在这项研究中,我们提出了一种适度的氧化策略,用于使用亚硫酸盐(S(IV))加速零价铁(ZVI)的氧化溶解,从而改善As(V)和As(III)的去除。结果显示,在存在2.0mMS(IV)的情况下,在pH03.0-7.0时,As(V)和As(III)都选择性地转化为sororodite,而在pH08.0-10.0时施加了As(III)氧化和As(V)固定作用。批量实验,自由基猝灭实验,和电子自旋共振(ESR)测量表明,ZVI最初增强了S(IV)激活以产生SO4·-,•OH,和质子,反过来,ZVI被这些自由基比被氧更强烈地进一步氧化。同时,由ZVI氧化产生的S(IV)氧化中和的羟基衍生的大量质子,保持酸性环境有利于生成的scorostite而不是铁(hydr)氧化物。X射线衍射(XRD)拉曼,衰减全反射-傅里叶变换红外(ATR-FTIR),X射线光电子能谱(XPS),X射线吸收精细结构(XAFS),场发射扫描电子显微镜(FESEM),和高分辨率透射电子显微镜(HRTEM)证实,sororodite是原位形成的,然后从ZVI表面剥落,大约75%的ZVI仍然可以被回收,这有助于在连续运行中高效地去除As和实际的As污染废水。S(IV)的应用实现了ZVI反应性改善之间的平衡,As(V)/As(III)移除,和原材料消耗,使其成为解决废水处理中砷污染的有前途的方法。
In this study, we proposed a moderate oxidation strategy for accelerating the oxidative dissolution of zerovalent iron (ZVI) using sulfite (S(IV)), thereby improving the removal of As(V) and As(III). Results revealed that, in the presence of 2.0 mM S(IV), both As(V) and As(III) were selectively converted into scorodite at pH0 3.0-7.0, while As(III) oxidation and As(V) immobilization were impressed over pH0 8.0-10.0. Batch experiments, radical quenching experiments, and electron spin resonance (ESR) measurements demonstrated that ZVI initially boosted S(IV) activation to generate SO4•-, •OH, and protons, and in turn, ZVI was further oxidized more intensely by these radicals than by oxygen. Concurrently, substantial protons derived from S(IV) oxidation neutralized hydroxyls produced by ZVI oxidation, maintaining an acidic environment conducive to the generation of scorodite rather than iron (hydr)oxides. Characterizations of X-ray diffraction (XRD), Raman, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), field emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) confirmed that scorodite was formed in situ and then exfoliated from the surface of ZVI, and approximately 75% of ZVI could still be recovered, which contributed to efficient As removal in successive runs and real As-polluted wastewater. The application of S(IV) achieved a balance among ZVI reactivity improvement, As(V)/As(III) removal, and raw material consumption, making it a promising approach for addressing arsenic contamination in wastewater treatment.