Fabrication and environmental assessment of photo-assisted Fenton-like Fe/FBC catalyst utilizing mealworm frass waste

The massive generation of dye wastewater and mealworm waste has shown potential dangers. In this study, an innovative method was developed to fabricate an efficient photo-assisted Fenton-like heterogeneous catalyst, namely, iron (Fe)-loaded mealworms (the larvae of Tenebrio molitor Linnaeus) frass-based biochar (Fe/FBC). The physico-chemical properties were characterized by X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Brunsuer-Emmett-Teller, Raman spectroscopy, inductively coupled plasma spectroscopy, and N-2 sorption-desorption isotherms. The results revealed the successful loading of Fe(III) on Fe/FBC surface with a loaded content of 6.0 wt%, and increased graphitization degree with high surface area (90.65 m(2) g(-1)) appeared in Fe/FBC. Excellent removal efficiency toward malachite green (MG) dye (67% TOC within 5 min) and good recycling performance of Fe/FBC were observed in photo-assisted heterogeneous Fenton-like system, indicating that the aid of light irradiation may accelerate the heterogeneous Fenton-like reaction and realize the synergistic effect of enhanced MG degradation. Three key possible MG degradation pathways, involving N-de-methylation, hydroxylation, and destruction of the conjugated chromophore, were proposed based on the results of ultra-performance liquid chromatography-tandem mass spectrometry. Life cycle assessment study was applied to evaluate the environmental impacts of the following two disposal strategies for frass wastes: Fe/FBC catalyst facilitation (scenario A) and composting treatment (scenario B) at midpoint level. Regarding ten impact categories, scenario A produced lower environmental footprint compared to scenario B, indicating that the facilitation of Fe/FBC is a financially and environmentally viable strategy for relieving the greenhouse effect, energy crisis, water toxicity, and eutrophication. (C) 2020 Elsevier Ltd. All rights reserved.