Premium
ADSORPTION OF LEAD, COPPER, ZINC, COBALT, AND CADMIUM BY SOILS THAT DIFFER IN CATION‐EXCHANGE MATERIALS
Author(s) -
ABDELFATTAH ALY,
WADA KOJI
Publication year - 1981
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1981.tb01706.x
Subject(s) - chemistry , adsorption , allophane , selectivity , inorganic chemistry , halloysite , cadmium , ion exchange , montmorillonite , zinc , copper , selective adsorption , partition coefficient , metal , metal ions in aqueous solution , kaolinite , nuclear chemistry , mineralogy , ion , organic chemistry , catalysis , materials science , composite material
Summary The adsorption of Zn 2+ , Pb 2+ , Cu 2+ , Co 2+ , and Cd 2+ (M 2+ ) by soils was measured at concentrations ranging from 10‐ 7 to 10‐ 2 M in 10‐ 3 to 10‐ 2 M CaCI 2 . Exchange between Ca 2+ and M 2+ , and solubility products [M 2+ ][OH − ] 2 indicate that M 2+ is not precipitated as hydroxide but is adsorbed on cation‐exchange sites. The proportion of selective adsorption sites with specified values of the selectivity coefficient calculated using Ca as reference ion, increased in the order montmorillonite < humus, kaolinite, < allophane. imogolite < halloysite, iron oxides. Raising the soil pH by Ca‐saturation increased both the amount and affinity of adsorption. Selectivity of adsorption increased in the order Mg, Ca < Cd, Co < Zn < Cu, Pb, and the selectivity coefficient varied from < 1 to > 10 000. The formation of the coordination complexes of heavy metal with deprotonoted OH and COOH groups as ligands is suggested as a possible mechanism of selective adsorption.