Recent advances in hydrodynamic cavitation-based pretreatments of lignocellulosic biomass for valorization

[Display omitted] •High lignin removals (25%–77.4%) of various LCB can be achieved by HC.•HC can effectively combine with common methods (e.g., alkali, acid, and enzyme).•Secondary effect (heating and viscosity/size reduction) of HC is vital for economy.•Applying the HC pretreatment to full-scale fermentations of LCB is possible. Recently, the hydrodynamic cavitation (HC)-based pretreatment has shown high effectiveness in laboratories and even in industrial productions for conversion of lignocellulosic biomass (LCB) into value-added products. The pretreatment capability derives from the extraordinary conditions of pressures at ∼500 bar, local hotspots with ∼5000 K, and oxidation (hydroxyl radicals) created by HC at room conditions. To promote this emerging technology, the present review summarizes the recent advances in the HC-based pretreatment of LCB. The principle of HC including the sonochemical effect and hydrodynamic cavitation reactor is introduced. The effectiveness of HC on the delignification of LCB as well as subsequent fermentation, paper production, and other applications is evaluated. Several key operational factors (i.e., reaction environment, duration, and feedstock characteristics) in HC pretreatments are discussed. The enhancement mechanism of HC including physical and chemical effects is analyzed. Finally, the perspectives on future research on the HC-based pretreatment technology are highlighted.