Bifunctional quaternary magnetic composite as efficient heterojunctions photocatalyst for simultaneous photocatalytic visible light degradation of dye and herbicide pollutants from water and bacterial disinfection

In the present study, the magnetic Fe3O4/Ag2C2O4/Ag3PO4/Ag nanocomposite were prepared through a simple co-precipitation method by using calendula officinalis seed extract as a stabilizer. The fabricated quaternary photocatalyst was applied for to degrade food dye Brilliant Blue FCF (BB) and herbicide Paraquat (PQ) as contaminants at binary mixture in a batch and continuous flow-loop photoreactor under visible light irradiation and also the antibacterial properties was investigated. The fabricated nanocomposite was determined by XRD, FESEM, EDX, BET&BJH, UV-DRS, FT-IR and VSM methods to gain insight about structure, morphology, purity, surface area, optical, functional group and magnetic properties. The photoelectrochemical experiments, PL and DRS indicate the successful coupling of the active semiconductors. The degradation efficiency of BB and PQ was announced to be 88.9% and 92.72% under optimal conditions with a high reaction rate constant value (0.03 and 0.0326 min−1), respectively. The quaternary photocatalyst exhibited superior photocatalytic performance compared with Ag3PO4/Ag2C2O4 and Ag2C2O4. Various scavengers were used to explore the mechanism of photocatalytic performance and supports that O2−. and OH. is main active species in the degradation process of BB and PQ, respectively. Furthermore, the Fe3O4/Ag2C2O4/Ag3PO4/Ag also demonstrated bactericidal activity against Staphylococcus aureus (S. aureus) as gram-positive bacteria and Escherichia coli (E. coli) as gram-negative bacteria. •The synthesis of Fe3O4/Ag2C2O4/Ag3PO4/Ag composite by using calendula officinalis seed extract as a stabilizer.•The magnetic composite were photo-degraded herbicide and dye in batch and continuous flow-loop photoreactor under visible light irradiation.•An excellent antibacterial activity of as-prepared photocatalyst was observed on gram negative and positive bacteria.•More than 88 and 99% of pollutants and bacteria are degraded under LED visible light irradiation, respectively.