Peach Seeds Pyrolysis Integrated into a Zero Waste Biorefinery: an Experimental Study

Abstract

This study reports results of an experimental investigation of peach seeds for vegetable oils and biofuel production. Dry peach seeds have undergone hexane extraction for the recovery of oils/lipids and then pyrolyzed in a laboratory reactor. Pyrolysis parametric investigation was carried out to explore the effect of temperature, heating rate, and carrier gas flow on products’ yield. Energetic characterization of products was performed to assess them as biofuels, compared also with biofuels derived from other feedstocks. Results showed that pyrolysis temperature and heating rate played important role on yield and the composition of pyrolysis products. Extraction of oils/lipids reached 38.6 % wt., while pyrolysis gas, oil, and char yielded as 10–25, 37–50, and 10–20 % wt., respectively, at different pyrolysis conditions. Pyrolysis gas, bio-oil, and biochar HHVs estimated values were in the ranges of 10.5–28.5, 29–33, and 19.5–22.2 MJ/kg, respectively, all higher than that of lignite (19.3 MJ/kg). Sulfur content was not traceable in both solid and liquid products, while nitrogen content did not exceed 8.5% wt. The degree of linear association between pyrolysis parameters/variables and products’ yields and HHV was examined using the Pearson correlation coefficient. The results revealed that the cascade biorefinery approach applied for the valorization of peach seeds to produce oil/lipids and fuels, by sequential processing via hexane extraction and pyrolysis, can reach increased material and energy efficiencies varying from 73.5 to 93.7 % wt. and from 30.4 to 50 %, respectively. It can also increase the environmental and economic benefit of the agri-food sector while providing a green, closed loop, circular bioeconomy industrial practice.