海泡石表面化学特性及其对重金属Pb^(2+)Cd^(2+)Cu^(2+)吸附机理研究  

Surface Chemical Characteristics of Sepiolites and Their Adsorption Mechanisms of Pb^(2+),Cd^(2+) and Cu^(2+)

作　　者：徐应明[1] 梁学峰[1] 孙国红[2] 孙扬[1] 秦旭[1] 王林[1] 

机构地区：[1]农业部环境保护科研监测所污染防治研究室,天津300191 [2]天津农学院基础科学系,天津300384

出　　处：《农业环境科学学报》2009年第10期2057-2063,共7页Journal of Agro-Environment Science

基　　金：国家高技术研究发展计划(863计划)项目(2008AA06Z334);天津市自然科学基金项目(08JCYBJC02200);中央级公益性科研院所基本科研业务费专项资助

摘　　要：通过海泡石(SEP)和酸化海泡石(ASEP)表面酸碱反应与吸附平衡实验,研究了天然和酸化海泡石表面化学特性及其对重金属的吸附机理。结果表明,海泡石经过酸化处理后碱性下降,表面部分阳离子被质子取代,表面酸度增加,形成更多的表面吸附位,有利于对重金属离子的吸附作用。随着溶液pH由酸性向碱性的变化,重金属离子在海泡石表面的吸附机理表现为同晶置换与表面配位模式并存;当溶液pH呈弱碱性时,Pb和Cu均发生表面沉淀,其中Pb表现最为明显。采用等温吸附方法,研究了海泡石和酸化海泡石对Pb2+、Cd2+和Cu2+离子的吸附特性,结果表明,海泡石和酸化海泡石对Pb2+、Cd2+和Cu2+离子均有较好的吸附作用。海泡石对Pb2+、Cd2+和Cu2+离子的饱和吸附量分别为32.06、11.48和22.10mg·g-1,酸化海泡石对Pb2+、Cd2+和Cu2+离子的饱和吸附量分别为35.28、13.62和24.36mg·g-1。以物质的量计算,天然海泡石和酸化海泡石对三种重金属离子的吸附能力顺序为Cu>Pb>Cd。Cd2+和Cu2+在海泡石和酸化海泡石表面的吸附等温线符合Langmuir方程,Pb2+离子的吸附由于随溶液pH的升高而产生表面沉淀,导致其吸附等温线偏离Langmuir方程。该项研究可为海泡石在土壤重金属污染修复中的应用提供一定的理论基础。The surface characteristics of natural and acid-activated sepiolites were studied through surface acid-base reactions. The adsorption experiments of Pb2＋, Cd2＋ and Cu2＋ on natural and acid-activated sepiolites were performed and the adsorption mechanisms were investi- gated. The maximum adsorption capacities were 32.06 mg· g-1 pb2＋, 22.10 mg· g-1 Cu2＋, and 11.48 mg·g-1 Cd2＋ for natural sepiolite, and 35.28 mg· g-1 pb2＋, 24.36 mg· g-1 Cu2＋, and 13.62 mg·g-1 Cd2＋ for acid-activated sepiolite, respectively. The adsorption capabilities of natural and acid-activated sepiolites for Pb2＋, Cd2＋ and Cu2＋ calculated from the amount of substance were in the order： Cu2＋〉Pb2＋〉Cd2＋. Langmuir isotherm could describe the sorption data of Cu2＋ and Cd2＋ on natural and acid-activated sepiolites with a good fitness. The XRD patterns and IR spectra indicated that acid treatment made CaCO3 in natural sepiolite decomposed and increased the surface area. The pHzpc of acid-activated sepiolite decreased compared with the natural sepiolite, which suggested that acid treatment increased the surface acidity of sepiolite and the surface available sites for heavy metal adsorption. It could be concluded that isomorphous substitution and surface complexation coexist during the adsorption processes of Pb2＋, Cd2＋ and Cu2＋ onto natural and acid-activated sepiolites. Meanwhile surface precipitation could also occur for the adsorption of Pb2＋. on the natural and acid-activated sepiolites, especially in basic solutions.

关 键 词：海泡石 酸处理 重金属 吸附 

分 类 号：X53[环境科学与工程—环境工程]