Solid-liquid mass transfer characteristics and mechanism of alkali-soluble heteropolysaccharides from hemp stalk

Establishment of a precise control model is conducive to efficient extraction of heteropolysaccharides (Hete) from lignocellulose biomass during alkali treatment process. Thus, this work focused on studying the dissolution behaviors of heteropolysaccharides from hemp stalk under different extraction conditions and developing a precise model to describe its solid-liquid mass transfer process. The results showed that under the optimal liquid to material ratio condition, alkali concentration and extraction time were the main factors affecting the extraction efficiency, followed by temperature and hydrogen peroxide dosage. Meanwhile, the influence of the flow state of lye and the particle size of hemp stalk cannot be also ignored. The established mass transfer models showed that the diffusion activation energy of heteropolysaccharides during laminar- and turbulent-flow states were 1.1044 and 1.1015 kJ/mol, respectively, which totally proved that the dissolution of heteropolysaccharide under alkaline condition was a solid-liquid diffusion-dominated mass transfer process. The internal and external verification results showed that the correlation and robustness of laminar- and turbulent-type diffusion models were very good and suitable for controlling the dissolution of heteropolysaccharides from hemp stalk or similar plants.