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| Effect of silicon additives on the adsorption thermodynamics of cadmium in paddy soil with different pH levels |
| Received:February 28, 2017 |
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| KeyWord:silicon;cadmium;pH;paddy soil;adsorption thermodynamics |
| Author Name | Affiliation | E-mail | | ZHAO Yu-ting | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | WANG Yao-jing | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China
College of Science, Shenyang Agricultural University, Shenyang 110866, China | | | YING Bo | Liaoning Environmental Monitoring and Experiment Center, Shenyang 110161, China | | | YANG Dan | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | HE Na | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | | | LIU Ming-da | College of Land and Environment, Shenyang Agricultural University, Shenyang 110866, China | mdsausoil@163.com |
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| Abstract: |
| In previous studies, most silicon additives for soil were alkaline compounds that increased soil pH and introduced potential interfering ions. In this study, the effect of silicon on the adsorption thermodynamics of Cd in paddy soil with different pH levels was investigated through adsorption isotherm experiments. HNO3 was used to neutralize the alkalinity of Na2SiO3, while different concentrations of NO3- and Na+ between treatments were balanced with NaNO3. The results showed that Freundlich adsorption models could fit well to simulate the Cd adsorption characteristics at three different temperatures(25℃, 35℃, 45℃) in two types of soils. Cd adsorption was restricted in alkaline soil but enhanced in acidic soil at different temperatures after the addition of silicon. Thermodynamic parameters showed that the adsorption processes were endothermic and spontaneous, and entropy increased. At increased levels of silicon, △G increased and △H and △S decreased in alkaline soil, whereas △G decreased, and △H and △S increased in acidic soil.This phenomenon indicates that the spontaneity of Cd adsorption decreased in alkaline soil, but increased in acidic soil, with the addition of silicon. |
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