Arak University Colloid & Nanoscience Journal 2980-9215 3 3 2025 11 01 Photocatalytic degradation of methylene blue and catalytic reduction of 4-nitrophenol using green-synthesized silver nanoparticles from orange peel pectin 696 706 733401 10.66224/CNJ.3.3.696 EN Mohammadali Pourmohammadi Mahunaki Department of Polymer Engineering, Faculty of Engineering, Qom University, Qom, Iran 0009-0000-0180-9993 Mohammad Hadi Meshkatalsadat Department of Chemistry, Qom University of Technology, Qom, Iran 0000-0002-0009-6132 Tayebeh Momeni Department of Chemistry, Qom University of Technology, Qom, Iran Journal Article 2026 02 10 Environmental contamination by organic pollutants, such as dyes and nitroaromatic compounds, poses significant health and ecological risks. In this study, pectin extracted from orange peels was utilized as a green reducing and stabilizing agent for the synthesis of silver nanoparticles (AgNPs). The generated nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), and transmission electron microscopy (TEM). The result verified the formation of uniformly spherical nanoparticles with an average size of ~20–30 nm. Then, The catalytic activity of AgNPs toward the reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄ as a reducing agent, as well as their photocatalytic activity in the degradation of methylene blue (MB) under visible-light irradiation, were investigated separately. The results demonstrated that, in the catalytic process, nearly complete conversion of 4-NP to 4-aminophenol (4-AP) was achieved within 15 min using 1 mL of AgNPs, while complete reduction occurred within 5 min when the catalyst amount was increased to 2 mL. In contrast, in the photocatalytic process, MB was efficiently degraded in the presence of AgNPs under visible-light irradiation, with a pronounced decrease in absorption intensity observed within 25 min, and the degradation efficiency increased with increasing AgNPs dosage. This study highlights that green synthesis of AgNPs using orange peel pectin is a simple, economically and environmentally friendly methods for the synthesis of photocatalytically active nanoparticles.