Hydrothermal conversion of grape pomace: Detailed characterization of obtained hydrochar and liquid phase

• Grape pomace was hydrothermally carbonized at 180, 200 and 220 °C and characterized.
• Major structural alterations of obtained process streams were substantiated.
• HTC temperatures were correlated to structural changes by multivariate analysis.
• Hydrochar obtained at 220 °C exhibited significant energetic potential and porosity.
• Antioxidant activity of process waters was associated with total anthocyanins.

In this study, carbonization products of grape pomace (hydrochar and process water) have been thoroughly characterized in order to assess its fuel properties, physico-chemical composition and to optimize its production. The obtained detailed insight into transformations of the biomass during hydrothermal conversion between 180–220 °C revealed that the hydrochar obtained at 220 °C exhibits a considerable energetic potential, increased porosity and re-adsorption abbility. Hydrothermally induced structural changes in the obtained hydrochars were unveiled by thermal and morphology analysis, FTIR and NIR spectroscopy. Temperature increment caused a decrease in antioxidative capacity, anthocyanin and organic acid content in process water and simultaneous increase in total phenolic and individual organic components content. The overall effect of the reaction temperature on products characteristics was assessed by multivariate data analysis. Obtained results substantiated the suitability of hydrothermal conversion of grape pomace into highly valuable fuels and versatile products.

Figure optionsDownload as PowerPoint slide