Modeling and experimental quantification of physicochemical, structural, and rheological synergies for enhanced enzymatic hydrolysis of agro-industrial waste

This work investigates how the physicochemical, structural, and rheological characteristics of lignocellulosic agro-industrial waste (AIW) impact its delignification and hydrolysis processes for bioethanol production, using detailed characterization at various solid loadings under continuous shear. An analytical model is also developed to quantify the shear stress characteristics of the substrate suspensions using three constituent polymers and their physicochemical properties. Rheological studies reveal that the presence of lignin outside the holocellulose core increases suspension viscosity by 6–10 times. Additionally, higher solid loadings further elevate viscosity, resulting in a 14–61 % reduction in fermentable sugar yield. Interestingly, the hydrophilic hemicellulose outside the cellulose core reduces the viscosity of holocellulose by 10–15 % compared to cellulose. The proposed model predicts that the intra- and inter-molecular interactions of the three constituent polymers in the AIW as well as external factors, such as particle size, surface roughness, degree of polymerization, and crystallinity, significantly influence the shear stress of the lignocellulosic suspension. These results support the development of innovative pretreatment strategies that can enhance fermentable sugar yields by 25–101 % during enzymatic hydrolysis. Such strategies may also help reduce shear stress and viscosity in lignocellulosic slurries, improving the efficiency of industrial bioreactors.