Biotite and ZnO embedded carbon aerogel composite for enhanced photocatalytic activity to degrade ciprofloxacin under sunlight stimulation

Abstract

This study was explored the photocatalytic efficiency of biotite and ZnO embedded carbon aerogel (CA) photocatalyst to degrade ciprofloxacin (CIP) antibiotic from an aqueous medium by sunlight harvesting. CA came from waste newspaper through pyrolysis technique. Biotite was extracted from Bramapurta River's sand through high-tension magnetic separation techniques. The developed catalyst was characterized by applying FESEM, EDS, XRD, and XPS. The bandgap (1.69 eV) of the catalyst was determined from Tauc's plot. The photocatalytic study showed that, optimum degradation was achieved at 98.471 %, 84.576 %, 77.997 % and 59.607 % for 2, 5, 10 and 20 mg/L CIP containing solution respectively in 180 min at its natural pH applying only employing 0.25 g/L dosage. Moreover, in the pH study, catalyst showed maximum degradation 88.773 % for 5 mg/L CIP containing solution at pH 7 exposing the same irradiation time and dosage. The degradation followed pseudo-first-order kinetics with a maximum rate constant of 0.01831 min−1 which attributes to the first degradation of CIP through ROS. The scavenger test suggested that •OH− and e− played a vital role in the photodegradation process. Regeneration studies confirmed that photocatalysts showed better degradation efficiency until five cycles. Fusion of metal oxides in the catalyst might play a vital role in the multiple photodegradation cycles without losing stability of the composite. FESEM, EDS, and XPS characterization of the spent catalyst was performed for understanding its morphological and chemical change. An antimicrobial study was performed to confirm its efficiency against of gram-negative bacteria (E. coli) and gram-positive bacteria (S. aureus), which suggested that the catalyst is very effective in destroying gram-negative bacteria compared to gram-positive bacteria.