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Prior information on the pyrolysis product behaviour of biomass components-cellulose, hemicellulose and lignin is critical in the selection of feedstock as components have a significant influence on the pyrolysis products yield. In this study, the effect of biomass components on the yield of slow pyrolysis products (char, bio-oil and syngas) is investigated using a validated ASPEN Plus® model. The model is simulated at a temperature of 450 °C, a heating rate of 10 °C/min and a solid residence time of 30 min. The results indicated that at the given conditions, lignin contributed 2.4 and 2.5 times more char yield than cellulose and hemicellulose. The hemicellulose contributed 1.33 times more syngas yield than lignin while the cellulose and hemicellulose contributed 8.67 times more bio-oil yield than lignin. Moreover, the cost involved in the production of char using lignin (110 $/ton) is significantly economical than using cellulose (285 $/ton) and hemicellulose (296 $/ton). The net CO2 emission of lignin pyrolysis is 4.14 times lower than cellulose pyrolysis and 3.94 times lower than hemicellulose pyrolysis. It can be concluded that lignin pyrolysis is more advantageous than cellulose and hemicellulose pyrolysis. In the selection of feedstock for the slow pyrolysis, the feedstock with more lignin content is preferred. Graphical abstract

Considering the global issue of vegetable wastes generation and its impact on the environment and resources, this study evaluated the conversion of four largely produced vegetable wastes (cauliflower, cabbage, banana peels and corn cob residues) into biochar. Each waste was tested individually and as a combined blend to assess feedstock influences on biochar properties. In addition, various pyrolysis temperatures ranging from 300 °C to 600 °C and two particle size fractions (less than 75 µm, 75–125 µm) were considered. Biochars were characterized for various properties that can influence the biochars’ effectiveness as a soil amendment. It was found that pyrolysis temperature was the most dominant factor on biochar properties, but that individual feedstocks produced biochars with different characteristics. The biochars had characteristics that varied as follows: pH 7.2–11.6, ECE 0.15–1.00 mS cm−1, CEC 17–cmolc kg−1 and ζ-potential − 0.24 to − 43 mV. Based on optimal values of these parameters from the literature, cauliflower and banana peels were determined to be the best feedstocks, though mixed vegetable waste also produced good characteristics. The optimum temperature for pyrolysis was around 400 °C, but differed slightly (300–500 °C) depending on the distinct feedstock. However, smaller particle size of biochar application was always optimal. Biochar yields were in the range of 20–30% at this temperature range, except for corn cobs which were higher. This study demonstrates that pyrolysis of dried vegetable wastes is a suitable waste valorization approach to produce biochar with good agricultural properties.