BIOREDUCTION OF HEXAVALENT CHROMIUM BY AQUEOUS FLOWER WASTE EXTRACTS: A SUSTAINABLE APPROACH WITH ANTIOXIDANT AND ANTIMICROBIAL BENEFITS

Hexavalent chromium [Cr(VI)] is a widespread and hazardous pollutant released by several industrial processes, posing severe risks to ecosystems and human health. In this study, aqueous (AFW) and ethanolic (EFW) extracts from waste flowers were evaluated for their potential to reduce Cr(VI) to its less toxic trivalent form [Cr(III)] under environmentally friendly conditions. Phytochemical analysis revealed the presence of phenolics, flavonoids, tannins, and alkaloids in both extracts. Antioxidant assays (DPPH, ABTS, FRAP) demonstrated that AFW possessed superior radical scavenging and reducing potential compared to EFW. GC-MS analysis identified 37 and 33 bioactive compounds in AFW and EFW, respectively. Among the two, AFW exhibited significantly higher Cr(VI) reduction efficiency, achieving a maximum of 67% reduction at 5 mg/mL for 10 ppm Cr(VI) after 30 minutes of incubation at pH 7 and 37 °C. The reduction followed first-order kinetics. Additionally, AFW demonstrated moderate antibacterial activity against Enterococcus faecalis and Staphylococcus aureus, showing dose-dependent zones of inhibition. These findings highlight that phytochemicals derived from floral waste offer a sustainable, cost-effective, and multipurpose approach for Cr(VI) detoxification, with added antioxidant and antibacterial properties relevant to both environmental remediation and biomedical applications.