Abstract

SummaryAdvanced oxidation processes (AOPs) based on sulfate radicals (SO4⋅−) suffer from low conversion rate of Fe(III) to Fe(II) and produce a large amount of iron sludge as waste. Herein, we show that by using MoO2 as a cocatalyst, the rate of Fe(III)/Fe(II) cycling in PMS system accelerated significantly, with a reaction rate constant 50 times that of PMS/Fe(II) system. Our results showed outstanding removal efficiency (96%) of L-RhB in 10 min with extremely low concentration of Fe(II) (0.036 mM), outperforming most reported SO4⋅−-based AOPs systems. Surface chemical analysis combined with density functional theory (DFT) calculation demonstrated that both Fe(III)/Fe(II) cycling and PMS activation occurred on the (110) crystal plane of MoO2, whereas the exposed active sites of Mo(IV) on MoO2 surface were responsible for accelerating PMS activation. Considering its performance, and non-toxicity, using MoO2 as a cocatalyst is a promising technique for large-scale practical environmental remediation.

Highlights

  • The presence of organic pollutants such as aromatic organic compounds in the environment is among the most significant issue for humans that requires immediate remediation (Muthuraman and Teng, 2009; Crini, 2006; Al-Ghouti et al, 2003)

  • Our results showed outstanding removal efficiency (96%) of lissaminerhodamine B (L-RhB) in 10 min with extremely low concentration of Fe(II) (0.036 mM), outperforming most reported SO4,À-based Advanced oxidation processes (AOPs) systems

  • Surface chemical analysis combined with density functional theory (DFT) calculation demonstrated that both Fe(III)/Fe(II) cycling and PMS activation occurred on the (110) crystal plane of MoO2, whereas the exposed active sites of Mo(IV) on MoO2 surface were responsible for accelerating PMS activation

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Summary

Introduction

The presence of organic pollutants such as aromatic organic compounds in the environment is among the most significant issue for humans that requires immediate remediation (Muthuraman and Teng, 2009; Crini, 2006; Al-Ghouti et al, 2003). Dionysiou et al found that PMS can be activated by various transition metals, among which Co(II) and Ru(III) demonstrated the best performances as catalysts for generating sulfate radicals (Anipsitakis and Dionysiou, 2003, 2004). Their high toxicity and scarcity significantly limited their implementation in PMS activation system. The activation of PMS by Fe(III) will produce SO5,À (1.1 eV) under acidic conditions (Equation 2), greatly decreasing its oxidation capacity (Anipsitakis and Dionysiou, 2004)

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