Improved Enzymatic Hydrolysis of Corn Stover by Photonanocatalyst-Aided (MSPNA) Ammonia Pretreatment

Various pretreatment methods using aqueous ammonia have been investigated as a promising method to enhance the enzymatic digestibility and fermentability of lignocellulosic biomass. However, one of the main challenges was high chemical input; thus pretreatment required more energy for ammonia recovery. In this study, pretreatment method for corn stover using aqueous ammonia assisted by photocatalysis was investigated to reduce ammonia input and to improve the enzymatic digestibility of corn stover.

A new nanomaterial with photocatalytic activity and aqueous ammonia were used. This specially-designed functional nanocatalyst (TiO2 in SiO2 shell) is highly effective for degradation of lignins because TiO₂-nanocatalysts under UV irradiation generate hydroxyl free radicals and the action of hydroxyl radicals enhance lignin hydrolysis in pretreatment, which leads to improved digestibility of the biomass. Compare to aqueous ammonia pretreatment without photocatalysis, MSPNA ammonia pretreatment significantly enhanced lignin removal (up to 25%) and enzymatic digestibility (~30%) with 15 FPU/g glucan of enzyme loading.

In this paper, various pretreatment conditions such as TiO₂ loading, ammonia concentration, reaction time, and reaction temperature were explored. Enzyme digestibility and fermentation test results will also be presented.