摘要
本文研究了三水铝石、针铁矿、高岭石、二氧化锰对Cr(Ⅵ)的吸附作用,结果表明:四种矿物对Cr(Ⅵ)吸附等温线符合Langmuir和Freundlich公式,吸附动力学曲线可以用Elovich公式、双常数速率公式和抛物线扩散公式来描述。溶液中离子强度的增加,四种矿物对Cr(Ⅵ)吸附量都有不同程度的减少。三种阴离子对Cr(Ⅵ)吸附量的影响为:H_2PO_4-和HPO_4^(2-)>SO_4^(2-)>>Cl-.二氧化锰对Cr(Ⅵ)的吸附量随pH升高而降低,高岭石、针铁矿和三水铝石对Cr(Ⅵ)吸附量在pH 6～7之间出现吸附最大值。
Cr (Ⅵ) adsorption on several minerals was studied. The results showed that: the amounts of Cr(Ⅵ)adsorbed by 4 minerals followed the sequence. gibbsite>geothite>manganese peroxide> Kaolinite. Their adsorption isotherms fit the Langmuir and Freundlich equations quite well. The kinetics curves of Cr (Ⅵ) adsorption might be described by the Elovich equation, Parabolic diffusion equation and Two-constant rate equation. As ionic strength of the solution increased, the amounts of Cr(Ⅵ)adsorption by 4 minerals decreased in different degree. The presence of SO4 2- HPO4 2- H2PQ4- in soil solution might greatly depress Cr (Ⅵ) adsorption. The depressing extent of these anions was found to follow the sequence..HPO42-,H2P04->SO42->>Cl-. The pH value of equilibrium solution was one of the factors affecting Cr (Ⅵ) adsorption. As the solution pH increased, the amounts of Cr (Ⅵ) adsorbed by manganese peroxide decreased. The maximum Cr (Ⅵ) adsorption on kaolinite, geothite and gibbsite appeared in the range of pH 6-7. The mechanism of Cr (Ⅵ) adsorption on the minerals seems to be similar to that of phosphate.
基金
国家自然科学基金
关键词
土壤
化学行为
矿物
铬
吸附作用
sgibbsite
geothite
kaolinite
chromium
adsorption
