Experimental Intensification and Modeling of Solid–Liquid Extraction of Polyphenols From Rice Husk Waste Using Organic Solvents

Abstract

In the present study, the experimental intensification and modeling of the extraction process of antioxidants from rice husks using different organic solvents (ethanol, methanol, and acetone, and their mixtures with water) were analyzed and discussed. The best experimental extraction conditions to recover polyphenols from rice husks were identified, and the extraction kinetic data were modeled using the mechanistic and pseudo–second‐order models. The experimental results showed that the solvent‐based extraction of polyphenols from rice husks was endothermic where the ethanol and methanol offered the best separation performance. The polyphenol extraction process using ethanol and acetone was mainly influenced by the percentage of water contained in the solvent mixture used as separation medium, whereas the extraction temperature significantly affected the polyphenol extraction with methanol. The rice husk‐based extracts obtained with methanol and ethanol showed the highest total content of polyphenols (66.72 and 60.68 of gallic acid equivalent/g of biomass) and antioxidant capacity (71.93% and 72.02% 2,2‐diphenyl‐1‐picrylhydrazyl [DPPH] inhibition). The mechanistic model offered the best performance to describe the experimental polyphenol extraction, and its results were used to discuss and analyze the mass transfer parameters associated with the intraparticle diffusion of this extraction process. These results contribute to the valorization of rice husk residues as a potential feedstock to be incorporated in the biorefinery context for obtaining value‐added products.