Efficient in situ saccharification of microcrystalline cellulose over immobilized cellulase on magnetic biochar in ionic liquid media

Saccharification serves as the entry point for the biomass into biorefinery schemes and plays a vital role in lignocellulose transformation towards bio-fuels and platform molecules. Herein, an efficient in situ saccharification of lignocellulose under the mediation of ionic liquid of [DMIM]DMP is reported, using a series of magnetically-separable biochars as catalyst supports with immobilized endoglucanase Cel5A. The physicochemical properties of these magnetic biochars with immobilized endoglucanase (abbreviated as MBIE) were thoroughly characterized by FTIR, TG, SEM/EDX, XRD, XPS, N2 physisorption, UV-vis and VSM. The results revealed that the endoglucanase, which functions as the catalytically active species, was immobilized on the biochar via simultaneous physical adsorption and covalent attachment. The extremely high surface area of biochar endows a high loading of endoglucanase and easy diffusion of reactant within the catalyst's framework. The zeta potential of the catalyst was - 7.06 mV, indicating its excellent stability. MBIE with immobilizing endoglucanase of 484.36 mg/g exhibited the superior performance under a biphasic system (IL/water v/v 5:1), affording a glucose yield of 932.5 mg/g. The activity of MBIE remained constant after 10 consecutive cycles via magnetic recycling. This work demonstrates an efficient in situ saccharification process catalyzed by the developed MBIE with high activity and excellent regeneration ability.