Multifunctional metal oxides synthesized via a solvo-hydrothermal process for photocatalytic degradation of organic dye and bacteria in wastewater

The persistent occurrence of textile industrial dyestuff in water bodies has continuously threatened aquatic life and public health, requiring effective remediation. This study explores the solvo-hydrothermal synthesis of Ag₂O, Fe₂O₃, AgFe₂O₃, TiO₂, Ag-TiO₂, Fe-TiO₂, and AgFe-TiO₂ catalysts. Various techniques, including SEM-EDS, FTIR, XRD, BET, TGA, and XPS characterized the as-prepared metal oxide (MO) catalysts. The multi-functionality of the catalysts was assessed on the degradation of Congo red dye and the inhibition of gram-positive B. subtilis in simulated wastewater. SEM analysis shows that MOs mostly appeared in granular morphologies except for Fe₂O₃, which comprised elongated grains, and showed that both Ag and Fe were successfully doped into the TiO₂ framework. The XRD survey revealed that Fe₂O₃ and TiO₂ were abundant in hematite and anatase phases. The BET findings indicated that the MOs are fine mesoporous particles, with TiO₂ showing the highest surface area of 83 m²/g, followed by 63, 28.27, and 24.03 m²/g for AgFe-TiO₂, AgFe₂O₃, and Ag-TiO₂, respectively. The antibacterial assays showed that Ag-TiO₂ and AgFe₂O₃ inhibited 58 % and 64 % of B. subtilis, correspondingly. The highest removals 98 and 99.99 % of Congo red (CR) dye were achieved with AgFe₂O₃ and TiO₂ after 5 h of irradiation time. At optimum conditions, AgFe₂O₃ and TiO₂ performed well and reached complete degradation up to 3 cycles. The outcomes of this study show that the multifunctional metal oxides produced via the solvo-hydrothermal method are thermally stable and can effectively be used for the simultaneous degradation of organic dye and disinfection of bacterial-polluted water.