Conceptual Design of a Coupling Process of Hydrodynamic Cavitation and Hydrothermal Separation for Extractives and Biopolymers Extraction

Abstract

Lignocellulosic biomass is an abundant and sustainable resource for producing biopolymers, chemicals, biofuels, and high-value-added compounds. The primary refining processes, which includes pretreatment, fractionation, and separation of components, as well as structural disconnection or partial structural change, are necessary to achieve high-value utilization of lignocellulosic materials. However, conventional pretreatment processes for biomass valorization aim to obtain high yields of cellulose without concern for utilizing other components. Focusing on a single component of lignocellulose is not only a waste of resources but also causes serious environmental pollution. This study proposed a novel and efficient biomass processing concept that, for the first time, couples two key technologies (hydrodynamic cavitation and hydrothermal separation) to enable almost all the biomass to be used for a range of high-valued products, including biopolymers and extractives. The conceptual design of coupling of hydrodynamic cavitation and hydrothermal separation was then modeled and simulated to evaluate the ease of coupling in terms of component yield and overall extraction efficiency and observed how the coupling process was affected by the process parameters with an optimal overall extraction efficiency. The simulation results showed that the coupling of the HC and HTS processes had a maximum of 25.5% higher overall extraction efficiency than the single HC process and 18.2% higher efficiency than the single HTS process for woodchips. The process parameters, including HTS temperature, HTS residence time, and S/L ratio affected component yield and overall extraction efficiency. The maximum overall extraction efficiency was predicted by the statistical approach of 80.20 ± 5.04% with a regression coefficient (R-sq) of 99.33% at optimal conditions (S/L ratio 10%, HC pressure 3 bar, HC temperature 60℃, HC residence time 20 min, HTS temperature 210 ℃, HTS residence time 25 min, and HTS pressure of 19.04 bar). The coupling of hydrodynamic cavitation and hydrothermal separation showed better biomass utilization than the conventional pretreatment processes. This coupled process focuses on more utilization of biomass rather than only one yield, which will reduce the waste with minimal environmental effect and increase the potential use of biomass from different perspectives.