Production and Characterization of Biochar and Liquid Product from Slow Pyrolysis of Durian Peel

Abstract

Durian peel is a type of biomass derived from agricultural residues, which are found in abundant in Thailand. This study aims to investigate the thermal and chemical properties of three indigenous durian peels, namely Monthong (MDP), Puangmanee (PDP), and Bacho (BDP), as well as the characteristics of biochar and pyrolysis liquid derived from slow pyrolysis of the durian peel. MDP had the greatest volatile matter and fixed carbon content, with 73.97 and 18.43 wt.%, respectively. The central composite design was utilized to optimize the conditions of three independent variables, namely pyrolysis temperature, cooling temperature, and holding time. Analysis of variance revealed that only pyrolysis temperature had a significant effect on biochar and pyrolysis liquid yields. The biochar and pyrolysis liquid yields fit by a second-order polynomial model agreed well with experimental results. As the pyrolysis temperature increased, the solid product yield decreased, while the pyrolysis liquid yield increased. The highest biochar and pyrolysis liquid yields were 56.11% and 38.53% that derive at 300 and 600 °C of pyrolysis temperature, respectively. The validation of both prediction models showed over 96% agreement. Biochar of high heating value (26.55 MJ/kg) was obtained at 600 °C pyrolysis temperature and 30 min holding time. According to the Van Krevelen plot, the molar ratios of the H/C and O/C of the biochar obtained at 600 °C of pyrolysis temperatures were similar to coal material. The high-quality biochar was of carbon storage class 4 according to the IBI classification; and the characteristics of pyrolysis liquid met community product standards of Thailand. An economic analysis was performed to assess the feasibility of converting 60 tons/year of durian peel into biochar and pyrolysis liquid. An internal project rate of return (IRR) of 25.91% with a payback period of 1.58 years was estimated. The findings of this study indicate the economic viability of immediately deploying large-scale pyrolysis utilizing a waste stream from agriculture