Dissolution and Hydrolysis of Bleached Kraft Pulp Using Ionic Liquids

Abstract

Forestry industries in Chile are facing an important challenge—diversifying their products using green technologies. In this study, the potential use of Ionic Liquids (ILs) to dissolve and hydrolyze eucalyptus wood (mix of Eucalyptus nitens and Eucalyptus globulus) kraft pulp was studied. The Bleached Hardwood Kraft Pulp (BHKP) from a Chilean pulp mill was used together with five different ILs: 1-butyl-3-methylimidazolium chloride [bmim][Cl], 1-butyl-3-methylimidazolium acetate [bmim][Ac], 1-butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO4], 1-ethyl-3-methylimidazolium chloride [emim][Cl], 1-ethyl-3-methylimidazolium acetate [emim][Ac]. Experimentally, one vacuum reactor was designed to study the dissolution/hydrolysis process for each ILs; particularly, the cellulose dissolution process using [bmim][Cl] was studied proposing one molecular dynamic model. Experimental characterization using Atomic Force Microscopy, conductometric titration, among other techniques suggest that all ILs are capable of cellulose dissolution at different levels; in some cases, the dissolution evolved to partial hydrolysis appearing cellulose nanocrystals (CNC) in the form of spherical aggregates with a diameter of 40–120 nm. Molecular dynamics simulations showed that the [bmim][Cl] anions tend to interact actively with cellulose sites and water molecules in the dissolution process. The results showed the potential of some ILs to dissolve/hydrolyze the cellulose from Chilean Eucalyptus, maintaining reactive forms.

Relationship between Structural Characteristics of Cellulose Nanocrystals Obtained from Kraft Pulp

“…The colloidal stability of CNC samples was assessed through the measurement of Zeta potential ( ϕz ). The Zeta potential was determined in samples with a solids concentration of 0.05% w/w (pH = 6.0, 25 °C) using a Zeta potential equipment (Malvern Panalytical, Zetasizer Nano S, UK), the zeta potential values were obtained in three runs with 32 measurements each, the final values were calculated as the average [ 30 ].…”

A Review of Lignocellulosic-Derived Nanoparticles for Drug Delivery Applications: Lignin Nanoparticles, Xylan Nanoparticles, and Cellulose Nanocrystals

“…The pretreatment process selection depends on cellulose content in raw material, removed components, and raw material characteristics. In the early development phase of CNCs research, several methods were explored to isolate CNCs from natural resources containing high cellulose content, such as acid hydrolysis, enzymatic hydrolysis, oxidation, steam explosion, subcritical water, ionic liquids, and high-pressure homogenization methods [59][60][61][62][63]. Presently, the acid hydrolysis method is the most widely used method for isolating CNCs due to its simplicity, ease of doing, and desired product characteristics [56].…”

A Review of Cellulose Coarse-Grained Models and Their Applications

“…Figure 1 presents the most commonly used mapping schemes (found in more than one publication) for polysaccharides. In many studies, each AGU has been represented by three CG beads [27][28][29]31,35,36,38,39,42,43,57]. Two widely used mapping schemes with three CG beads are illustrated in Figure 1a,b.…”

“…This model used Boltzmann inversion to parameterize the bonded interactions and a Monte Carlo simulated annealing to obtain the non-bonded parameters, which were modeled by the Morse potential. The same mapping as in the M3B model was subsequently adopted in several other studies [35,36,38,39,57]. Although in these studies, the mapping scheme is similar, the potential functions used to represent the interactions (bonded and non-bonded) are different.…”