Perylene-based metal-organic frameworks-decorated Zinc Ferrite for enhanced photodegradation of malachite green in aqueous system

• A perylene-based MOF (Cr-PTC) was successfully synthesized and combined with ZnFe₂O₄. • The Cr-PTC/ZnFe₂O₄ composite was prepared via solvothermal method with varied mass ratios. • The composite exhibited a small crystal size (13–23 nm) and a narrow band gap (∼1.7 eV). • Cr-PTC/ZnFe₂O₄−2:1 had the highest surface area (208.8 m²/g) and pore volume (0.427 cm³/g). • Cr-PTC/ZnFe₂O₄−1:1 showed optimal degradation of malachite green (81.13 % at malachite green concentration of 40 mg/L, pH = 6, catalyst dosage of 0.5 g/L and 30 min reaction time). This study informs the characteristics and photocatalytic activity of novel Cr-PTC/ZnFe₂O₄ composites for the degradation of malachite green (MG) under visible light irradiation at acidic pH (pH 6). The metal-organic framework of Cr-PTC was synthesized via a solvothermal method using chromium chloride and perylene-3,4,9,10-tetracarboxylic ligands, while ZnFe₂O₄ nanoparticles were prepared via a green synthesis approach using Cucurbita moschata (pumpkin seed) extract as a capping agent. The obtained composites were prepared at various mass ratios of Cr-PTC to ZnFe₂O₄ (1:1, 1:2, 2:1) and characterized using FTIR, XRD, SEM-EDX, UV–Vis DRS, BET, and pHpzc. Among the tested materials, the Cr-PTC/ZnFe₂O₄ (1:1) composite showed the highest degradation efficiency (81.13 %) at malachite green concentration of 40 mg/L, pH = 6, catalyst dosage of 0.5 g/L, and irradiation time of 30 min, which was attributed to its large surface area (115.5 m²/g), optimal pore volume, and good surface charge characteristics. The as-synthesized ZnFe₂O₄ enhanced the release and formation of reactive oxygen species (ROS), while Cr-PTC facilitated dye adsorption and light harvesting. This study demonstrated the synergistic effect of MOF–metal oxide composites and provided a sustainable strategy to design effective photocatalysts to treat acidic dye-contaminated wastewater.