Antibacterial and photocatalytic activities of fruit-extract-mediated synthesized ZnO nanoparticles

ZnO nanoparticles were produced using Morinda citrifolia fruit extract and evaluated for their performance in the removal of Congo red (CR) dye under visible light, as well as their antibacterial activity against different pathogenic strains. The ZnO photocatalyst was characterized according to crystallinity, surface elements and morphology. Various factors related to photocatalytic activity, namely contact time, photocatalyst dosage, initial CR concentration, and pH, were investigated. Under optimal conditions, a moderate ZnO loading achieved a high CR degradation efficiency of 95.23% within 60 min of light irradiation, as determined using response surface methodology (RSM) coupled with face-centered design (CCF). Additionally, a scavenger study confirmed that superoxide radicals (˙O₂ ^-) and holes (h⁺) were major reactive species in the photodegradation of CR. Furthermore, the antibacterial activity was remarkable, with the highest inhibition zone measuring 20.7 mm against Salmonella typhimurium. This study provides a promising approach for developing highly efficient photocatalysts with strong adsorption capabilities whilst also broadening their application as antibacterial agents.