恒电荷土壤及可变电荷土壤与离子间相互作用的研究ⅢCu^(2+)和Zn^(2+)的吸附特征  

INTERACTION OF IONS WITH CONSTANT CHARGE SOILS AND VARIABLE CHARGE SOILS Ⅲ. CHARACTERISTICS OF Cu^(2+) AND Zn^(2+) ADSORPTION IN SINGLE AND CO-EXISTING SYSTEMS

作　　者：徐明岗[1] 季国亮[1] 

机构地区：[1]中国科学院南京土壤研究所,南京210008

出　　处：《土壤学报》2005年第2期225-231,共7页Acta Pedologica Sinica

基　　金：国家自然科学基金项目 (4 983 10 0 5 );国家重点基础研究发展规划项目 (973课题 2 0 0 2CB410 80 9)资助

摘　　要：研究了3种典型可变电荷土壤和4种典型恒电荷土壤在不同pH和不同浓度下单纯及共存体系中Cu2 + 和Zn2 + 的吸附及其影响因素。结果表明,两类土壤对Cu2 + 或Zn2 + 的吸附量均随平衡浓度增加而增大,符合Langmuir吸附等温式;当Cu2 + 、Zn2 + 浓度一定时,pH升高使Cu2 + 、Zn2 + 吸附量增大,但当pH >5时,Cu2 + 、Zn2 + 吸附量随pH变化甚微,出现一个接近最大吸附量的“平台”。当添加Cu2 + 、Zn2 + 浓度相同,但二种离子的总浓度不同时,平衡液的Cu2 + /Zn2 + 浓度比均小于1,说明两类土壤对Cu2 + 的吸附选择性大于Zn2 + ,且这种趋势不因pH和离子浓度而改变。当Cu2 + 、Zn2 + 共存时,使可变电荷土壤的Zn2 + 吸附量减小约70 % ,是恒电荷土壤降低量的约1.5倍;可变电荷土壤吸附一个Cu2 + 或Zn2 + 时所释放H+ 的平均数,明显大于恒电荷土壤者,说明可变电荷土壤对Cu2 + 及Zn2 +Adsorptions of Cu 2+ and Zn 2+ by three typical variable charge soils and four typical constant charge soils different in pH and in accompanying ion, Na +, Zn 2+ or Cu 2+ were determined, respectively. The results showed that adsorption of Cu 2+ and Zn 2+ by the soils could be described by the Langmiur equation C/(X m)=1/Kb+C/b both in the single ion and co existing ions systems. The adsorption of Cu 2+ or Zn 2+ increased with pH and reached a plateau value when the pH value was 5. The affinity in adsorption of Cu 2+ was greater than that of Zn 2+ . The mechanism of adsorption Cu 2+ and Zn 2+ was closely related to chemical composition and surface properties of the soils. The relative contribution of specific adsorption to the adsorption of Cu 2+ and Zn 2+ by the variable charge soils was greater than that by the constant charge soils.

关 键 词：恒电荷土壤 可变电荷土壤 ZN^2+ CU^2+ 浓度 吸附特征 添加 吸附量 吸附等温式 吸附选择性 

分 类 号：S153[农业科学—土壤学] X172[农业科学—农业基础科学]