Vis-LED responsive floating Hematite/Bi4O5I2 decorated polyurethane foam for synergistic adsorption-photocatalysis of phenols

Slurry-based photocatalyst reactors often suffer from secondary pollution due to catalyst leaching and low reusability, resulting from inefficient catalyst recovery. In this context, a visible light-driven Hematite/Bi₄O₅I₂ (HBI) nanocomposite was decorated on porous polyurethane foam (PU). The HBI nanocomposite was prepared by facile room temperature chemical precipitation, subsequently immobilized on PU via an eloquent chemical deposition technique. The inherent floating property of PU supported the mass transfer within the reactor, which could be attributed to the heat-induced convection across the HBI@PU  bed depth and stirring-induced convection throughout the phenolic solution. Thus, facilitating the transportation of pollutants and reactive species to the catalyst surface. As a result, the adsorption and photocatalysis were enhanced simultaneously. Moreover, the as-synthesized HBI and HBI@PU materials were characterized thoroughly using various techniques, including XRD, SEM, TEM, UV-DRS, and XPS. Furthermore, the photocatalysis of phenolics using HBI@PU was evaluated under optimal conditions: initial concentration of phenolics, 10 ppm; weight of catalyst material used, 0.25 g; pH, 6.2; and photocatalysis time, 80 min. The open-pore structure of the PU foam significantly enhanced the adsorption of phenolics, indicating that the foam provides additional porosity and adsorption sites. Consequently, the overall recorded removal of BPA, m-cresol, and phenol was 92.07 ± 1.53%, 84.25 ± 2.59%, and 59.41 ± 2.14%, respectively. Notably, only a marginal drop in removal efficiency was observed after subsequent recycles of photocatalysis. Hence, the as-synthesised visible light-driven floating HBI@PU photocatalyst holds potential applications in green and sustainable environmental remediation.