Optimization of liquid smoke production from coconut shell waste via slow pyrolysis in a fixed-bed reactor using FCCD-RSM

• Liquid smoke was produced from coconut shell via electrically heated assisted pyrolysis. • Pyrolysis conditions were evaluated via response surface methodology. • Optimum production was achieved at 2.71 mm raw size, 389.3℃, and 29.5 min. Coconut shell waste poses a danger to the environment and public health. With its antimicrobial properties, pyrolysis converts organic waste into bio-oil in an electrically heated reactor. This research aims to identify the chemicals in pyrolytic coconut shell oil and optimizes the process using RSM FCCD. The pyrolysis experiment was conducted in a fixed-bed reactor heated electrically to produce pyrolytic coconut shell liquid smoke or oil. The main process parameters, such as time (5–30 min), temperature (210–410℃), and variations in coconut shell size (1–3 mm), were optimized to achieve optimal liquid smoke yield. The main features of the produced liquid smoke were investigated. The findings indicated that the yield of liquid smoke decreased with the reduction in material size and increased with the increase in time and temperature. The optimum result was found to be 46% with temperature 400℃, material size 2 mm, and heating time 30 min, indicating that the model was reliable and reproducible. FCCD-type RSM successfully predicted the interface and the importance of pyrolysis factors. Seven different chemical components were found in the liquid smoke made, including phenol, dimethoxy phenol, guaiacol, hydroxyanisole, and methoxyphenol. The outcomes of the present study could promote sustainable production method of liquid smoke while reducing carbon foot print in the food and agriculture industry.