Green biosynthesis of ZnMn₂O₄ nanoparticles entrapped within polymeric gel matrix for highly efficient photocatalytic remediation of Bisphenol A

Nanotechnology contributes significantly to the removal of water pollutants by developing advanced materials and methods that efficiently degrade pollutants through advanced oxidation process. The purpose of this study is to create a new hydrogel nanocomposite made of Psyllium-Carboxymethyl cellulose and ZnMn₂O₄ nanoparticles (PsyCMC@ZnMn₂O₄ nanocomposite) that can both adsorb and break down the Bisphenol A (BPA), a global water pollutant. The prepared materials were characterised by the PXRD, FESEM, TEM, FTIR, XPS, Zeta potential, and photoluminescence techniques. The PsyCMC@ZnMn₂O₄ nanocomposite is a great photocatalyst because it has a high negative zeta value (-25.7 mV), small particle size (62.61 nm), and a narrow band gap (2.3 eV). The composite's lower PL intensity suggests a reduced electron/hole (e⁻/h⁺) recombination. The nanocomposite broke down BPA (up to 93%) into smaller, safer molecules under ideal conditions (25 mg of nanocomposite, 120 mgL⁻¹ of pollutants, 90 min of sunlight, and an acidic pH) as confirmed by GCMS analysis. It was found that the PsyCMC@ZnMn₂O₄ nanocomposite remained reusable for up to 8 consecutive cycles, demonstrating its high stability and sustainability. This research will further propel the development of biocompatible green nanocomposites on an industrial scale for use in waste water treatment.