摘要
通过等温吸附试验,研究外源硅对两种不同pH水田土壤铅吸附热力学特征的影响。试验中采用硝酸中和硅酸钠的碱性,以硝酸钠补齐各处理间钠离子和硝酸根离子的差异,消除了因加入硅酸盐改变体系pH及伴随离子对土壤吸附铅可能产生的影响。结果表明:在本试验中,Freundlich方程能较好地描述3种温度下两种土壤对铅的吸附特征;加硅促进了酸性土壤对铅的吸附,抑制了碱性土壤对铅的吸附;根据热力学函数关系计算的△G<0、△H>0、△S>0,说明两土壤对铅的吸附是吸热、熵增的物理过程为主;加硅后,酸性土壤△G变小、△H变大、△S变大,碱性土壤△G变大、△H变小、△S变小,说明加硅使酸性土壤吸附铅的自发性提高、碱性土壤吸附铅的自发性降低。
The effect of added silicon on the adsorption and the thermodynamics of lead（Pb）in paddy soils with two different pH was investi- gated by the adsorption isotherm experiment. The HNO3 was used to neutralize the alkalinity of Na2SiO3, and the different concentration of NO3- and Na＋ between treatments were balanced with the addition of NaNO3, thus the effect of pH and accompanying ions by added silicate on Pb adsorption was eliminated. Results showed that Freundlich adsorption models could fit well to simulate the Pb adsorption characteristics at three different temperatures and in two types of soils. Added silicon enhanced Pb adsorption in acid soil, while added silicon decreased Pb adsorption in alkaline soil. The adsorption of Pb in the two types of soils was physically endothermic progress with increasing entropy as indi- cated by the results of thermodynamics function：△G〈0,△H〉0,△S〉0.After addition silicon, △G decreased,and △H and△S increased in acid soil, while in alkaline soil, △G increased, and △H and △S decreased, indicating that the spontaneity of Pb adsorption increased in acid soil but decreased in alkaline soil after addition of silicon.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2012年第9期1729-1733,共5页
Journal of Agro-Environment Science
基金
国家自然科学基金项目(41101290)
辽宁省自然科学基金项目(201102188)
辽宁省教育厅创新团队项目(2009T086)
关键词
硅
铅
水田土壤
吸附
热力学
silicon； lead； paddy field soil； adsorption； thermodynamics
