Controlled Production of Monodisperse Plant-Mediated AgNP Catalysts Using Microwave Chemistry: A Desirability-Function-Based Multiple-Response Optimization Approach

Abstract

This study introduces a new straightforward strategy for screening the formation of catalytically active and monodisperse silver nanoparticles (AgNPs) using Epilobium parviflorum green tea extract and microwave technology. The method facilitates from multivariate statistical analysis for the optimization of the reaction conditions at which the produced AgNPs exhibit the best catalytic response for the model reduction reaction of 4-nitrophenol (4-NP). A five-level two-factor Central Composite (CCD) design of experiments (DOE) together with a response surface methodology (RSM) based desirability function approach was applied for the optimization of two variables, which are microwave exposure time and amount of silver nitrate, to obtain the desired monodisperse AgNPs displaying the best catalytic activity with the green and biogenic synthesis methods. The overall desirability of 82.2% for the measure of dispersity function of AgNPs (psi) and the first-order-reaction rate constants (kapp) were obtained. The nanospheres with the TEM mean diameter of 19.10 +/- 2.06 nm were successfully synthesized in the optimized conditions: 15 min of microwave exposure time and 4 mL of AgNO3 (10 mM) at 100 degrees C with a laboratory-grade microwave reactor and the formed nanoparticles were fully characterized. Verification experiments (psi=3.546x105and kapp=0.0293 s(-1)) confirmed the validity of the predicted model (psi=3.567x105and kapp=0.0291s(-1)) (p<0.05).