Effects of pH,Ionic Strength and Dielectric Constant on Adsorption of Low Molecular Weight Organic Acids in Variable Charge Soil
pH、离子强度和介电常数对低分子量有机酸在红壤中吸附行为的影响

The effects of pH, ionic strength and dielectric constant on adsorption of low molecular weight organic acids in a variable charge soil were investigated by a batch equilibrium method. The results indicated that the adsorption amount of organic acids declined with the increase of solution pH. And the adsorption amount of oxalic and tartaric acids declined sharply with pH increasing from 3.5 to 5.0 and then decreased slowly (pH 5.0 ~ 7.0). When the initial concentrations of organic acids ranged from 1 to 2 mmol/L, the ionic strength had little influence on the adsorption of organic acids, but increased significantly with an increase of ionic strength when the initial concentrations ranged from 2 to 20 mmol/L. In addition, the adsorption amount of organic acids increased with a decrease of dielectric constant of the solvent. When 6% ethyl alcohol was contained in the solvent, the adsorption amount of oxalic, citric, tartaric and malic acids were 1.05, 1.05, 1.11 and 1.31 times respectively of those in the absence of ethyl alcohol.