A Novel concept of in-situ dual effect (photocatalysis and photo-Fenton) in fixed mode for the degradation of pharmaceutical compounds.

Abstract

Novel composite clay beads combined with foundry sand (FS) /fly-ash (FA) were taken as the support materials for fixing the TiO2 and have been subsequently used as an iron source. The in-situ generation of iron in case of beads that are composed of either FS /FA or both induced dual effect (photocatalysis and photo-Fenton) in the same degradation unit thus produces a synergistic effect for the reduction in the concentration of antibiotic Ofloxacin. Composite beads (FS/FA/TiO2) showed relatively best results (92% degradation) at optimized conditions with 300mg /L H2O2 dose, 3.8 pH and 25W /m2 UV intensity in the batch reactor experiments. The enhancements over the first order rate constant (k) were accomplished for the dual effect along with a decrease in treatment time. Indeed, even a few overlay increments in ‘k' value was observed by utilizing novel Fe-TiO2 complex for the ofloxacin reduction affirming in-situ double impact. The stability of the catalyst after 40 recycles was observed through SEM /EDAX and FTIR analysis which further justified its use in the field-scale applications. Further, mineralization of ofloxacin was validated by estimation of nitrate, nitrite and ammonia as it's by-products and along with generation of various anions i.e., total iron, ferric and ferrous ion determination, the intermediate products were also identified through GC–MS analysis. With these results, subsequently, the concept has been introduced for the treatment of real pharmaceutical effluent. The COD of the real effluent from a local pharmaceutical industry was reduced from 1076 mg/L to 279 mg/L using novel composite beads.