Application of the NICA-Donnan model for proton, copper and uranyl binding to humic acid
Application of the NICA-Donnan model for proton, copper and uranyl binding to humic acid
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DOI：
10.1524/ract.92.9.567.54984
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发表时间：
2004
影响因子：
1.8
通讯作者：
Takumi Saito;S. Nagasaki;Satoru Tanaka;L. Koopal
中科院分区：
文献类型：
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作者：
Takumi Saito;S. Nagasaki;Satoru Tanaka;L. Koopal
摘要腐植酸是一种天然有机物质，在水体和土壤系统中重金属和锕系元素离子的迁移中起着重要作用。在本研究中，质子，铜离子和铀酰离子的纯化奥德里奇腐殖酸（PAHA）的结合进行了研究，并与非理想竞争吸附（NICA）模型扩展静电相互作用根据Donnan模型（NICA-Donnan模型）的结果进行了建模。该模型的NICA部分使人们能够描述的竞争性离子结合到异质衬底考虑到每个离子的不同化学计量。NICA-Donnan模型可以描述在大浓度范围内（3<pH<11; 3<pCu<13; 4<pUO 2 <18）和在宽范围的环境条件（pH、离子强度）下离子与PAHA的结合。根据模型描述，PAHA的亲和力分布是双峰的，具有大约相等数量的“羧基”-（低logKH）和“酚类”-型（高logKH）位点。铜和铀酰的结合反应的化学计量参数表明单和双齿结合。一些特别注意的是支付的“羧基”和“酚”型网站的绑定铀酰离子的分布。这样的信息对于与关于结合的光谱信息进行比较是有用的。
Summary Humic acids are natural organic materials that play an important role in the migration of heavy metal and actinide ions in aquatic and soil systems. In the present study, the binding of protons, copper ions and uranyl ions to the purified Aldrich humic acid (PAHA) is investigated and the results are modeled with the Non-Ideal Competitive Adsorption (NICA) model extended with electrostatic interactions according to the Donnan model (NICA-Donnan model). The NICA part of the model enables one to describe the competitive ion binding to a heterogeneous substrate taking into account a different stoichiometry per ion. The NICA-Donnan model can describe the binding of the ions to PAHA in large concentration ranges (3<pH<11; 3<pCu<13; 4<pUO2<18) and over a wide range of environmental conditions (pH, ionic strength). From the model description it follows that the affinity distribution of PAHA is bimodal with about equal numbers of "carboxylic"- (low logKH) and "phenolic"-type (high log KH) sites. The stoichiometry parameters of the binding reactions for copper and uranyl indicate both mono- and bi-dentate binding. Some specific attention is paid to the distribution of the bound uranyl ions over the "carboxylic" and "phenolic"-type sites. Such information is useful for comparison with spectroscopic information on the binding.