Hu Huimin, Zhang Qiwu, Wang Chao, Chen Min, Chen Mengfei
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China.
School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan 430070, China; Hubei Key Laboratory of Mineral Resources Processing and Environment, Wuhan University of Technology, Wuhan 430070, China.
J Hazard Mater. 2022 Feb 15;424(Pt D):127708. doi: 10.1016/j.jhazmat.2021.127708. Epub 2021 Nov 10.
Iron manganese oxide resources are widely derived from the geological structure, and their combinations play an important role in the migration and transformation of arsenic. Iron oxide and manganese oxide exist generally in a mixed state in Fe-Mn oxides synthesized via the well studied co-precipitation methods using potassium permanganate and manganese/iron sulfates. Herein, a newly designed Fe-Mn-O compositing oxide with Fe-MnO, Mn-FeO, (FeMn)OOH solid solution and FeOOH as the main components, simply through solvent-free mechanical ball milling pyrolusite (MnO) and ferrihydrite (FeOOH) together has been reported. Atomic-scale integrations by doping Fe and Mn with each other were detected and an adsorption-oxidation bifunctionality was achieved, where Fe-doped MnO served as oxidizer for As(III) and amorphous/ground FeOOH acted as adsorbent first for As(III) and then As(V) from the oxidization. The maximal adsorption for As(III) could reach 44.99 mg/g and over 82.5% of As(III) was converted to As(V). More importantly, high removal ability of arsenic worked in a wide pH range of 2-10.5%, and 87.2% of its initial adsorption-oxidation capacity could be kept even after 5-cycles reuse for treating 20 mg/L As(III) with a dosage at 1 g/L. Together with the enhanced adsorption capacity by the milled FeOOH, surface electron transfer efficiency of the developed Fe-MnO surrounded with Mn-FeO has been studied for the first time to understand the oxidization effect to As(V). Besides the environment-friendliness of ball milling method, the prepared sample is quite stable without noticeable metal release into solution. Mechanism studies of arsenic removal by the as-prepared Fe-Mn-O oxide provide a new direction for improving the oxidation efficiency of MnO to As(III) based on the widely available cheap Mn and Fe oxides, contributing to the development of advanced oxidization process in the treatment of waste water.
铁锰氧化物资源广泛源自地质结构，它们的组合在砷的迁移和转化中起着重要作用。在通过使用高锰酸钾和锰/铁硫酸盐的充分研究的共沉淀方法合成的铁锰氧化物中，氧化铁和氧化锰通常以混合状态存在。在此，报道了一种新设计的以Fe-MnO、Mn-FeO、(FeMn)OOH固溶体和FeOOH为主要成分的铁锰复合氧化物，它是通过将软锰矿(MnO)和水铁矿(FeOOH)在无溶剂条件下简单地机械球磨在一起而制备的。检测到通过相互掺杂铁和锰实现了原子尺度的整合，并实现了吸附-氧化双功能，其中铁掺杂的MnO用作As(III)的氧化剂，非晶态/研磨后的FeOOH首先作为As(III)的吸附剂，然后在氧化后作为As(V)的吸附剂。对As(III)的最大吸附量可达44.99 mg/g，超过82.5%的As(III)转化为As(V)。更重要的是，在2-10.5%的宽pH范围内对砷具有高去除能力，即使在以1 g/L的剂量处理20 mg/L As(III)进行5次循环再利用后，仍可保持其初始吸附-氧化能力的87.2%。连同研磨后的FeOOH提高的吸附容量，首次研究了被Mn-FeO包围的发达的Fe-MnO的表面电子转移效率，以了解对As(V)的氧化效果。除了球磨法的环境友好性外，制备的样品相当稳定，没有明显的金属释放到溶液中。所制备的铁锰氧化物去除砷的机理研究为基于广泛可用的廉价锰和铁氧化物提高MnO对As(III)的氧化效率提供了新方向，有助于废水处理中高级氧化工艺的发展。
