Metal oxide/sulfide monoliths are a preferable choice of catalyst for photocatalytic degradation of organic pollutants owing to the single rock-like structure. Monolithic photocatalysts have hierarchical porosity, improved transport kinetics and are easily recoverable after the photocatalytic reaction. Sb2S3/SiO2 monoliths were synthesized via wet-impregnation of SbCl3 solution in SiO2 monoliths under vacuum conditions. The formation of crystalline Sb2S3/SiO2 monoliths was confirmed using XRD while XPS analyses were performed to know the oxidation states of the constituent elements. BET-BJH analyses revealed that the monoliths had surface area of ~83 m2/g and mesopore diameter was around 13.61 nm. FESEM analysis manifested porous network structure of SiO2 monoliths and ‘Mimosa Pudica’ nanoflower-like morphology of Sb2S3/SiO2 monoliths. The UV-Vis DRS and PL spectroscopies revealed that the material has a narrow band gap (1.57 eV) and a reduced recombination rate of e−/h+ pair in comparison to bulk Sb2S3 powder. The thermal stability of the materials was investigated using TGA. The photocatalytic performance of the monolith was evaluated by photocatalytic degradation of insecticide, Thiamethoxam (TM) at various catalyst concentrations and different pH values. About 70% TM was degraded with a rate constant of 0.0057 min−1 within 180 min under UV light irradiation at optimum conditions i.e., pH 3 and catalyst concentration ~0.05 g/L. Various scavengers like DMSO, benzoquinone, IPA, and methanol were used to discover the major active species in the photodegradation mechanism revealing that holes were the dominant species. The photocatalytic treatment of raw textile effluent was done and ~97% TOC and ~92% COD-removal was achieved showing that this photocatalyst is better than physicochemical treatment done by industries. The study aims at synthesizing economical, proficient and reusable photocatalyst for wastewater treatment that has the potential to be translated at large scale for practical applications.

Sb2S3/SiO2 monolith at centimeter-level for photocatalytic abatement of thiamethoxam from aqueous media

ACS Spring Meeting 2021

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