CADMIUM ADSORPTION MAXIMA OF SOILS AS MEASURED BY THE LANGMUIR ISOTHERM

Abstract

Thirty surface soils were equilibrated with four cadmium chloride solutions in a study of cadmium adsorption by soils. The data fitted the Langmuir isotherm. Where the amount adsorbed by the soil is x/m and the solution concentration at equilibrium is C, simple correlation coefficients, relating four pairs of [Formula: see text] and C for each soil, averaged 0.993. Adsorption maxima for all soils were similar in magnitude and correlated with aluminum and zinc soluble in 0.01 M CaCl2. The coefficients related to the bonding energy generally decreased in the order: organic > heavy clay > sandy and silt loam > sandy soils, and were correlated with total aluminum and iron. From a set of 13 soil properties, linear regression equations to predict the Langmuir parameters included only those variables that contributed significantly.