Novel insights into ferrate (VI) activation by Mn-modified sludge biochar for sulfamethoxazole degradation: Dominance of hydroxyl group and Mn-O bond in the non-radical pathway

文献类型： 外文期刊

第一作者： Deng, Zhikang

作者： Deng, Zhikang;Ma, Yongfei;Zhu, Jinyao;Liu, Yifan;Zhang, Zulin;Li, Ping;Zhang, Zulin

作者机构：

关键词： Ferrate (VI); SMX; DFT; Biochar; High-valent iron

期刊名称：SEPARATION AND PURIFICATION TECHNOLOGY （ 影响因子：8.1； 五年影响因子：7.6 ）

ISSN： 1383-5866

年卷期： 2024 年 349 卷

页码：

收录情况： SCI

摘要： Ferrate (Fe (VI)), as a versatile oxidizer, has been widely employed for water treatment. However, the rapid selfdecomposition of Fe (VI) diminishes its practical application efficiency. In this study, a novel Mn-modified sludge biochar (MSBC) was synthesized for the first time to activate Fe (VI) and generate highly reactive Fe (IV)/Fe (V) for the rapid removal of sulfamethoxazole (SMX). The results showed that MSBC (0.10 g/L) effectively activated Fe (VI) (100 mu M), and 87.39 % of SMX (10 mu M) and 40.26 % of total organic carbon (TOC) were removed within 10 min. Notably, raising the solution pH (e.g., from 6.0 to 11.0) would result in decreasing the reactivity of Fe (VI) and a lower removal efficiency of SMX. The quenching, electron paramagnetic resonance and probe experiments suggested that center dot O2- and high-valent iron species (Fe (V)/Fe (IV)) were identified as the major contributions to the removal of SMX. The detailed activation sites of MSBC were -OH and Mn-O, as corroborated by density functional theory (DFT) calculation and characterization. These activation sites facilitated activation of Fe (VI) through efficient electron transfer. The Fukui index indicated that the N, S, and O atom of SMX were the primary attacked sites. Subsequently, five potential degradation pathways were proposed, with the cleavage of the S-N bond being the predominant one. The toxicity of these products was examined using ECOSAR program, revealing that main products showed low toxicity or non-toxicity. The Cl-, SO42-, and NO3- had negligible effect on SMX degradation, although excessive concentrations of HCO3- and humic acid (HA) showed slightly inhibition. Additionally, the Fe (VI)/MSBC system also effectively removed 87.34 % of sulfadiazine (SDZ) and 93.91 % of sulfamethoxypyridazine (SMP). Overall, this study offered a practical and cost-effective approach for the activation of Fe (VI) and provided new insights to the degradation mechanism.

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