Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two addedvalue products. The seeds were hydrothermally carbonized at a temperature range of 150-250 & DEG;C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg- 1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 & DEG;C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 & DEG;C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 & mu;g mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 & DEG;C, whereas furans and aldehydes were primarily formed at 150 & DEG;C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 & DEG;C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

Automated summary

In the framework of circular bio-economy, waste loquat seeds were utilized to produce two added-value products through hydrothermal carbonization. The hydrochars obtained at 250°C and 6 h exhibited optimum higher heating value and ash content for energy-related applications, while the aqueous phase obtained at the same conditions showed strong antioxidant activity. Different temperature and residence time conditions favored the production of specific compounds. Both added-value products were obtained simultaneously at the same optimum hydrothermal carbonization conditions.