HYDROTHERMAL CARBONIZATION COUPLED WITH ULTRASOUND ASSISTED EXTRACTION FOR RECOVERY OF PHENOLIC COMPOUNDS

摘要

Since the world average population is expected to grow during the next years, also coffee production and consumption is going to increase as well. This makes necessary to find a valuable way to valorize the residues generated by instant coffee production called exhausted or spent coffee ground (SCG). SCG is a wet organic material with lignocellulosic structure (Silva et al. 1998), containing a high amount of valuable compounds, such as polysaccharides, proteins, lipids, aliphatic acids, alkaloids, tannins, polyphenols (Campos-Vega et al. 2015) and high calorific value. Thus aims to find a proper way to treat SCG to produce value-added products and/or use the remaining solid for a suitable application, depending on the specific scenario. Hydrothermal carbonization (HTC) is a promising technology for the treatment of wet feedstock (up to 80 wt.%), at temperatures between 180 to 260 °C during a reaction time between 30 min to several hours. The main product of HTC is hydrochar, and a co-product called process water (PW). Ultrasound assisted extraction (UAE) is an eco-friendly technology suitable for the extraction of valuable compounds in the SCG, such as phenols and tannins. The target of this study is the production of hydrochar and the quantification of the total phenolic content (TPC) (mg GAE/g dry solid) after HTC and UAE.