磁铁矿
吸附
化学
机制(生物学)
腐植酸
还原(数学)
无机化学
反应机理
组合化学
化学工程
催化作用
有机化学
材料科学
冶金
肥料
哲学
几何学
数学
认识论
工程类
作者
Jingjie Chang,Jia Zhang,Hui Wang,Yunfei Bai,Yu Liu,Yanze Bi,Huanzhen Zhang,Honghan Chen,Samuel Barnie,Haijiao Xie
标识
DOI:10.1016/j.cej.2022.138648
摘要
• Antagonistic adsorption and synergistic reduction of Cr(VI) were observed in MHAs. • A two-site model of the MHAs surface, named site A and site B, was proposed. • HA was only present at site A, where only the reduction of Cr(VI) by HA occurred. • Site B was bare Mag without any HA, where only Mag could adsorb and reduce Cr(VI). • A quantitative multi-step kinetic model was successfully established. Ubiquitous Fe-OM complexes in subsurface environments have substantial retention effects on Cr(VI) migration; however, whether these effects follow the superposition principle remains unclear, particularly for Fe(II)-containing minerals. In this study, Cr(VI) adsorption and reduction by magnetite-humic acid (HA) adsorption complexes (MHAs) were investigated under mildly acidic conditions, and MHAs were found to have antagonistic adsorption and synergistic reduction effects on Cr(VI). Based on the Raman mapping characterization, the MHAs surface was extremely heterogeneous, consisting of two types of sites: (A) magnetite covered by HA and (B) bare magnetite without HA. Owing to the coverage of the magnetite surface by HA, the adsorption and reduction by magnetite was depressed with an antagonistic efficiency of 8%–70%, varying with the amount of adsorbed HA. In contrast, the synergistic reduction of Cr(VI) by the HA component at site (A) was observed, resulting in a synergistic factor of up to 44, which could be attributed to the molecular fractionation and functionality activation of HA on the magnetite surface according to the fluorescence excitation-emission matrix combined with parallel factor analysis and density functional theory calculations. Accordingly, a multi-step kinetic model of Cr(VI) adsorption and reduction by MHAs based on antagonistic and synergistic effects was established to quantitatively simulate the Cr(VI) interfacial behavior ( R >0.9). This study is instructive for accurately assessing the effect of Fe-organic matter complexes on Cr(VI) migration and benefits the development of remediation materials for Cr(VI)-contaminated soils and groundwater.
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