Role of advanced oxidation processes in lignocellulose pretreatment towards biorefinery applications: a review on emerging trends and economic considerations

Renewable energy sources have been recognized as a viable alternative to fossil fuels. Among them, lignocellulosic biomass has emerged as a promising option for producing valuable bio-products, especially employing residual or waste material due to its consistency, reliability, local availability, and carbon neutrality. However, its efficient utilization is limited by the recalcitrance of cell walls, mainly caused by two chemical compounds, hemicellulose and lignin, reducing the accessibility to cellulose. Consequently, the hemicellulose and/or lignin in the cell wall need to be removed or rearranged to increase the accessibility to cellulose through the pretreatment of lignocellulosic biomass. Among the different pretreatments, oxidative processes efficiently enhance the digestibility of cellulose in lignocellulosic biomass, breaking down the complex structure of lignocellulosic biomass and making it more accessible for subsequent enzymatic or microbial degradation. Moreover, oxidative processes improve the reaction kinetics, are versatile in treating a wide range of lignocellulosic feedstocks, and reduce the generation of waste products. Therefore, this review aims to provide a detailed overview of the properties and composition of lignocellulosic biomass, its potential, and a comprehensive analysis of oxidative pretreatments, their advancements and recently developed innovative technologies. Furthermore, the application and economic feasibility of utilizing lignocellulosic biomass and the key obstacles hindering its widespread adoption are highlighted in this review. Renewable energy sources have been recognized as a viable alternative to fossil fuels.