Eco-Friendly Silver-Diatomite Nanocomposite Derived from Soybean Stalk Waste for Sustainable Water Purification: Antibacterial and Photocatalytic Properties

Abstract The current supply of clean water is not keeping pace with the growing global population’s needs. This situation necessitates the reuse of freshwater through treatment for antibacterial and dye removal. This study developed a green synthesis technique to produce a silver nanoparticle-diatomite (AgNP-D) nanocomposite for antibacterial applications against E. coli and S. aureus , as well as for the photodegradation of methylene blue (MB). Silver nanoparticles (AgNPs) were synthesized using soybean stalk extract and impregnated into the surface and pores of diatomite, forming the AgNP-D nanocomposite. The nanocomposite was characterized using UV-Visible Spectroscopy, FTIR Spectroscopy, Particle Size Analysis, and X-Ray Diffraction (XRD). UV-Visible analysis confirmed the characteristic peak of AgNPs at 446 nm. Particle size analysis indicated nanoparticle sizes in the range of 24.4-78.8 nm. The impregnation of AgNPs into the diatomite structure was confirmed by FTIR and XRD, with characteristic 2-theta values for AgNPs at 37.88°(111), 44.16°(200), 64.24°(220), and 77.34°(311). Antibacterial testing demonstrated the effectiveness of the AgNP-D nanocomposite in inhibiting bacterial growth, with minimum inhibitory concentration (MIC) values of 256 μg/mL for E. coli and >256 μg/mL for S. aureus . The photodegradation process successfully degraded 99.98% of methylene blue (100 ppm) to colorless leucomethylene blue within one minute.