Persulfate assisted photocatalytic and antibacterial activity of TiO2–CuO coupled with graphene oxide and reduced graphene oxide
Charitha Thambiliyagodage, Heshan Liyanaarachchi, Madara Jayanetti, Geethma Ekanayake, Amavin Mendis, Upeka Samarakoon, S. Vigneswaran
Abstract
Abstract Photocatalysts of TiO 2 –CuO coupled with 30% graphene oxide (GO) were hydrothermally fabricated, which varied the TiO 2 to CuO weight ratios to 1:4, 1:2, 1:1, 2:1 and 4:1 and reduced to form TiO 2 –CuO/reduced graphene oxide (rGO) photocatalysts. They were characterized using XRD, TEM, SEM, XPS, Raman, and DRS technologies. TiO 2 –CuO composites and TiO 2 –CuO/GO degrade methylene blue when persulfate ions are present. Persulfate concentration ranged from 1, 2, 4 to 8 mmol/dm −3 in which the highest activity of 4.4 × 10 –2 and 7.35 × 10 –2 min −1 was obtained with 4 mmol/dm −3 for TiO 2 –CuO (1:4) and TiO 2 –CuO/GO (1:1), respectively. The presence of EDTA and isopropyl alcohol reduced the photodegradation. TiO 2 –CuO coupled with rGO coagulates methylene blue in the presence of persulfate ions and such coagulation is independent of light. The catalyst dosage and the concentration of the dye were varied for the best-performing samples. The antibacterial activity of the synthesized samples was evaluated against the growth of Escherichia coli , Staphylococcus aureus , Pseudomonas aeruginosa and Klebsiella pneumonia . Ti:Cu (1:2)-GO and Ti:Cu (1:4)-GO had the highest antibacterial activity against K . pneumoniae (16.08 ± 0.14 mm), P . aeruginosa (22.33 ± 0.58 mm), E . coli (16.17 ± 0.29 mm) and S . aureus (16.08 ± 0.88).