Synthesis of Magnetic Nanoparticles for the Photodegradation of Organic Pollutants in Wastewater Treatment

Wastewater treatment remains a significant environmental challenge owing to the widespread presence of persistent organic pollutants. Among various remediation technologies, photocatalytic degradation has attracted considerable attention as an efficient, sustainable, and cost-effective approach for pollutant removal. In this study, tin ferrite (SnFe₂O₄, TF) nanoparticles were successfully synthesized via a low-cost co-precipitation method coupled with a simple interfacial reaction at room temperature. Subsequently, TF nanoparticles were decorated with zinc oxide (ZnO) through a green synthesis route to fabricate novel SnFe₂O₄/ZnO (ZTF) nanocomposites. Furthermore, carbon quantum dots (CQDs) were incorporated onto the ZTF nanocomposites, resulting in the formation of SnFe₂O₄/ZnO/CQDs (ZTF/CQDs) ternary nanostructures. The photocatalytic performance of the synthesized materials was evaluated through the degradation of methylene blue (MB) dye under 420 nm visible-light irradiation, with the degradation process monitored using UV-Visible spectroscopy. The ZTF/CQDs nanostructures exhibited outstanding photocatalytic activity, achieving a degradation efficiency of 91.29% within 60 min of irradiation. The incorporation of CQDs and ZnO effectively enhanced charge separation and light-harvesting capability, leading to improved photocatalytic performance. In addition, the magnetic nature inherited from TF nanoparticles imparted excellent recyclability to the photocatalyst, allowing rapid and convenient recovery using an external magnetic field. Kinetic studies demonstrated a strong agreement with the Dubinin-Radushkevich (D-R) isotherm model, yielding a correlation coefficient (R²) of 0.991. Brunauer-Emmett-Teller (BET) analysis revealed a high specific surface area of 125.1 m² g⁻¹, which significantly contributed to the enhanced photocatalytic efficiency. Comprehensive characterization of the synthesized nanostructures was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), BET surface area analysis, and zeta potential measurements. The findings demonstrate that ZTF/CQDs nanostructures are promising, magnetically recoverable photocatalysts for the efficient degradation of organic pollutants in wastewater treatment applications.