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Effects of organic acids on Cd adsorption and desorption by two anthropic soils

查看全文 作　　者：Jingui [1,2]WANG Jialong [1,2]LV Yaolong [1,2]FU 高影响力作者 机构地区：[1]College of Resources and Environment, Northwest A&F University, Yangling 712100, China;[2]Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling 712100, China高影响力机构 出　　处：《Frontiers of Environmental Science & Engineering》索引2013年第7卷第1期,共12页高影响力期刊 摘　　要：The objective of this experiment was to study the effects of malic, tartaric, oxalic, and citric acid on the adsorption and desorption characteristics of Cd by two typical anthropic soils (lou soil and irrigation-silted soil) in North-west China. Cadmium adsorption and desorption were studied under a range of temperatures (25℃, 30℃, 35℃, 40℃), organic acid concentrations (0.5-5.0 mmol·L-1), and pH values (2-8). The results showed that the Cd adsorption capacity of the lou soil was significantly greater than that of the irrigation-silted soil. Generally, Cd adsorption increased as the temperature increased. In the presence of NaNO3, the adsorption of Cd was endothermic with △H values of 31.365 kJ·mo1-1 for lou soil and 28.278 kJ·mol-1 for irrigation-silted soil. The endothermic reaction indicated that H bonds were the main driving force for Cd adsorption in both soils. However, different concentrations of organic acids showed various influences on the two soils. In the presence of citric acid, chemical adsorption and van der Waals interactions were the main driving forces for Cd adsorption rather than H bonds. Although the types of organic acids and soil properties were different, the effects of the organic acids on the adsorption and desorption of Cd were similar in the two soils. The adsorption percentage of Cd generally decreased as organic acid concentrations increased. In contrast, the adsorption percentage increased as the pH of the initial solution increased. The exception was that adsorption percentage of Cd increased slightly as oxalic acid concentrations increased. In contrast, the desorption percentage of Cd increased with increasing concentrations of organic acids but decreased as the initial solution pH increased. 关 键 词：ADSORPTION DESORPTION CADMIUM organicacids TEMPERATURE anthropic SOIL
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