Green synthesis of rice straw-derived silica nanoparticles by hydrothermal process for antimicrobial properties and effective degradation of dyes

Rice straw is considered a major agricultural waste that has become a major threat to the environment. However, waste valorization of rice straws is a major challenge for the whole world. Therefore, this research aimed to utilize the different varieties of rice straw including Parmal rice straw (PRS), and Basmati rice straw (BRS) for the synthesis of silica nanoparticles (SiNPs) using hydrothermal autoclave method to precisely modify the particle size, and distribution, morphology and purity. This method uses water as a reaction medium under high temperature and pressure, which results in energy savings and reduced chemical waste compared to traditional methods. Furthermore, SiNPs were characterized using different analytical techniques. SEM showed the rough, compact, and highly ordered surface for both samples, while the SNP exhibited irregular shapes and rough surfaces. Rice straw powder revealed major functional groups at 787 cm⁻¹, 1461 cm⁻¹, and 2919.10 cm⁻¹. BRS and PRS showed thermal stability up to 380 ℃ and 250 ℃, respectively. The particle size of BRS and PRS were found to be 112.47±1.23 nm and 114.98±1.23 nm, respectively. PRS-SiNPs showed the effective dye reduction ability for anthraquinone (96.79%± 0.39) and alizarin yellow (92.63%± 0.17) in 30 min. Additionally, the SiNPs exhibited potential bactericidal activity against Staphylococcus aureus and Escherichia coli in terms of zone of inhibition. Overall, the SiNPs synthesized from PRS demonstrated superior photocatalytic efficiency in the reduction of dyes compared to those synthesized from BRS.