| 摘要: |
| 为了探讨土壤粘粒表面Pb2+吸附-解吸的不可逆性特征，采用一次平衡法研究了陕西4种土壤粘粒对Pb2+的吸附和解吸特征。结果表明，在恒定pH条件下，残留吸附常数Kd与吸附常数Ka的比值称为吸附-解吸的不可逆性特征参数，Kd/Ka=1，表示吸附-解吸过程是可逆的；Kd/Ka≠1,表示该过程不可逆；在不同解吸溶液中，供试土壤粘粒表面Pb2+Kd/Ka值由大到小依次表现为NaNO3、草酸、柠檬酸，不可逆程度大小与此相同。在不同pH条件下，供试土壤粘粒表面Pb2+络合常数log Kinta与解吸常数logKintd的比值也可作为过程不可逆性特征参数；在不同介质中，其绝对值由大到小依次为NaNO3、柠檬酸、草酸，不可逆程度大小与此相反。 |
| 关键词: 土壤粘粒 Pb2+ 吸附-解吸 不可逆 |
| DOI： |
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| 基金项目:西北农林科技大学重点专项基金项目 |
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| Irreversible characteristic of lead (Ⅱ) adsorption-desorption on soil clays |
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| Abstract: |
| In order to investigate the irreversibility of the adsorption and desorption of Pb2+ on soil clays,one equilibrium method was used to study the characteristics of the adsorption and desorption of Pb2+ on soil clays in Shaanxi.The results were that the ratio of residual adsorption constant Kd to adsorption constant Ka was defined as the irreversible parameter of adsorption-desorption for Pb2+ on the soil clay.If Kd/Ka=1,the process of adsorption and desorption was reversible.If Kd/Ka≠1,the process of adsorption and desorption was irreversible.The ratio Kd of soil clays showed the feature of NaNO3>oxalic acid>citric acid at a constant pH,the irreversible degree showed the same sequence.So,concerning pH,the ratio of logKintd/logKinta(the intrinsic desorption constant/surface intrinsic complexation constant) Pb2+ on soil clays was defined as the parameter of irreversible,the ratio showed NaNO3>citric acid> oxalic acid in different mediums,the irreversible degree was just the opposite. |
| Key words: soil clay Pb2+ adsorption-desorption irreversible |
