The effects of manganese (Mn) mineral mixtures on arsenite (As(III)) removal (i.e., the sum of As(III) oxidation to As(V) and As species adsorption) were systematically quantified for the first time using varying ratios of hausmannite and manganite, common Mn(III)-containing oxides that often exist as mixtures in natural environments. Due to smaller particle sizes and a higher surface area, hausmannite alone exhibited a total As(III) removal of 8.86 μM m⁻² at pH 5, almost double that of manganite, 4.63 μM m⁻², with initially fast but then subsequently slower As(III) oxidation and Mn(II) production rates. Both minerals showed a substantial decrease in As(III) removal as pH increased. High resolution transmission electron microscopy (HRTEM) analysis showed mineral edge sites initially and preferably consumed for As(III) oxidation. Mixtures of hausmannite and manganite resulted in enhanced As(III) removal (9.62–11.2 μM m⁻²) relative to the single minerals at pH 5, increasing with increasing manganite quantities. The mineral mixtures also displayed two reaction phases, where As(III) oxidation and Mn(II) production were initially fast but then slowed after the first hour. Further, the mineral mixtures produced a Mn(II):As(V) ratio higher than the theoretical two, indicating enhanced mineral dissolution than that of a single Mn oxide. Enhanced reactivity was attributed to the aggregation structure of mixtures, as the presence of manganite effectively limited the aggregation of hausmannite particles, as observed in HRTEM, promoting the exposure of highly active edge sites for the surface-mediated reactions. Thus, mineral mixtures may serve as a better surrogate than a single mineral to examine the extent and magnitude of As(III) removal in natural environments, by more closely reflecting the heterogeneity and complexity in surface interactions and aggregation structures between the minerals.

首次系统地使用不同比率的锰对锰（Mn）矿物混合物对砷（As（III））去除（即，As（III）氧化成As（V）和As物种吸附的总和）的影响进行了量化。菱锰矿和锰矿，是常见的含Mn（III）的氧化物，通常在自然环境中以混合物的形式存在。由于更小的颗粒尺寸和较高的表面积，黑锰矿单独表现出总的As（III）的去除8.86的 μ M M ^-2在pH 5，几乎两倍锰酸，4.63  μ M M ^-2，最初具有快速但随后较慢的As（III）氧化和Mn（II）生成速率。随着pH值的升高，两种矿物均显示出As（III）去除量的显着降低。高分辨率透射电子显微镜（HRTEM）分析显示，最初存在矿物边缘位点，最好用于As（III）氧化。黑锰矿和锰的混合物导致增强的As（III）的去除（9.62-11.2  μ M M ^-2）相对于pH为5的单一矿物随锰矿量的增加而增加。矿物混合物还显示出两个反应阶段，其中As（III）氧化和Mn（II）生成最初较快，但在第一个小时后却减慢了速度。此外，矿物混合物产生的Mn（II）：As（V）之比高于理论值两者，表明矿物溶解度比单一Mn氧化物高。反应性的提高归因于混合物的聚集结构，因为在HRTEM中观察到，锰矿的存在有效地限制了菱锰矿颗粒的聚集，从而促进了高活性边缘位点的暴露，从而促进了表面介导的反应。因此，在自然环境中，矿物混合物可能比单一矿物更好地替代了矿物（以检测As（III）的去除程度和程度），