Abstract
The potential use of novel iron based mineral catalysts as an effective and available material for electrocatalytic oxidation of refractory contaminants by heterogeneous electro-Fenton (HEF) process was studied for the first time. For this purpose, four natural catalysts, namely ilmenite (FeTiO3), pyrite (FeS2), chromite (FeCr2O4), and chalcopyrite (CuFeS2) were selected as the source of ferrous iron (Fe2+) ions. The catalyst samples were appropriately characterized by X-ray diffraction (XRD) and RAMAN analysis. The degradation kinetics and mineralization rate of 0.2 mM antibiotic cefazolin (CFZ), as a contaminant of emerging concern, were comparatively investigated by HEF using the catalysts mentioned above. The effect of important experimental parameters such as catalysts loading and current on the process efficiency was investigated. Moreover, the performance of these new mineral catalysts was compared in term of CFZ degradation kinetics, mineralization power, mineralization current efficiency and electrical energy consumption. A greater enhancement in degradation/mineralization of CFZ was obtained when using chalcopyrite as the catalyst in HEF. The stability and reusability experiments demonstrated negligible decrease in catalytic activity of chalcopyrite after five consecutive runs. Besides, the rate constant for CFZ oxidation by hydroxyl radicals was estimated according the pseudo-first-order reaction kinetics. The empirical assessment, in addition to economic evaluation, confirmed that iron based mineral catalysts and specifically chalcopyrite could be an appropriate and cost-effective alternative catalyst for HEF due to its high catalytic activity, availability, eco-friendly nature and low energy consumption compared to other synthesized catalysts.
Highlights
The presence of pharmaceuticals in effluents is mainly the result of ineffective removal technologies used in conventional wastewater treatment plants [14,15,16]
In comparison with Joint Committee on Powder Diffraction Standards (JCPDS) data, the main peak positions in Figure 1a are in good agreement with characteristic peaks of ilmenite at about 24.1, 27.7, 32.9, 35.6, 40.6, 44.5, 49.1, 53.4, 56.6, 61.9, 63.7, 70.5 and 74.8 (JCPDS No 98-001-7090)
The The chemical structures of of iron-based catalysts confirmed by X-ray diffraction (XRD)
Summary
Cefazolin (CFZ) is an antibiotic prescribed for the treatment of several bacterial diseases in the stomach, lung, bones, joints, and urinary tract [9,10]. It is present in surface and ground water in the range of ng L−1 to μg L−1 [11,12,13]. The presence of pharmaceuticals in effluents is mainly the result of ineffective removal technologies used in conventional wastewater treatment plants [14,15,16]
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