Synergistic effect of dual process (photocatalysis and photo-Fenton) for the degradation of Cephalexin using TiO2 immobilized novel clay beads with waste fly ash/foundry sand

Novel composite clay beads mixed with foundry sand (FS)/fly-ash (FA) were used as support materials for fixing the catalyst TiO2 and subsequently used as iron source. The in-situ iron generation in case of beads that contained either FS/FA or both induced dual effect (photo-Fenton and photocatalysis) in the same treatment unit thus leading to synergistic effect for the degradation of antibiotic Cephalexin. Composite beads (FS/FA/TiO2) showed relatively best results (89% degradation) as compared to FS/TiO2 (79%) or FA/TiO2 (81%) at optimized conditions. From the kinetics data, there was 30-45% increase in first order rate constant in case of FS/FA/TiO2 beads pertaining to dual effect. The stability of the catalyst even after 35 recycles, as confirmed through SEM/EDS and XRD analysis; justified its claim for field-scale applications. Further, mineralization of pollutant was validated by reduction in COD (82%) along with generation of various anions whereas intermediate products were identified through GC-MS analysis. (C) 2017 Elsevier B.V. All rights reserved.