Hydrothermal Synthesis of FeS2 as a High-Efficiency Fenton Reagent to Degrade Alachlor via Superoxide-Mediated Fe(II)/Fe(III) Cycle

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• 作者：Wei Liu ; Yueyao Wang ; Zhihui Ai ; Lizhi Zhang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2015
• 出版时间：December 30, 2015
• 年：2015
• 卷：7
• 期：51
• 页码：28534-28544
• 全文大小：795K
• ISSN：1944-8252

文摘

In this study, we demonstrate that hydrothermally synthesized FeS₂ (syn-FeS₂) is highly efficient at catalyzing the H₂O₂ decomposition for alachlor degradation at a wide range of initial pH (3.2–9.2). The alachlor degradation rate of syn-FeS₂ heterogeneous Fenton system was almost 55 times that of its commercial pyrite (com-FeS₂) counterpart at an initial pH of 6.2. Experimental results revealed that the alachlor oxidation enhancement in the syn-FeS₂ Fenton system was attributed to the molecular oxygen activation induced by more surface-bound ferrous ions on syn-FeS₂. The molecular oxygen activation process could generate superoxide anions to accelerate the Fe(II)/Fe(III) cycle on the syn-FeS₂ surface, which favored the H₂O₂ decomposition to generate more hydroxyl radicals for the alachlor oxidation. It was found that the hydroxyl radicals generation rate constant of syn-FeS₂ Fenton system was 71 times that of its com-FeS₂ counterpart, and even 1–3 orders of magnitude larger than those of commonly used Fe-bearing heterogeneous catalysts. We detected the alachlor degradation intermediates with gas chromatography–mass spectrometry to propose tentatively a possible alachlor degradation pathway. These interesting findings could provide some new insights on the molecular oxygen activation induced by FeS₂ minerals and the subsequent heterogeneous Fenton degradation of organic pollutants in the environment.