Fabrication and Characterization of CA/SA‐ZnO Nanocomposite Membrane Embedded With <i>Carica papaya</i> ‐Mediated ZnO Nanoparticles for Sunlight‐Driven Dye Removal

ABSTRACT In this study, zinc oxide nanoparticles (ZnO NPs) were successfully synthesized via a green synthesis approach using Carica papaya seed extract and subsequently incorporated into a cellulose acetate/stearic acid (CA/SA) matrix to fabricate a CA/SA‐ZnO composite membrane through the phase inversion method. The synthesized ZnO nanoparticles exhibited an average particle size &lt; 23 nm and a specific surface area of 32.528 m 2 g − 1 , indicating their nanoscale characteristics. The structural, morphological, and chemical properties of the prepared membranes were systematically characterized using FTIR, XRD, SEM–EDS, and XPS analyses, confirming the successful incorporation and uniform distribution of ZnO nanoparticles within the polymeric network. The photocatalytic activity of CA/SA‐ZnO membrane was investigated for methylene blue (MB) degradation under natural sunlight irradiation. The membrane achieved a maximum degradation efficiency of 96.43% under optimized conditions of 10 ppm dye concentration, pH 6.5, and 90 min irradiation time. The degradation efficiency was significantly influenced by solution pH and initial dye concentration, with enhanced performance observed under near‐neutral to alkaline conditions. Furthermore, the membrane retained more than 83% of its photocatalytic efficiency after repeated use. The obtained findings suggest that the developed CA/SA‐ZnO composite membrane is efficient for sunlight‐assisted degradation of MB dye in aqueous media.