Irreversible characteristic of lead (Ⅱ) adsorption-desorption on soil clays
2007
Yang Yati | Zhang Yiping
chinois. 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K d与吸附常数K a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 Kaint与解吸常数log Kdint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。
Afficher plus [+] Moins [-]anglais. 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/Ka of soil clays showed the feature of NaNO3oxalic acidcitric acid at a constant pH, the irreversible degree showed the same sequence. So, concerning pH, the ratio of log Kdint/log Kdint (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.
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