Plasmonic silver nanoparticles decorated surface functionalized Zirconium doped quantum dots - for enhanced photochemical synthesis of lactic acid esters

Abstract

Lactic acid, or 2-hydroxypropionic acid (CAS 50-21-5), a natural organic acid immensely engaged in agricultural industry, pharmacy, garment and chemical industry with a long history of practice. Lactic acid generated in fermentation necessitates an extra purification step that must be cost-effective. A green and energy derivatization of lactic acid into corresponding esters was carried out under photocatalytic conditions in this study to render them volatile for distillation separation. Esterification reaction was carried out under low energy photocatalytic system under solvent free conditions using a range of Zirconium impregnated-activated Titanium dioxide photocatalysts (1-0.005Ag/1.9-4.4%S-2.5-12.5%Zr@TO). Both physical and chemical events in the reaction grid have been studied and thermodynamic and kinetic parameters have been established expending pseudo-homogeneous (PH), Eley-Rideal (ER) and Langmuir-Hinshelwood-Haugen-Watson (LHHW) models and the different adsorption of components were proposed to fit the intrinsic kinetic data. Reaction mechanism for the process have been proposed based on the kinetic modelling results as well as FT-IR, TGA, Ammonia-TPD and photo-Electrochemical characterizations, as well as radical trapping tests, were also used to effectively support the reaction mechanism. The findings will be beneficial in the design of industrial photo-reactors for low temperature ester synthesis strategies.