RESUMEN
Ionic liquid based technology is promising in the pretreatment of lignocelluloses. More efforts are still being made to intensify the separation of the main components in this biomass and to inhibit biopolymer degradation, especially in the fabrication of functional materials where excellent mechanical properties are often requisite. In this study, additives with amino and/or hydroxyl groups were proposed to improve the dissolution of lignocellulosic biomass in ionic liquids and to inhibit the degradation of cellulose. Among the tested additives (i.e., urea, L-2-aminobutyric acid, DL-aminopropanol, 3-aminopropanol and ethanolamine), 3-aminopropanol showed the best performance in enhancing wheat straw dissolution and cellulose recovery in 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac). Further study revealed that this additive could also inhibit cellulose degradation in [EMIM]Ac. The interactions between the ionic liquid and additive were revealed by NMR and IR analysis. It was found that the formation of hydrogen bonds between 3-aminopropanol and [EMIM]Ac changed the interactions between ionic liquids and biomass, resulting in improved dissolution efficiency and inhibition of cellulose degradation. Optimization investigation showed that when using the 3-aminopropanol/[EMIM]Ac composite system as the solvent and pine as the raw biomass, the cellulose content in the recovered cellulose-rich material was increased from 33.3% (for the raw pine) to 66.9%. Correspondingly, the regenerated cellulose spinning in the composite system exhibited improved mechanical properties, with the elongation at break reaching 15.6% and the tensile fracture strength of 184.1 N per tex (in comparison with 9.6% for elongation at break and 99.7 N per tex for tensile fracture strength for the sample obtained in neat [EMIM]Ac).
RESUMEN
This study investigated the hydrochar-based porous carbon prepared by combining the technical route of hydrothermal carbonization (HTC) + chemical activation. The hydrochar morphology was adjusted by changing the activation reaction conditions and adding metal salts. Experiments showed that the activation of KHCO3 significantly increased the specific surface area and pore size of the hydrochar. Besides, oxygen-rich groups on the surface of the activated hydrochar interacted with heavy metal ions to achieve efficient adsorption. The activated hydrothermal carbon adsorption capacity for Pb2+ and Cd2+ ions reached 289 and 186 mg/g, respectively. The adsorption mechanism study indicated that the adsorption of Pb2+ and Cd2+ was related to electrostatic attraction, ion exchange, and complexation reactions. The "HTC + chemical activation" technology was environmentally friendly and effectively implemented antibiotic residues. Carbon materials with high adsorption capacity can be prepared so that biomass resources can be utilized with excessive value, as a consequence presenting technical assistance for the comprehensive disposal of organic waste in the pharmaceutical industry and establishing a green and clean production system.
