Abstract Manganese oxides are ubiquitous in soils and sediments, and their formation and transformation processes affect the migration and transformation of heavy metals and organic pollutants. Most previous work has been focused the oxidation of Mn(II) on Mn(IV) oxide surface, but it remains poorly understood how Mn(II) interacts with manganite under oxic conditions. Here, the interactions between manganite and dissolved Mn(II) within pH 5.0–9.0 under oxic conditions were systematically studied. The results indicated that adsorbed Mn(II) was directly oxidized to manganite on the surface, and the oxidation rate increased with increasing pH and oxygen partial pressure. Electrons are likely transferred in bulk manganite during the oxidation process of Mn(II). Although manganite induced Mn(II) oxidation and the epitaxial growth of bulk particles, there was no obvious change in mineral phase. Dissolved oxygen accelerated the growth of manganite in Mn(II) solution. Compared with the absence of manganite, the presence of manganite inhibited the formation of hausmannite from Mn(II) oxidation by oxygen in air. This study reveals the catalytic oxidation process and mechanism of Mn(II) on manganite surface, and improves the understanding of manganite crystal growth in supergene environments.

中文翻译：

---

氧化条件下锰矿上Mn(II)多相催化氧化的外延生长机理

摘要 锰氧化物普遍存在于土壤和沉积物中，其形成和转化过程影响重金属和有机污染物的迁移转化。以前的大多数工作都集中在 Mn(II) 在 Mn(IV) 氧化物表面上的氧化，但人们对 Mn(II) 如何在有氧条件下与锰酸盐相互作用仍知之甚少。在这里，系统研究了在有氧条件下，在 pH 5.0-9.0 范围内锰矿与溶解的 Mn(II) 之间的相互作用。结果表明吸附的Mn(II)在表面被直接氧化为锰矿，氧化速率随着pH值和氧分压的增加而增加。在 Mn(II) 的氧化过程中，电子可能会转移到块状锰矿中。尽管锰矿诱导了 Mn(II) 氧化和大块颗粒的外延生长，矿物相无明显变化。溶解氧加速了锰矿在 Mn(II) 溶液中的生长。与没有锰铁矿相比，锰铁矿的存在抑制了空气中氧气氧化锰（II）而形成的锰铁矿。本研究揭示了锰矿表面Mn(II)的催化氧化过程和机理，提高了对表生环境中锰矿晶体生长的理解。