Potential use of waste foundry sand in dual process (photocatalysis and photo-Fenton) for the effective removal of phenazone from water: Slurry and fixed-bed approach.

In this study, degradation of a pharmaceutical drug, Phenazone (PNZ) has been carried out via heterogeneous photocatalysis, photo-Fenton and in-situ dual process (photocatalysis + photo-Fenton) in suspension and fixed-mode under artificial UV-A as well as under natural solar radiations. Waste material such as foundry sand (FS) was exploited as a supplement for iron in case of photo-Fenton reaction. The distinct processes including photocatalysis and photo-Fenton were found to be competent for the degradation of PNZ as both processes revealed an almost 90-95% removal of PNZ after 180 min of UV irradiations. The degradation was improved to a great extent with remarkable reduction in treatment time of PNZ to almost 105 min when these two individual processes were combined together within the same unit. An almost 14% synergy of dual process over distinct processes was obtained. For fixed-bed studies, TiO immobilized hollow circular composite disc already containing FS was utilized which yielded an almost 96% reduction in the concentration of PNZ after 4 h of solar irradiations. The disc was recycled 10 times and its stability and activity was confirmed through XRD, SEM/EDS, and DRS. The mineralization of PNZ was confirmed through significant reduction in COD and generation of anions during the treatment process. The transformation products were examined through GC-MS analysis. The novel technique of in-situ dual process especially in fixed-mode visualized in this study by employing renewable energy and durable catalyst can represent a viable solution to various industries for the treatment of wastewater comprising of bio-recalcitrant pollutants.