Sustainable preparation of multifunctional green silver nanoparticles for efficient catalytic dye degradation and bacterial inhibition.

Abstract

The rapid expansion of industrialization and the escalating threat of antimicrobial resistance are two converging challenges of the modern era, posing serious threats to both ecological balance and human well-being. Designing sustainable and affordable nanomaterials for wastewater treatment is a growing priority, especially those capable of addressing both chemical and biological pollutants. This work reports a green and sustainable approach for synthesizing silver nanoparticles (AgNPs) utilizing Citrus aurantium peels aqueous extract (CAPE) as the reducing and stabilizing agent for treating organic dye-contaminated wastewater and harmful bacteria. Unlike conventional synthesis approaches, this method employs readily available and renewable agro-waste materials, reduces environmental impact and synthesis cost, and eliminates the need for hazardous chemicals. The resulting CAPE-AgNPs were characterized using UV/Vis, TEM, SEM, EDX, FTIR, TGA, and XRD techniques, confirming their nanoscale structure and high stability. The nanoparticles effectively catalyzed the reduction of toxic dyes (e.g., methyl orange (93.7%), phenol red (97%), methylene blue (95%), and safranin O (45.4%)) using NaBH₄. The antibacterial performance of CAPE-AgNPs was evident against a range of Gram-positive and Gram-negative bacteria, with minimum inhibitory concentrations (MIC) spanning 0.41 to 0.82 g/L. The formation of a clear zone around the material indicated bacterial growth inhibition. Compared to previous studies, this work highlights the dual functionality of biosynthesized AgNPs for simultaneous chemical and microbial decontamination of water using a low-cost, green synthesis method that valorizes agro-waste.