Faculty of Natural Sciences, Hung Vuong University, Nguyen Tat Thanh Street, Viet Tri, Phu Tho, 35120, Vietnam.
Angewandte Geologie, Universität Göttingen, Goldschmidtstraße 3, 37077, Göttingen, Germany.
Sci Rep. 2021 May 7;11(1):9814. doi: 10.1038/s41598-021-89318-w.
The role of manganese dioxide (MnO) in the process of water treatment using metallic iron (Fe/HO) was investigated in quiescent batch experiments for t ≤ 60 d. MnO was used as an agent to control the availability of solid iron corrosion products (FeCPs) while methylene blue (MB) was an indicator of reactivity. The investigated systems were: (1) Fe, (2) MnO, (3) sand, (4) Fe/sand, (5) Fe/MnO, and (6) Fe/sand/MnO. The experiments were performed in test tubes each containing 22.0 mL of MB (10 mg L) and the solid aggregates. The initial pH value was 8.2. Each system was characterized for the final concentration of H, Fe, and MB. Results show no detectable level of dissolved iron after 47 days. Final pH values varied from 7.4 to 9.8. The MB discoloration efficiency varies from 40 to 80% as the MnO loading increases from 2.3 to 45 g L. MB discoloration is only quantitative when the operational fixation capacity of MnO for Fe was exhausted. This corresponds to the event where adsorption and co-precipitation with FeCPs is intensive. Adsorption and co-precipitation are thus the fundamental mechanisms of decontamination in Fe/HO systems. Hybrid Fe/MnO systems are potential candidates for the design of more sustainable Fe filters.
在静置批量实验中研究了二氧化锰（MnO）在使用金属铁（Fe/HO）进行水处理过程中的作用，实验时间为 t ≤ 60 天。MnO 被用作控制固体铁腐蚀产物（FeCPs）可用性的试剂，而亚甲基蓝（MB）是反应性的指示剂。研究的系统有：（1）Fe，（2）MnO，（3）砂，（4）Fe/砂，（5）Fe/MnO，和（6）Fe/砂/MnO。实验在每个含有 22.0 毫升 MB（10 毫克/升）和固体聚集体的试管中进行。初始 pH 值为 8.2。每个系统都对 H、Fe 和 MB 的最终浓度进行了表征。结果表明，47 天后没有检测到溶解铁的水平。最终 pH 值从 7.4 到 9.8 不等。当 MnO 负载量从 2.3 克/升增加到 45 克/升时，MB 的褪色效率从 40%变化到 80%。只有当 MnO 对 Fe 的操作固定容量耗尽时，MB 褪色才是定量的。这对应于吸附和与 FeCPs 共沉淀变得剧烈的事件。因此，吸附和共沉淀是 Fe/HO 系统中去污的基本机制。混合 Fe/MnO 系统是设计更可持续的 Fe 过滤器的潜在候选者。
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