Novel Fe-TiO2 composite driven dual effect for reduction in treatment time of pentoxifylline: Slurry to immobilized approach

Abstract

Attempts have been made to reduce the treatment time for degradation of pentoxifylline (PEN) using novel Fe-TiO2 composite by incorporating dual effect (photocatalysis and photo-Fenton). Waste foundry sand (FS) and fly ash (FA) was used as alternative iron source along with TiO2 either in suspended or supported form. Initially, dual effect was executed in slurry mode where 49% synergy was obtained for degrading PEN along with reduction in treatment time from 90 to 30min. In the subsequent experiments, FA/FS was entrapped in small pockets made of fine cotton cloth keeping TiO2 either in suspension or immobilized on clay beads. Significant improvements over the first order rate constant (k) were achieved for the dual process along with reduction in treatment time. Even two to threefold increase in ‘k’ was observed using novel Fe-TiO2 composite for the degradation of PEN confirming in-situ dual effect. The existence of TiO2 as well as iron on the composite surface even after 45 recycles was confirmed through SEM/EDS, XRD and diffuse reflectance spectroscopy. The mineralization of PEN was validated by reduction in COD and TOC along with the production of several anions. While intermediates formed during the degradation of PEN were identified through GC–MS analysis.