土壤和粘粒矿物对亚硒酸盐的吸附和解吸

本文研究了三种土壤(砖红壤、红壤和黄棕壤)、高岭土和两种合成氧化铁(无定形氧化铁和针铁矿)对亚硒酸盐的吸附和解吸作用。讨论了亚硒酸盐的吸附特征,以及土壤中氧化铁对亚硒酸盐吸附和解吸的影响,根据实验资料与吸附等温方程式的拟合情况,作者认为以Freundlich和Langmuir公式为宜。此外,供试样品对亚硒酸盐的吸附和解吸结果表明,Se的吸附量随Se的添加量的增加而增加,但由于矿物组成各异,吸附量的差异显著。其吸附量的大小顺序为:无定形氧化铁>针铁矿>砖红壤>红壤>黄棕壤>高岭土;而被吸附Se的解吸能力则是高岭土>黄棕壤>红壤>砖红壤>针铁矿>无定形氧化铁。实验结果还表明,在各种矿物组成中,亚硒酸盐的吸附和解吸受氧化铁的影响很明显,三个土壤样品的吸附等温线都表现出氧化铁在初始阶段对亚硒酸盐吸附快而强烈的特征,而在去除氧化铁以后,这一特征也随之消失,硒的吸附量显著降低,而解吸率则明显上升。

ADSORPTION AND DESORPTION OF SELENITE BY SOME SOILS AND CLAY MINERALS

The adsorption and desorption of Se by three soils (latosol, red earth and yellow brown earth), kaolin and two synthetic iron oxides (amorphous iron oxids and goethite) are discussed in the present paper. On the basis of characteristics of adsorption isotherms, Freundlich equation and Lanynuir equation(C/Y=K/M+1/M·C)fit best for experimental data of samples used. The results obtained show that clay minerals play an important role in the adsorption and desorption of selenite. The amount or Se adsorbed in the samples increased with the amount of Se added, but the amounts of Se adsorbed varied greatly with the mineral composition of samples. The amounts of Se adsorbed vuere in the order: amorphous iron oxide > goethite > latosol > red earth > yellow brovvn earth > kaolin, but the desorption power was in the order: kaolin > yellow brown earth > red earth > latosol > goethite > amorpiious iron oxide.