Selective Phenolics Recovery from Aqueous Residues of Pyrolysis Oil through Computationally Designed Green Solvent

Abstract

Leveraging advanced computational techniques, this study introduces an innovative hybrid computational-experimental approach for the recovery of hydroquinone and p-benzoquinone from the aqueous residue of pyrolysis oil derived from spent coffee grounds, offering a sustainable pathway for value-added chemicals recovery. A screw-type reactor operating within the temperature range of 450–550 °C was utilized for the conversion of spent coffee grounds into pyrolysis oil. A comprehensive characterization of the bio-oil was conducted using gas chromatography–mass spectroscopy (GC–MS) and high-performance liquid chromatography (HPLC), revealing hydroquinone and benzoquinone as the predominant phenolic compounds. Employing computer-aided molecular design (CAMD), we identified 1-propanol as an optimal green solvent for the selective extraction of quinones, offering superior process efficiency and economic viability. Notably, the extraction efficiency achieved for hydroquinone and p-benzoquinone reached up to 23.38 g/L and 14.39 g/L, respectively, from the aqueous fraction of pyrolysis oil at 550 °C, with an extraction time of 1 h. Techno-economic analysis indicated a robust rate of return of 20% and a payback period of 1.1 years for the separation process. This study underscores the critical role of a hybrid experimental-modelling approach in developing sustainable processes for the valorization of biowaste into valuable materials.