Potato peel waste-derived carbon-based solid acid for the esterification of oleic acid to biodiesel

Abstract

Bio-waste valorization to generate carbon-based solid acid catalysts for biodiesel production from the low-grade, highly acidic feedstocks has been a research hot spot over the last decade. In this study, an abundant bio-waste from the household kitchens, restaurants, and food processing industries, potato peel (PP), was adopted as a raw material for the production of a solid acid catalyst (SO 3 H-PPAC). Firstly, PP was mixed with ZnCl 2 and activated at 450 °C for 1 h to obtain a porous carbon material (PPAC), which was subsequently sulfonated via concentrated sulfuric acid treatment. Various physicochemical techniques, such as XRD, N 2 physisorption measurements, FTIR spectroscopy, and high-resolution transmission electron microscopy (HR-TEM), were used to study the structural properties of the prepared materials. The catalytic behavior of the catalyst was tested in the acid-catalyzed esterification of oleic acid with methanol for biodiesel production. The combination of the high surface area of 827.7 m 2 / g and high concentration of acidic active sites of 1.6 mmol/g led to a high oleic acid conversion efficiency of 97.2% at 5 wt.% SO 3 H-PPAC, methanol/oleic acid molar ratio of 12:1 at 80 °C after 2.5 h. Moreover, the kinetic results unveiled that the esterification reaction obeyed the pseudo-first-order kinetic model, with an activation energy of 32.9 kJ/mol. Importantly, SO 3 H-PPAC has satisfying recyclable features and could maintain ∼ 70 % of its initial catalytic performance in the 5 th catalytic run. • Sulfonated carbon catalyst was synthesized from potato peel by ZnCl 2 activation and sulfonation. • The obtained catalyst exhibited high surface area of 827.7 m 2 g -1 . • Synthesized catalyst used in oleic esterification acid and afforded a high conversion of 97.2%. • The catalyst maintained ∼ 70 % of its initial catalytic performance in the 5 th catalytic run.