Mechanical Ball Milling as a Green Strategy for Lignocellulose Valorization: A Review

The massive CO₂ emission arising from fossil fuel combustion has exacerbated climate crises and disrupted ecological balance, driving the need for sustainable processes for the efficient utilization of renewable resources. Lignocellulose represents as a promising alternative to fossil-based feedstock, while the inherent structural recalcitrance significantly hinders its efficient conversion. Mechanical ball milling is considered as a potential strategy for lignocellulose valorization for its intensive mechanical energy to disrupt the physical architecture of lignocellulose. Currently, the existing reviews mostly focus on the application of mechanical ball milling for biomass-based materials preparation, lacking integrated discussions on the application for lignocellulose separation and depolymerization. This review emphasized the synergistic effect of the mechanochemical strategy for structural disruption and chemical activation, which includes the effective separation of lignin and cellulose and their depolymerization to obtain value-added monomers and platform chemicals. Furthermore, the potential and energy advantages of mechanical ball milling for industrial-scale applications were elaborated by comparing different mechanochemical strategies, combined with energy consumption comparison and process scaling. Finally, future perspectives on the precise optimization of mechanical ball-milling systems are proposed. This review offers promising guidance on the valorization of lignocellulosic biomass.