High-efficiency SrTiO3·Al/CoOOH-PSF/PVDF photocatalytic membrane for synergistic degradation of organic pollutants

Abstract

Photocatalytic membrane technology, synergizing membrane separation with photocatalysis, offers a promising approach to address challenges in advanced water treatment, including catalyst recovery and membrane fouling mitigation. In this work, an SrTiO₃·Al/CoOOH photocatalyst was synthesized via a high-temperature solid-state method followed by photodeposition of CoOOH. A composite photocatalytic membrane was fabricated by immobilizing SrTiO₃·Al/CoOOH onto a polysulfone (PSF)/polyvinylidene fluoride (PVDF) substrate through a phase inversion process. The material’s crystallinity, elemental composition, optical properties, and charge transfer behavior were thoroughly characterized using techniques including X-ray diffraction, scanning/transmission electron microscopy (SEM/TEM), X-ray photoelectron spectroscopy, UV–visible absorption spectroscopy (UV–Vis), Mott–Schottky (M-S) curves, photoluminescence spectroscopy, and electrochemical impedance spectroscopy. Characterization results demonstrate that Al³⁺ doping transforms the SrTiO₃ morphology from polyhedral particles to cubic structures and induces a positive shift of 0.44 and 0.43 eV in valence band maximum and conduction band minimum, respectively. Crucially, Al³⁺ doping synergistically enhances photogenerated charge carrier separation on SrTiO₃ when coupled with the CoOOH cocatalyst. All prepared membranes achieved a 100% rejection rate for Congo red. Notably, the water flux of the SrTiO₃·Al/CoOOH-PSF/PVDF membrane is 3.7 times that of the PSF/PVDF membrane. Furthermore, after 150 min of operation, the SrTiO₃·Al/CoOOH-PSF/PVDF membrane maintained 81.3% of its initial flux, compared to only 41.7% for the PSF/PVDF membrane. The optimized SrTiO₃·Al/CoOOH-PSF/PVDF membrane exhibited exceptional photocatalytic performance and stability, achieving 93.6% degradation of Congo red within the first reaction cycle (150 min) and 82.7% in the fourth cycle (600 min) under simulated sunlight. Additionally, the membrane also exhibited effective degradation performance toward antibiotic pollutants. This study provides a photocatalytic membrane with promising application prospects for industrial wastewater remediation.