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359923 
Journal Article 
Effects of organic acids on Cd2+ and Pb2+ adsorption on goethite and bentonite at different pH 
Huang, L; Liu, C; Hu, H; Liu, F; Li, X 
2007 
44 
4 
643-649 
The effects of organic acids (acetic acid, tartaric acid and citric acid) on Cd2+ and Pb2+ adsorption on goethite and bentonite were studied with the batch method. Results show that pH decreased with the increase in concentration of Cd2+ and Pb2+ in the goethite and bentonite isothermal systems when the concentration of Cd2+ and Pb2+ was lower than 0.2 mmol L-1 and 4.0 mmol L-1, respectively. The decrease of pH in bentonite system was more obvious than in goethite system. The effect of pH on Cd2+ and Pb2+ adsorption of goethite and bentonite varied sharply with organic acids added. Cd2+ sorption rate was small with goethite when pH was in the range from 3 to 4.5, but it went upward sharply when pH was higher (4.5 < pH < 8), and tended toward saturation at pH 8. Pb2+ sorption rate began to increase when pH was 3 with goethite, and it leveled off to 95% at pH 5.5. Affected by three organic acids, Cd2+ sorption rate increased slowly from 40% at pH 3 with bentonite, and approached close to 90% at pH 8. Pb2+ sorption rates were around 60% in bentonite systems added with different organic acid. They increased to 80% when citric acid was added and 95% when other organic acid added. Cd2+ and Pb2+ sorption rates varied from 40 to 90% with bentonite at different pH, but from 3 to 90% with goethite. In terms of effect of organic acids on Cd2+ and Ph2+ adsorption of goethite, the three acids were in the order of citric acid > tartaric acid > acetic acid, but the effect was not clear with bentonite. 
acetic acid; adsorption; bentonite; cadmium; citric acid; clay minerals; goethite; lead; soil pH; tartaric acid; limonite; Soil Chemistry and Mineralogy (JJ200)