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Effects of two ionic liquids on Cd2+ adsorption on four soils
Received:January 01, 2016  
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KeyWord:Cd2+;2,3-Pyridinedicarboxylic acid;4,5-Imidazoledicarboxylic acid;soils;adsorption
Author NameAffiliationE-mail
XUAN Liang School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China 
 
WANG Yu-jun Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China yjwang@issas.ac.cn 
LIU Hai-long Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
ZHOU Dong-mei Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China  
SUN Qing-ye School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China sunqingye@ahu.edu.cn 
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Abstract:
      The effects of 2,3-Pyridinedicarboxylic acid and 4,5-Imidazoledicarboxylic acid on Cd2+ adsorption on four soils with different characteristics(Wujin, Wuxian, Nanjing and Yixing soils) were investigated. Results showed that the adsorption of Cd2+ on soils depended on the characteristics of soils. The presence of ionic liquids significantly affected the adsorption of Cd2+ on soils. Compared with the control, the presence of 1 mmol·L-1 2,3-Pyridinedicarboxylic acid reduced the maximum adsorption of Cd2+ on Wujin, Wuxian, Nanjing and Yixing soils by 209, 834, 667 and 509 mg·kg-1, respectively, whereas adding 1 mmol·L-1 4,5-Imidazoledicarboxylic acid decreased the maximum Cd2+ adsorption by 226, 54, 124 and 81 mg·kg-1 on Wujin, Wuxian, Nanjing, and Yixing soils, respectively. Therefore, 2,3-Pyridinedicarboxylic acid showed greater effects on Cd2+ adsorption on tested soils than 4,5-Imidazoledicarboxylic acid did. The free Cd2+ ions in the equilibrium solution measured by Cd ion selective electrode showed that both ionic liquids were able to complex with Cd2+, leading to decreased Cd2+ ion concentrations in soil solution, and consequently reduced Cd2+ adsorption on soils. The complexing capability of 2,3-Pyridinedicarboxylic was stronger than that of 4,5-Imidazoledicarboxylic acid, which resulted in greater inhibition of Cd2+ sorption on soils. Our results indicate that ionic liquids could decrease the adsorption of Cd2+ on soils, but increase the mobilization and environmental risk of soil Cd2+.