Unlocking Biomass Valorization Through Cavitation-Assisted Pretreatment

Depletion of fossil fuels has prompted the need for the development of sustainable methods for deriving value-added chemicals from sustainable sources of biomass. Currently, there are significant problems associated with the conventional approach, mainly in terms of slow rates of processing and higher associated costs of production. Cavitation-assisted pretreatment gives a favorable alternative approach for enhancing process efficacy under milder operating conditions. The present work reviews the application of cavitation, viz. acoustic and hydrodynamic cavitation, for the process intensification of the conversion route of biomass to value-added chemicals—mainly the pretreatment to separate different components of biomass as lignin, hemicellulose and cellulose. The work elucidates the fundamental principles and chemistry involved in this approach followed by the effect of different geometric and operating parameters on conversion. The work also brings out scale-up issues and possible work required to overcome these problems. It has been demonstrated that cavitation offers effective ways for disrupting the complex lignocellulosic structure, as well as a robust chemical route for converting biomass into a value-added product. It is also shown that ultrasound, when coupled with green solvents, effectively fractionates biomass components, facilitating thermochemical and biochemical conversion pathways. Product yield and composition are also shown to be highly influenced by process variables such as the frequency, power density, temperature, and solvent selection. Overall, the work brings out the superiority of cavitation as compared to traditional approaches, mainly in terms of faster reaction kinetics and less waste generation.