Optimization Of Hydrochar Yield and Energy Content from Cassava and Plantain Peels Via Co-Hydrothermal Carbonisation

Abstract

Cassava (Manihot esculenta) and plantain (Musa balbisiana) peels are abundant yet underutilized sources of waste biomass that can be converted into high-quality energy resources. Hydrothermal carbonization (HTC) provides a promising solution by transforming wet biomass into hydrochar at moderate temperatures (160-250°C). This study investigates the effect of process parameters on the yield and Higher Heating Value (HHV) of hydrochar to determine the optimal conditions for maximizing yield and HHV using HTC. The yield and HHV of hydrochar were evaluated as functions of process temperature (160-200°C), residence time (60-180 minutes), and cassavato-plantain mixing ratio (30:70, 50:50, 70:30). A factorial design approach was employed to optimize these process parameters. HTC experiments were conducted in a 100 mL autoclave batch reactor containing biomass and deionized water, operated under controlled temperature and time conditions. The results revealed that hydrochar yield decreased with increasing temperature and residence time, while HHV increased with these parameters. The maximum hydrochar yield and HHV were 86.29% (wt.%) and 27.84 MJ/kg, respectively. Conversely, the minimum yield and HHV were 64.29% (wt.%) and 16.03 MJ/kg, respectively. Analysis of Variance (ANOVA) indicated that the mixing ratio had no significant effect on hydrochar yield and HHV (P > 0.05). The optimal HTC process parameters were identified as 172.53°C and 155.76 minutes, resulting in a hydrochar yield of 73.08% and HHV of 21.36 MJ/kg. These findings highlight the potential of HTC as an effective method for bioenergy production and waste management, offering a sustainable solution for disposing cassava and plantain peels.