Biogenic silver/zinc oxide-carboxymethyl cellulose nanocomposites with enhanced photocatalytic and antimicrobial activities for environmental remediation.

The development of a green methodology for the synthesis of silver/zinc/carboxymethyl cellulose (Ag/ZnO/CMC) nanocomposites using cinnamon extract as a reducing and stabilizing agent is reported herein. The innovation aspect of this research is the incorporation of biogenic Ag and Zn nanoparticles into the biodegradable CMC polymer matrix, resulting in the development of a versatile nanocomposite material with high antimicrobial and photocatalytic activities under visible light illumination. The nanocomposites were characterized by UV-Vis, FTIR, XRD, SEM, TEM, EDX, XPS, BET, and TPD techniques, confirming the mesoporous nature with Ag, AgCl, and ZnO crystals being uniformly distributed in the polymer matrix. The Ag/ZnO/CMC nanocomposite demonstrated exceptional antibacterial effects on Gram-positive and Gram-negative bacterial strains with an inhibition zone between 30.0 ± 0.8 and 36.0 ± 1.2 mm, which was higher than that achieved by the azithromycin antibiotic on various tested strains. The Ag/ZnO/CMC NC also showed broad-spectrum antibacterial activity, with MIC values of 3.125, 6.25, 6.25, and 12.5 µg mL-1 against B. subtilis, K. pneumoniae, S. aureus, and S. typhimurium, respectively. In addition, the nanocomposite attained 99.33 ± 1.00% photocatalytic degradation of the Crystal violet dye in 180 minutes under visible light illumination. From the kinetic study, an excellent match was found between the experimental data and the Langmuir-Hinshelwood kinetic model (R 2 = 0.972). In addition, based on the analysis of thermodynamics, it was discovered that the reaction is spontaneous and endothermic. The nanocomposite remained stable with a degradation efficiency of over 91% after five rounds of recycling. The above results reveal that the nanocomposite is highly stable and recyclable. This research study is a sustainable platform for future eco-friendly multifunctional nanocomposites that will help in environmental remediation, wastewater purification, and antimicrobial protection.