Development of a kiln emission treatment unit for the production of biochar and wood vinegar

This paper aimed to assess a kiln system with an integrated condenser using citrus branches and palm fronds residues to produce biochar and wood vinegar (WV) at pyrolysis temperatures of 350, 400, and 450 °C. The citrus branches surpassed palm fronds in producing biochar with lower electrical conductivity (0.99–2.19 dS m−1 vs. 13.43–16.23 dS m−1), ash content (7.17–17.19% vs. 24.72–30.98%), and higher carbon retention efficiency (58.8–61.6% vs. 39.0–43.6%). At 400 °C, the biochar yielded the best results for citrus branches, with 65.90% yield, pH 7.28, and 1.09 dS m−1 EC, and a yield of 0.625% and ash of 2.58% with WV, meeting soil amendment. Palm fronds' biochar required washing to achieve an EC below 4 dS m−1, and WV required a 1:15 dilution to mitigate phytotoxicity risks posed by ash content. The results revealed that using citrus branches at 400 °C yielded optimal biochar and WV for soil amendments without post-processing.