Effects of enzymatic modification of biomass precursor on the pore structure and VOCs adsorption performance of porous carbon

This study addresses the issues of uniform pore structure and limited specific surface area in cellulose-based porous carbon materials prepared by traditional pyrolysis methods. A synergistic pore-forming strategy combining cellulase fermentation pretreatment with KOH activation is proposed to fabricate high-performance porous carbon materials and investigate their adsorption performance for butyl acetate (a typical volatile organic compound, VOC). Two biomass precursors, namely highly crystalline pure cellulose and low-crystallinity sugarcane bagasse, were selected. Pretreatment modification was conducted via cellulase fermentation, followed by KOH activation to prepare porous carbon. The effects of enzymatic treatment on biomass crystallinity, microstructure, pore structure, and adsorption performance were systematically investigated. The results indicated that the efficacy of cellulase pretreatment significantly depended on the initial crystallinity of the biomass. For highly crystalline pure cellulose (crystallinity 90%), enzymatic treatment did not markedly alter its crystallinity. However, it effectively refined the particle size and made the structure looser, thereby promoting the development of supermicropores during subsequent activation. Specifically, the supermicropore volume increased from 0.688 cm³/g to 0.989 cm³/g, and the butyl acetate adsorption capacity increased from 685.4 mg/g to 931.6 mg/g. In contrast, for low-crystallinity sugarcane bagasse, enzymatic treatment led to a fluctuating increase in crystallinity (from 52.6% to 68.9%) and introduced pores and fragmented structures on the fiber surface through a "bio-etching" mechanism. Consequently, the supermicropore volume increased from 0.768 cm³/g to 0.926 cm³/g, and the adsorption capacity increased from 756.3 mg/g to 882.9 mg/g. Multiple linear regression analysis further confirmed that supermicropore volume was the key factor enhancing butyl acetate adsorption performance.