Quince (Cydonia oblonga) seed hydrogel-based green synthesis of copper oxide nanoparticles for photocatalytic degradation of methylene blue and methyl orange

Organic dyes discharged from various industries pose a significant hazard to humans and the environment, and a valid approach is needed to remove dangerous and harmful substances from industrial effluents. The present study synthesized novel CuO nanoparticles (CuO NPs) using a hydrogel derived from C. oblonga seeds. The green synthesis of NPs was confirmed visually by the formation of black precipitates. The as-prepared NPs exhibited a prominent peak at wavelength 379 nm and an estimated band gap energy value of 4.23 eV. FTIR analysis revealed a distinguishing peak at 594 cm-1 -1 due to Cu-O stretching vibrations. The SEM images showed sheet- like NPs with an average size of 69 nm. Further, the EDX spectrum disclosed copper (31.1%) and oxygen (32.6%) as main elements. At optimized reaction conditions of irradiation time (120 min), catalyst load (5.0 mg), and dye solution (10 ppm), CuO NPs demonstrated significant degradation of methylene blue (88.2%) and methyl orange (83.1%), following pseudo-first-order kinetics. CuO NPs retained over 70% of their initial photocatalytic efficiency for up to three repetition cycles. Hence, C. oblonga seed hydrogel could be an excellent biomaterial for developing green, sustainable, and recyclable photocatalysts for environmentally favorable applications.