MTMS-modified cellulose cryogels derived from licorice (Glycyrrhiza uralensis Fisch.) Residue: Biomass materials fabrication and oil adsorption potential

A sustainable oil-adsorbing cryogel based on Licorice (Glycyrrhiza uralensis Fisch.) residues (LR) has been proposed. Due to their high cellulose content, licorice residues offer a valuable renewable resource for fabricating effective porous adsorbents. Cellulose was dissolved and regenerated from LR to form cryogels, which were then modified via chemical vapor deposition (CVD) using methyltrimethoxysilane (MTMS). Silanol groups were successfully incorporated into the cryogel structure, and MTMS treatment established a siloxane network characterized by Si–O–Si and Si–CH₃ bonds, enhancing the material's hydrophobicity. The resulting cryogels exhibited mesoporous structures, with BET analysis revealing a gradual decrease in specific surface area and a non-linear change in pore volume and pore size depending on MTMS deposition time. Excessive deposition led to partial pore collapse and reduced accessibility due to silanol condensation within the cellulose matrix. Among all samples, the cryogel treated for 16 h exhibited the most favorable balance between porosity and surface modification, achieving the highest oil adsorption capacity of 13.21–13.31 g·g⁻¹ . These findings suggest that LR-based cryogels, when optimized for hydrophobic modification, can serve as low-cost, eco-friendly adsorbents for oil spill recovery and wastewater treatment applications.