Impact of processing parameters on the hydrothermal carbonisation of African Elemi Shell

Abstract This study investigates the valorization of the African Elemi (Canarium schweinfurthii) shell, an underutilized biomass waste, through hydrothermal carbonization (HTC) to produce high-quality hydrochar. The research aims to optimize HTC parameters for African Elemi shell conversion and characterize the resulting hydrochars physicochemical properties for potential adsorbent applications. The experimental design employed a temperature-controlled batch reactor system, processing the shells under oxygen-free conditions. Response surface methodology (RSM) with central composite design optimized key parameters: reaction temperature (180–220 °C), residence time (30–90 min), and biomass-to-water ratio (1:8–1:12). Optimal HTC conditions were 220 °C, 65.22 min, and a 1:9.06 ratio, producing hydrochar with a dry weight yield of 24.72%, an oil yield of 28.60%, and a surface area of 729.56 m 2 /g. The hydrochar exhibited favorable properties for various applications, including a high carbon content of 82.00%, low ash content of 0.88%, and surface area of 0.281 m 2 /g. This research highlights the African Elemi shell's potential for producing multifunctional hydrochar, contributing to sustainable biomass waste conversion and supporting Sustainable Development Goals (SDGs). Future research may explore hydrochars efficacy in specific applications and assess the HTC process's scalability and sustainability.