Xing Bobo, Graham Nigel, Yu Wenzheng
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 10086, Beijing, China.
Department of Civil and Environmental Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK.
Commun Chem. 2020 Mar 25;3(1):38. doi: 10.1038/s42004-020-0284-3.
Humic acid (HA) is particularly important in iron-bearing mineral transformations and erosion at the water-mineral boundary zone of the Earth. In this study, three stages of the possible pathway by which HA causes mineral transformation from siderite to goethite are identified. Firstly, a Fe(II)-HA complex is formed by chelation, which accelerates the dissolution and oxidation of Fe(II) from the surface of siderite. As the Fe(II)-HA complex retains Fe atoms in close proximity of each other, ferrihydrite is formed by the agglomeration and crystallization. Finally, the ferrihydrite structurally rearranges upon attachment to the surface of goethite crystals and merges with its structure. The influence of low concentrations of HA (0-2 mg/L) on phosphate adsorption is found to be beneficial by the inducing of new mineral phases. We believe that these results provide a greater understanding of the impact of HA in the biogeochemical cycle of phosphate, mineral transformation.
腐殖酸（HA）在地球水-矿物边界带含铁矿物的转化和侵蚀过程中尤为重要。在本研究中，确定了HA导致菱铁矿向针铁矿矿物转化的可能途径的三个阶段。首先，通过螯合形成Fe（II）-HA络合物，这加速了菱铁矿表面Fe（II）的溶解和氧化。由于Fe（II）-HA络合物使Fe原子彼此紧密相邻，通过团聚和结晶形成了水铁矿。最后，水铁矿在附着到针铁矿晶体表面时发生结构重排并与其结构合并。发现低浓度HA（0-2mg/L）对磷酸盐吸附的影响通过诱导新矿物相而有益。我们认为这些结果有助于更深入地了解HA在磷酸盐生物地球化学循环、矿物转化中的影响。
