Green synthesis of potassium silicate nanoparticles from biomass ashes and their antimicrobial potential

Biogenic potassium silicate (K2SiO3) NPs were synthesized from the biomasses of walnut shell (w-K2Si), pinewood stem (p-K2SiO3), and sugarcane bagasse (s-K2SiO3) by ambient fiery and KOH-assisted thermal process. The crystallite size (D) of w-K2SiO3, p-K2SiO3, and s-K2SiO3 NPs were determined to be 73 nm, 53 nm and 47 nm using Debye-Scherrer's formula. The varied strain of all samples was observed in the 0.284 to 0.301 range. Microstructure showed the cubical geometry with an irregular grain size of K2SiO3 NPs, while the SAED pattern confirmed the polycrystalline nature. The Eg of w-K2SiO3, p-K2SiO3, and s-K2SiO3 NPs was determined from Tauc's plot to be 3.66 eV, 3.75 eV, and 3.78 eV, which are closely matched to be 3.78 eV, 3.88 eV, and 3.79 eV estimated from the XPS core-level analysis. The antibacterial activity of w-K2SiO3, p-K2SiO3, and s-K2SiO3 NPs was investigated against E. coli and S. aureus bacteria. Compared to K2SiO3 NPs, the s-K2SiO3 were found to be highly toxic against E. coli and S. aureus and completely inhibited the growth of both organisms within 6 h. The findings represent the novel low-cost development of K2SiO3 NPs with potent antibacterial activities.