Study of xylan and cellulose interactions monitored with solid-state NMR and QCM-D

Abstract

Development of physical properties of bleached eucalyptus kraft pulp is typically based on the refining process. However, many studies have reported that xylan deposition is a viable alternative. As the mechanisms of xylan and cellulose interactions are not clear, the main goal of this study was to achieve a better understanding of these interactions. Considering that a sample of pulp enriched with xylan is a very complex matrix, a model system was developed. Cellulosic thin films were prepared by spincoating and the Langmuir-Schaefer (LS) method from trimethylsilylcellulose (TMSC). Their interactions with xylan were analyzed using the quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The topological changes on cellulose were studied using atomic force microscopy (AFM). For the 13C solid-state nuclear magnetic resonance (NMR) studies, samples were prepared using commercial microcrystalline cellulose (MCC) and xylan. The xylan was extracted from bleached birch kraft pulp using a cold caustic extraction (CCE) method. The QCM-D monitoring showed deposition only with higher concentrations of xylan solution (1 mg · l−1) for the LS method. The AFM images showed that xylan deposits as agglomerates on the cellulose surface, and the NMR experiments showed that there are interactions for the more ordered region of the cellulose fiber and for the less-ordered region.

Kinetics and Thermodynamics of Hemicellulose Adsorption onto Nanofibril Cellulose Surfaces by QCM-D

“…21 According to the molecular entanglement theory, the higher the molecular weight, the more entangled the molecular chains are and more adsorbed water between the molecules, resulting in a higher adsorption capacity and a higher dissipation value. 22,23 BH ht was tightly bound on the surface of cellulose, less adsorbed water moved with the shear layer, and the dissipation was lower. Thereby, compared with the absorption of BH ae , the formed adsorption layer of BH ht had stronger rigidity and binding force (Figure 3).…”

“…This was because the hemicellulose BH ae with a large molecular weight was loosely bound to the cellulose surface, and the movable polymer segments moved together with the adsorbed water during the shaking and shearing processes, resulting in an increase in adsorption capacity . According to the molecular entanglement theory, the higher the molecular weight, the more entangled the molecular chains are and more adsorbed water between the molecules, resulting in a higher adsorption capacity and a higher dissipation value. , BH ht was tightly bound on the surface of cellulose, less adsorbed water moved with the shear layer, and the dissipation was lower. Thereby, compared with the absorption of BH ae , the formed adsorption layer of BH ht had stronger rigidity and binding force (Figure ).…”

Solid State NMR Spectroscopy a Valuable Technique for Structural Insights of Advanced Thin Film Materials: A Review

“…Ultra-high magnetic fields resolve to a certain extent the line-broadening associated with the second-order quadrupole coupling [106]. Applying multi-field experiments is a decisive exploration strategy for extracting structural information and exploring the chemical environment of exotic quadrupole nuclei such as 2 H, 17 O, 33 S and 35 Cl in organic thin films and 7 Li, 11 B, 51 V, 59 Co, 67 Zn, 71 Ga and 89 Yb in inorganic ones.…”

The Coordination Structure of the Extracted Nickel(II) Complex with a Synergistic Mixture Containing Lix63 and Versatic10

“…The recovery of nickel and cobalt from laterite ores has become more important in recent years due to the increase in nickel consumption. 4 In addition, laterite ores host various impurities (such as iron, calcium, magnesium, manganese, aluminum, zinc, chromium, and other 3d transition metals), whose contents vary depending on the location of the ore. 5 High-pressure acid leaching is a widely used method to process laterite ores, which results in the production of acidic leach liquors containing Ni 2+ , Co 2+ , Ca 2+ , Mg 2+ , Mn 2+ , and so on.…”