Diopside nanoparticles from rice husk ash: green synthesis, characterization and investigation of congo red dye removal, antibacterial properties, and Biginelli catalytic reaction (statistical approach to optimize parameters)

The technological trend toward "Wealth from Waste" is pertinent with the effective utilization of agricultural waste such as rice husk with properties such as availability, cost-effectiveness, durability, biodegradability, and environmentally friendly resources. In this article, nanodiopside concerning their wide application was synthesized using silica source from rice husk, calcium nitrate, and magnesium chloride. In this study, diopside nanoparticle was synthesized using rice husk ash obtained from agricultural waste. Then, the structure of nanodiopside was corroborated using FT-IR, EDX, TGA, FE-SEM, BET, XRD spectroscopic methods and the antibacterial properties of nanodiopside as well as its use as a nanocatalyst in Biginelli reaction and adsorbent to remove congo red dye was investigated. The experiment design method was used to optimize the Biginelli reaction conditions and to remove congo red dye. Finally, the antibacterial properties of nanodiopside were investigated. The results show that the heterogeneous diopside nanocatalyst can be reused up to 5 times. In addition to being economically and environmentally green and having good performance, nanodiopside reduces reaction time and the product has a good yield. In addition, recovery of the adsorbent shows that nanodiopside can be reused up to 4 times. Also, the study of adsorption isotherm and adsorption kinetics in optimal conditions showed that they correspond to the Langmuir and pseudo-second-order models, respectively. Furthermore, the data showed that nanodiopside has antibacterial properties.