Optimization and mechanistic kinetic model: Toward newsprint waste conversion to levulinic acid

Abstract

In this study, Box-Behnken design was employed to optimize the yield of levulinic acid from HCl pretreated (HCl-NP) and Fenton pretreated (Fenton-NP) newsprints. Experiments were performed in a 5 mL Pyrex tube batch reactor at the following conditions: 180‐200 °C of reaction temperature (T), 3.5‐4.5 h of reaction time (t), 0.1‐0.2 M of catalyst concentration ([FeCl3*6H2O]), and 20-wt% LiCl, which served as a promoter. With the optimum conditions for conversion of HCl-NP and Fenton-NP as follow: T = 200 °C, t = 3.63 and 3.50 h, and [FeCl3*6H2O]= 0.118 and 0.100 M, the predicted maximum yields of levulinic acid were 83.4 mol% and 86.4 mol%, respectively. This showed that the optimal conversion of HCl and Fenton-NP occurred at different processing conditions. A mechanistic model was developed where the experimental concentrations of cellulose, glucose, hydroxymethylfurfural, and levulinic acid were simulated to generate the model’s kinetic parameters. This provides a deeper insight into the various stages necessary to improve levulinic acid yields from newsprint wastes.