Green solvent-assisted hydrothermal conversion of biomass waste into bio-oil under pressurized conditions

This study investigates the effects of hydrothermal treatment combined with acetic acid on the distribution of products in bio-oil obtained from grape seed pyrolysis. A Box-Behnken experimental design was employed, varying pH (2.0, 4.5, and 7.0), temperature (160 , 180, and 200 degrees C), and flow rate (1, 2, and 3 mL<middle dot>min (-1) ) to determine the hydrothermal treatment's impact on product distribution. A pyrolysis-gas chromatography/mass spectrometry system was used to perform pyrolysis of hydrotreated biomass and analyze product composition. Optimized models revealed that different process conditions favored distinct compound types. For example, increased temperature and decreased pH and flow rates enhanced hydrocarbon presence, achieving 32.3% abundance compared to 1.15% in untreated biomass. Conversely, oxygenated compounds such as ketones and aldehydes were optimized at high flow rates, milder temperatures, and low/high pH, reaching 66.7% abundance compared to 42.6% for untreated biomass. This work stands out for the green solvent-assisted hydrothermal processing of grape seeds, adding value to a low-applicability agro-industrial residue. It reduces process toxicity and results in a significant increase in the presence of hydrocarbons in the bio-oil, representing a promising approach for converting biomass waste into valuable bioproducts with potential applications in the chemical and fuel industry. It also demonstrates the potential scalability of this technology. These innovative aspects are relevant to waste management and the search for sustainable sources of energy and chemicals.