长三角地区4种典型土壤对Zn吸附-解吸的特性

Adsorption-desorption behavior of zinc in four kinds of Yangtze River delta soil

选择长三角地区具有代表性的4种土壤,采用不同浓度的外源Zn溶液进行吸附,用模拟雨水作为解吸剂,研究4种土壤对Zn的吸附-解吸特性,以及Zn的连续解吸特性.结果表明:4种土壤对Zn的吸附量均随吸附平衡浓度的增大而增加,且吸附量与土壤的pH正相关;吸附等温线可以用Freund lich方程和Temkin方程来描述.由Langmu ir方程求得的4种土壤的最大吸附量的大小顺序为:q(青紫泥)>q(滩潮土)>q(乌黄土)>q(黄泥沙田).最大缓冲容量的顺序为:MBC(滩潮土)>MBC(乌黄土)>MBC(青紫泥)>MBC(黄泥沙田).4种土壤对Zn的解吸量均随着解吸平衡浓度的增大而线性增加.连续解吸可提高土壤对Zn的解吸率,但连续解吸数次后,解吸过程趋于稳定.

The soil for the experiments was four kinds of typical soil in Yangtze River delta. The soil with different concentration zinc adsorbed was desorbed by simulated rain. The result of adsorption-desorption revealed that adsorption of zinc was enhanced with the concentration of zinc and has the positive relation to pH. The adsorption isotherm could be described by Freundlich and Temkin equation. The limit adsorption computed by Langmuir equation had the following order ： q （purple mud） 〉 q （ bottomland soil） 〉 q （ yellow soil） 〉 q （ yellow mud sand）. The MBC follows the order： MBC （ bottomland soil） 〉 MBC （ yellow soil ） 〉 MBC （ purple mud ） 〉 MBC （ yellow mud sand）. The desorption of four kinds of soil raised with the desorptive equilibrium concentration. Continual desorption makes a higher desorption ratio, and after several times of desorption, the process of desorption tend to be stable.