Conference Agenda

The discharge of synthetic dyes into aquatic systems represents a significant environmental challenge due to their persistence and resistance to degradation. This study investigates the sustainable valorization of avocado seed biomass through hydrothermal carbonization (HTC) for methylene blue removal from water. A Box–Behnken experimental design was applied to evaluate the effects of temperature (180–250 °C), residence time (2–8 h), and solid-to-water ratio (1:5–1:15) on adsorption performance. The results indicated that temperature was the most influential factor, with optimal conditions identified at 180 °C, 5 h, and a solid-to-water ratio of 1:15. To further enhance adsorption capacity, deep eutectic solvents (DES, choline chloride–urea) and natural deep eutectic solvents (NADES, choline chloride–thiourea) were incorporated during HTC at different molar ratios. DES treatment significantly improved dye removal, achieving the highest efficiency at a 1:2 molar ratio, while NADES showed moderate enhancement. SEM, BET, and FTIR analyses confirmed that eutectic-assisted HTC influenced surface morphology, mesoporosity, and functional group distribution. The findings demonstrate that DES-assisted hydrothermal carbonization of avocado seed represents an environmentally friendly strategy for improving hydrochar adsorption performance, contributing to biomass valorization and sustainable water treatment technologies.