Photo-Fenton system Fe₃O₄/NiCu₂S₄ QDs towards bromoxynil and cefixime degradation: A realistic approach

The contamination of natural water bodies with toxic pollutants are alarmingly increasing in recent decades. The development of advanced wastewater treatment techniques and their utilization is sought for the effective removal of pollutants especially pharmaceutical and pesticide compounds (PPCs). The present study focused on the green synthesis of a novel heterojunction NiCu₂S₄ QDs@Fe₃O₄ nanocomposite (NCs) using Dunica erecta plant extract for the photo-Fenton catalytic degradation of bromoxynil (BRX) and cefixime (CEF). The morphological, structural, and physiochemical properties of the fabricated nanomaterial were analysed via SEM, TEM, XRD, FTIR, Raman, UV–Vis DRS, BET, PL, EIS, and ESR spectroscopy techniques. The NiCu₂S₄ QDs@30% Fe₃O₄ showed 97.5 and 81% degradation of BRX and CEF within 200 and 180 min of visible light irradiation, respectively. The excellent photocatalytic efficiency of NCs was attributed to high visible light harvesting ability, efficient charge carriers’ separation, and migration across the heterostructure interface. Various initial parameters including nanomaterial dosage, pollutant concentration, pH, and ions were optimized. A possible photodegradation pathway was predicted based on the intermediates identified from GC-MS/MS analysis, and their non-toxic nature on daphnia, green algae, and fishes was determined by the ECOSAR program. The fabricated NiCu₂S₄ QDs@Fe₃O₄ NCs have shown excellent reusability efficiency of 98.7%. The reusability and structural stability were confirmed by six-cycle experiments, XRD, and XPS analysis. In addition, the photocatalyst exhibited 99% of degradation of industrial effluent. The prepared NiCu₂S₄ QDs@Fe₃O₄ NCs with superior photocatalytic performance can be used as a promising photocatalyst for the treatment of industrial effluents.