Visible-light-induced photocatalytic response of easily recoverable Mn2O3/SiO2 monolith in centimeter-scale towards degradation of ofloxacin: Performance evaluation and product analysis

Abstract

Monolithic-photocatalysts being easily recoverable are a suitable alternative to powdered materials for pollutant treatment. This study was conducted to prepare Mn2O3/SiO2 monoliths by wet-impregnating Mn(NO3)2․4H2O in SiO2 monoliths. The crystallinity of oxide was affirmed via XRD analyses, whereas EDS and elemental-mapping, and XPS studies revealed the constituent elements and their oxidation states. FESEM images confirmed porous morphology, while BET-analysis confirmed its mesoporous nature (∼8.44 nm) and enormous surface area (∼241 m2/g). The DRS and PL studies disclosed that Mn2O3/SiO2 monoliths consisted of narrow band-gap of ∼2.14 eV and had suitable electron/hole separation. The photocatalytic effectiveness of the monolith had been checked by degrading model dye methylene blue (MB) and antibiotic ofloxacin (OF). The influence of various reaction parameters for degradation, i.e., monolith dose, solution-pH, illumination-area, scavengers, etc., was noted. At optimal reaction conditions, outstanding competence was achieved for MB (95.23%; 0.0225 min−1) and decent results were obtained for OF-degradation (73.2%; 0.0096 min−1). The recyclable nature of the catalyst (∼12.7%-reduction in effectiveness after 10 successive cycles) was vindicated by several characterization studies after reusability. The O2•−radicals participated majorly in the degradation reaction. The reaction intermediates plus products, generated after the degradation of had been identified via LC/MS study. The mineralization extent of the OF and MB was also gauged through TOC analyses. The photocatalytic treatment of raw textile wastewater manifested ∼57.8% COD and 53% TOC-removal. This study emphasizes the competence of Mn2O3/SiO2 monoliths for the photocatalytic abatement of refractory organic contaminants.