Concentration-Dependent Enhancing Effect of Dissolved Silicate on the Oxidative Degradation of Sulfamethazine by Zero-Valent Iron under Aerobic Conditions.,Environmental Science & Technology

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Concentration-Dependent Enhancing Effect of Dissolved Silicate on the Oxidative Degradation of Sulfamethazine by Zero-Valent Iron under Aerobic Conditions.
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2019-12-15 , DOI: 10.1021/acs.est.9b05904
Jiaxin Cui ₁ , Xu Wang ₁ , Kaiyuan Zheng ₁ , Dihua Wang ₁ , Hua Zhu ₁ , Xuhui Mao ₁

Affiliation

Dissolved silicate, as a ubiquitous inorganic component in natural waters, is reported to depress the reactivity of zero-valent iron (ZVI) for reductive reactions under anoxic conditions, but it is unclear if the same inhibitory effect occurs for a ZVI/O2 system. In this study, the role of dissolved silicate for the reactivity of micron-sized ZVI (mZVI) was revisited under aerobic conditions, and different observations were found. Silicate had a volcano-type enhancing effect on the performance of the ZVI/O2 system for sulfamethazine (SMT) degradation. The results showed that, under a circum-neutral or alkaline pH condition (pH 6.0-9.0), the presence of dissolved silicate could significantly enhance the degradation of SMT because silicate coordinated with ferrous ions and further led to the generation of reactive oxygen species (ROS). This study suggests that silicate can act as both a ligand and corrosion inhibitor in a ZVI/O2 system: the coordination of silicate and ferrous iron accelerated the oxidative degradation of organic pollutants in an oxic aqueous solution, while the corrosion inhibitory effect of surface-bound silicate at higher concentrations may decrease the reactivity of the ZVI/O2 system, thereby offsetting the enhancing effect from the silicate-coordinated ferrous iron. This study not only redefines the role of naturally occurring silicate for a ZVI reaction system but also gives clues to develop high-efficiency ZVI/O2 technologies for water remediation.

中文翻译：

在好氧条件下，溶解硅酸盐对零价铁氧化降解磺胺二甲嘧啶的浓度依赖性增强作用。

据报道，溶解的硅酸盐作为天然水中普遍存在的无机成分，会抑制缺氧条件下零价铁（ZVI）的还原反应活性，但目前尚不清楚ZVI / O2系统是否会产生同样的抑制作用。在这项研究中，在有氧条件下重新探讨了溶解硅酸盐对微米级ZVI（mZVI）反应性的作用，并发现了不同的观察结果。硅酸盐对ZVI / O2系统对磺胺二甲嘧啶（SMT）降解的性能具有火山作用。结果表明，在环境中性或碱性pH条件下（pH 6.0-9.0），溶解的硅酸盐的存在可以显着增强SMT的降解，因为硅酸盐与亚铁离子配位并进一步导致了活性氧的产生（ ROS）。这项研究表明，硅酸盐可以在ZVI / O2系统中同时充当配体和腐蚀抑制剂：硅酸盐和亚铁的配位加速了含氧水溶液中有机污染物的氧化降解，而表面结合的缓蚀作用较高浓度的硅酸盐可能会降低ZVI / O2系统的反应性，从而抵消了硅酸盐配位的二价铁的增强作用。这项研究不仅重新定义了天然硅酸盐在ZVI反应系统中的作用，而且为开发用于水修复的高效ZVI / O2技术提供了线索。硅酸盐和亚铁的配位加速了含氧水溶液中有机污染物的氧化降解，而高浓度表面结合的硅酸盐的腐蚀抑制作用可能会降低ZVI / O2系统的反应性，从而抵消了ZVI / O2体系的增强作用。硅酸盐配位的亚铁。这项研究不仅重新定义了天然硅酸盐在ZVI反应系统中的作用，而且为开发用于水修复的高效ZVI / O2技术提供了线索。硅酸盐和亚铁的配位加速了含氧水溶液中有机污染物的氧化降解，而高浓度表面结合的硅酸盐的腐蚀抑制作用可能会降低ZVI / O2系统的反应性，从而抵消了ZVI / O2体系的增强作用。硅酸盐配位的亚铁。这项研究不仅重新定义了天然硅酸盐在ZVI反应系统中的作用，而且为开发用于水修复的高效ZVI / O2技术提供了线索。

更新日期：2019-12-29

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