化学
腐植酸
齿合度
吸附
酰胺
无机化学
有机化学
金属
肥料
作者
Wanpeng Chen,Xiaoliu Huangfu,Jingang Xiong,Hongxia Liu,Qiang He
标识
DOI:10.1016/j.watres.2023.120053
摘要
Widely distributed soil humic acid (HA) would significantly affect the environmental migration behavior of Tl(I), but a quantitative and mechanistic understanding of the dynamic Tl(I) retention process on HA is limited. A unified kinetic model was established by coupling the humic ion-binding model with a stirred-flow kinetic model, which quantified the complexation constants and responsiveness coefficients during dynamic Tl(I)-HA complexation. Furthermore, the heterogeneous complexation mechanism of HA and Tl(I) was revealed by batch adsorption experiments, stirred-flow migration experiments, and 2D-FTIR-COS analysis. An increase in pH significantly improved the responsiveness of HA organic binding sites, promoting Tl(I) dynamic retention. Monodentate carboxyl groups induced rapid Tl(I) complexation (kd = 1.9 min−1) in strongly acidic environments. Under weakly acidic conditions, Tl(I) retention on HA was mainly attributed to the synergistic complexation effect of carboxyl and amide groups. Among the groups, multidentate carboxyl-phenolic hydroxyl sites could achieve sustained Tl(I) retention due to their stable complexing properties (logK = 4.48∼7.46) and slow response (kd = 1.1 × 10−3 min−1). These findings are crucial for a comprehensive understanding of the environmental interactions of Tl(I) with humic substances in swamp environments.
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