Innovative grey water treatment using eco-friendly bio-photocatalyst AgCuFe2O4@chitosan in the presence of synergistic effects of persulfate activation: optimization and mechanisms.

In this study, AgCuFe2O4@Chitosan bio-photocatalyst was synthesized to make the most of environmental benignity and chemical stability for advanced greywater applications. The photocatalyst was evaluated under UV irradiation by synergistic activation of persulfate. FESEM, EDS-Mapping, and BET analyses showed quasi-spherical nanoparticles with a homogeneous size distribution, homogenous elements dispersion, and 15.305 m2/g surface area. XRD analysis confirmed that Ag and Cu were effectively incorporated into the chitosan matrix, which increased its crystallinity and stability. The photocatalyst showed a good magnetic property with an Ms. value equal to 17.13 emu/g, which helped in its easy retrieval and reuse. The TGA analysis demonstrated that the bio-composite had high thermal stability up to 600 °C. The optimal treatment conditions were a pH of 3, 2 mM persulfate, and 0.8 g/L photocatalyst dosage, where COD removal efficiencies were 82.9 % and 73.7 %, for synthetic and natural greywater, correspondingly. During the degradation process, greywater followed a pseudo-first-order kinetic model, where both sulfate and hydroxyl radicals played key roles in the elimination of COD. Moreover, the bio-photocatalyst was very reusable up to more than a few runs of treatment cycles with very good performance, underpinning the possible applications in the greywater treatment process in a sustainable manner.