Effects of feedstock and pyrolysis temperature of biochar on promoting hydrogen production of ethanol-type fermentation

Biochar has been shown to benefit fermentative hydrogen production. However, the influencing factors and key characteristics of its promoting function remained to be elucidated. This study investigated the effects of two cru-cial factors, feedstock and pyrolysis temperature, on the hydrogen production-promoting function of biochar in ethanol-type fermentation. The physicochemical characteristics and promoting effects of biochars prepared with five biomass wastes (coffee ground, corn stalk, Ginkgo biloba leaf, mealworm frass, and sugarcane bagasse) were determined. Sugarcane bagasse-derived biochar (SBBC) showed the best hydrogen production-promoting effect in ethanol-type fermentation. The physicochemical properties of biochar, such as pH, element composition and surface features, were significantly affected by pyrolysis temperature, but the promoting effects were not signif-icantly changed. The hydrogen production-promoting effect of biochar in ethanol-type fermentation was mainly affected by feedstock instead of pyrolysis temperature. A potential promoting mechanism was proposed that bio -char prepared at low temperature boosted the hydrogen production with redox activity, while that at high tem-perature achieved the promotion via cell growth enhancement. This study revealed the key promoting factor of biochar in ethanol-type fermentative hydrogen production, and provided novel insights for the promoting mech-anism of biochar. (c) 2021 Elsevier B.V. All rights reserved.