Cr3+doped α-Fe2O3 nanoparticles for photodegradation of organic pollutants with their disinfection efficacy

Pristine and Cr-doped α-Fe₂O₃ nanoparticles were synthesized using a low-cost and simple one-step hydrothermal method without any precipitating agent. Cr-doped α-Fe₂O₃ was found to be a promising candidate for recyclable photocatalytic application for Tetracycline (TC) and Congo-red (CR) degradation under normal sunlight irradiation along with excellent antibacterial properties. Addition of Cr shows a significantly improved degradation efficiency from 20% to 91% in just 25 min for CR, while the degradation rate reached to 81% for TC, which was also monitored in real-time using internet of things (IoT). Also, a high degree of mineralization was achieved (∼87.9%), which was confirmed using total organic carbon (TOC) content. In parallel, the biochemical oxygen demand/chemical oxygen demand (BOD₅/COD) ratio confirmed the fast degradation efficiency using a small amount of catalytic dosage (∼ 0.40 g/L). Also, degradation of multiple dyes provides a promising avenue for addressing complex waste water treatment challenges. Moreover, Cr-doped α-Fe₂O₃ displays excellent antibacterial activity towards E.coli and E.Faecium. Major factors involved in sunlight driven photocatalytic activity for example absorbance range, porosity, separation between e^--h⁺, and charge transfer property were surprisingly improved by Cr doping and henceforth increased photocatalytic activity and antibacterial properties. This work highlights the potential utilization of Cr-doped α-Fe₂O₃ for the purification and disinfection of industrial waste water.