High-Performance Hydrogel Adsorbent Based on Cellulose, Hemicellulose, and Lignin for Copper(II) Ion Removal

Cellulose, hemicellulose, and lignin are three kinds of biopolymer in lignocellulosic biomass, and the utilization of the three biopolymers to synthesize hydrogel adsorbent could protect the environment and enhance the economic value of the biomass. A novel hydrogel adsorbent was prepared using cellulose, lignin, and hemicellulose of wheat straw by a one-pot method, and the adsorbent showed excellent adsorption performance for copper(II) ions. Scanning electron microscopy and Fourier transform infrared spectroscopy analysis showed that the prepared straw-biopolymer-based hydrogel had porous structure, and cellulose fibrils had crosslinked with lignin and hemicellulose by poly(acrylic acid) chains. The effects of contact time, initial concentration, and temperature on the copper(II) ion removal using the prepared hydrogels were investigated, and the obtained results indicated that the adsorption kinetics conformed to the pseudo-second-order and Elovich equation models and the adsorption isotherm was in accord with the Freundlich model. The adsorption thermodynamics study indicated that the adsorption process was spontaneous and accompanied by heat. X-ray photoelectron spectroscopy analysis revealed that the adsorption behavior resulted from ion exchange. The prepared hydrogel based on cellulose, hemicellulose, and lignin could be used for water treatment and soil remediation because of its high performances of excellent heavy metal ion removal and water retention.

Rheological modification of partially oxidised cellulose nanofibril gels with inorganic clays

This study aimed to quantify the influence of clays and partially oxidised cellulose nanofibrils (OCNF) on gelation as well as characterise their physical and chemical interactions. Mixtures of Laponite and montmorillonite clays with OCNF form shear-thinning gels that are more viscous across the entire shear range than OCNF on its own. Viscosity and other rheological properties can be fine-tuned using different types of clay at different concentrations (0.5–2 wt%). Laponite particles are an order of magnitude smaller than those of montmorillonite (radii of 150 Å compared to 2000 Å) and are therefore able to facilitate networking of the cellulose fibrils, resulting in stronger effects on rheological properties including greater viscosity. This work presents a mechanism for modifying rheological properties using renewable and environmentally-friendly nanocellulose and clays which could be used in a variety of industrial products including home and personal care formulations.

Assembling Native Elementary Cellulose Nanofibrils via a Dynamic and Spatially Confined Functionalization

Selective surface modification of bio-sourced colloids affords effective fractionation and functionalization of polysaccharide-based nanomaterials, as shown by the classic TEMPO-mediated oxidation. However, such route leads to changes of the native surface chemistry, affecting interparticle interactions and limiting the full exploitation of the supermaterial properties associated with such nanomaterial assemblies. Here we introduce a methodology to extract elementary cellulose fibrils by treatment of biomass with N-succinylimidazole, achieving spatially confined (92% regioselectivity towards primary C6-OH) and dynamic surface functionalization, as elucidated by nuclear magnetic resonance, infrared spectroscopy, and gel permeation chromatography. No polymer degradation or crosslinking nor changes in crystallinity occur under the mild conditions of the process yielding elementary fibrils. The structure of the fibrils was validated by cross-corelating solid-state NMR, chromatographic analysis, and atomic force microscopy imaging. We demonstrate the fully reversible nature of the dynamic modification, which offers a significant opportunity for the reconstitution of the interfaces back to the native states, chemically and structurally. Consequently, access to 3D structuring of native elementary cellulose I fibrils is made possible, reproducing the supramolecular features of the native cellulosic supermaterials. Overall, we propose the reversible and regioselective surface succinylation as a suitable route to overcome current limitations in the production of cellulose nanomaterials, which is required to unlock the full potential of cellulose as a sustainable building block.<br>

Assembling Native Elementary Cellulose Nanofibrils via a Dynamic and Spatially Confined Functionalization

Selective surface modification of bio-sourced colloids affords effective fractionation and functionalization of polysaccharide-based nanomaterials, as shown by the classic TEMPO-mediated oxidation. However, such route leads to changes of the native surface chemistry, affecting interparticle interactions and limiting the full exploitation of the supermaterial properties associated with such nanomaterial assemblies. Here we introduce a methodology to extract elementary cellulose fibrils by treatment of biomass with N-succinylimidazole, achieving spatially confined (92% regioselectivity towards primary C6-OH) and dynamic surface functionalization, as elucidated by nuclear magnetic resonance, infrared spectroscopy, and gel permeation chromatography. No polymer degradation or crosslinking nor changes in crystallinity occur under the mild conditions of the process yielding elementary fibrils. The structure of the fibrils was validated by cross-corelating solid-state NMR, chromatographic analysis, and atomic force microscopy imaging. We demonstrate the fully reversible nature of the dynamic modification, which offers a significant opportunity for the reconstitution of the interfaces back to the native states, chemically and structurally. Consequently, access to 3D structuring of native elementary cellulose I fibrils is made possible, reproducing the supramolecular features of the native cellulosic supermaterials. Overall, we propose the reversible and regioselective surface succinylation as a suitable route to overcome current limitations in the production of cellulose nanomaterials, which is required to unlock the full potential of cellulose as a sustainable building block.<br>

Intact Fibrillated 3D-Printed Cellulose Macrofibrils/CaCO3 for Controlled Drug Delivery

The tendency to use cellulose fibrils for direct ink writing (DIW) of three-dimensional (3D) printing has been growing extensively due to their advantageous mechanical properties. However, retaining cellulose in its fibrillated forms after the printing process has always been a challenge. In this study, cellulose macrofibrils (CMFs) from oil palm empty fruit bunch (OPEFB) fibers were partially dissolved for consistent viscosity needed for DIW 3D printing. The printed CMF structure obtained from optimized printing profiles (volumetric flow rate, Qv = 9.58 mm/s; print speed, v = 20 mm/s), exhibited excellent mechanical properties (tensile strength of 66 MPa, Young’s modulus of 2.16 GPa, and elongation of 8.76%). The remarkable structural and morphological effects of the intact cellulose fibrils show a homogeneous distribution with synthesized precipitated calcium carbonate (CaCO3) nanoparticles. The shear-aligned CMF/CaCO3 printed composite exhibited a sustained therapeutic drug release profile that can reduce rapid release that has adverse effects on healthy cells. In comparison with the initial burst release of 5-fluorouracil (5-FU) by CaCO3, the controlled release of 5-fluorouracil can be varied (48 to 75%) with the composition of CMF/CaCO3 allowing efficient release over time.