上的吸附.通过对溶液pH值和离子强度因素的研究,溶液pH值对铀的吸附影响比离子强度对铀的吸附影响更大.在较低pH值下,腐殖酸对吸附有加强的作用;在较高pH值下,腐殖酸对吸附有抑制作用.Freundlich模型可较好地描述高岭土对U(Ⅵ)的吸附过程.高岭土对U(Ⅵ)的吸附为自发且吸热的过程,主要是表面单分子层吸附.
关键词：
高岭土; 铀; 吸附; 动力学; 热力学
By static adsorption experiments,the effects of pH,ionic strength,adsorption time,solid-liquid ratio,temperature,humic acid on the adsorption of U(Ⅵ)onto kaolin were studied.Based on macroscopic adsorption experiments,the adsorption process was analyzed by thermodynamics and kinetics methods,and the kaolin samples were characterized by X-ray diffraction and scanning electron microscopy.The results show that pseudo-second-order kinetic model can be used to describe the adsorption of uranium on kaolin.Through the study of pH and ionic strength,the effect of pH on the adsorption of uranium is greater than the effect of the ionic strength on the adsorption of uranium.The presence of HA reduces the adsorption in a high pH range,while enhances the adsorption at low pH values.The adsorption of U(Ⅵ)onto kaolin could be described by Freundlich isothermal adsorption equation.The adsorption of U(Ⅵ)onto kaolin is an endothermic process,mainly occurs on the surface as a monomolecular layer.
[1] 罗上庚.核废物的安全和环境影响[J].安全与环境学报,2001,1(02):16-20. LUO S G.Safety and environmental impact of nuclear waste[J].Journal of safety and Environment,2001,1(02):16-20.
[2] LI Q F,LIU M X,KANG J M,et,al.Advances in interaction between micro organ-ism and radioactive nuclide[J].Environmental Scienceand Technology,2008,31(10):67-70.DOI:10.3969/j.issn.1003-6504.2008.10.017.
[3] 周书葵,曾光明,刘迎九,等.改性羧甲基纤维素对铀吸附机理的试验研究[J].中国环境科学,2011,31(9):1466-1471.
[4] 陆朝阳,沈莉莉,张全兴.吸附法处理染料废水的工艺及其机理研究进展[J].工业水处理,2004,24(3):12-16. LU Z Y,SHEN L L,ZHANG Q X.Research development of technics and mechanism of dye wastewater treatment by adsorption[J].Industrial Water Treatment,2004,24(3):12-16.
[5] LI S Y,XIE S B,WANG J L,et,al.Adsorption properties of clay for uranium in waste water[J].Chemical Environmental Protection,2006,26(6):459-462.
[6] INOUE S,KIRIYAMA K,HATANNAKA Y,et al.Adsorption properties of an activated carbon for 18 cytokines and HMGB1 from inflammatory model plasma[J].Colloids and Surfaces B:Biointerfaces,2015,126:58-62.DOI:10.1016/j.colsurfb.2014.12.015.
[7] REN X M,WANG S W,YANG S T.Influence of contact time,pH,ionic strength and temperature on sorption of U(Ⅵ)onto MX-80 bentonite[J].J.Radioanal Nucl.Chem.,2010,283(1):253-259.DOI:10.1007/s10967-009-0323-0.
[8] 吴自强.高岭土应用技术[J].化学建材,1996,12(2):88-89.
[9] EVANS N,WARWICK P,LEWIS T,et al.Influence of humic acid on the sorption of U(Ⅵ)to kaolin[J].Environmental Chemistry Letters,2011,9(1):25-30.DOI:10.1007/s10311-009-0241-y.
[10] 宋文玉,降青梅,刘亚东,等.铬(Ⅲ)离子催化铈(Ⅳ)离子氧化异丁醇的反应动力学及机理[J].河北大学学报(自然科学版),2004,24(6):594-599. SONG W Y,JIANG Q M,LIU Y D,et,al.Kinetics and mechanism of chromium(Ⅲ)ion catalysis cerium Ⅳ)ions oxidation isobutanol[J].Journal of Hebei University(Natural Science Edition),2004,24(6):594-599.
[11] SHAUHA M S,SARWAR M I,QADEER R,et,al.Adsorption of strontium ions from aqueous solution on Pakistani coal[J].Journal of Radioanalytical and Nuclear Chemistry,2005,265(1):73-79.DOI:10.1007/s10967-005-0789-3.
[12] AKSU Z.Application of biosorption for the removal of organic pollutants:A review[J].Process Biochemistry,2005,40(3-4):997-1026.DOI:10.1016/j.procbio.2004.04.008.
[13] 熊正为,王玉清,郭成林,等.蒙脱石吸附铀机理实验研究[J].湖南师范大学(自然科学学报),2007,30(3):75-79. XIONG Z W,WANG Y Q,GUO C L,et,al.Experimental study on the mechanism of adsorption of montmorillonite[J].Journal of natural science of Hunan Normal University,2007,30(3):75-79.
[14] XIE Z F,HE X C,XIA J H.Adsorption thermodynamics and dynamic of polyamide to picric acid[J].Chem Res,2003,12(4):53-56.
