Review of Cellulose Non-Derivatizing Solvent Interactions with Emphasis on Activity in Inorganic Molten Salt Hydrates

Abstract

During cellulose dissolution in non-derivatizing solvents, the inter-and intramolecular hydrogen bonds of the polymer are deconstructed. This occurs either by hydrogen bond formation between one or more components of the solvent systems and the hydroxyl groups of the cellulose or by coordination bond formation between the metal ion present in the medium and the hydroxyl group of cellulose molecules. None of the polymer molecules are actually chemically modified during dissolution. In the first part of this review, we examine the literature pertaining to the different interaction mechanisms between cellulose and non-derivatizing solvent systems with emphasis on the inorganic molten salt hydrates. In the second part of this effort, we further review inorganic molten salt hydrates from the point of view of the changes they impart to the physical properties of the cellulose and the various chemical reactions that can be performed in it.

Effective conversion of biomass into bromomethylfurfural, furfural, and depolymerized lignin in lithium bromide molten salt hydrate of a biphasic system

“…In a perfect molten salt hydrate, all water molecules are tightly bound to the inner coordination sphere of the cation, leaving the anion naked in the system. 40 and able to interact with the O of cellulose hydroxyl groups when dissociated from the coordinated water molecules by heating and, in particular, when part of the water in the system is consumed for hydrolysis of cellulose and hemicelluloses. The cellulose-Br À and cellulose-Li + associations or interactions disrupt the inter-and intra-molecular hydrogen bonding of cellulose, thereby breaking the tight crystalline matrix of cellulose, thus leading to the swelling and dissolution of cellulose.…”

Cellulose–solvent interactions from self-diffusion NMR

“…In fact, except for direct application in its natural fiber form, cellulose cannot melt, it should be processed via dissolution or derivatization. Several solvents were studied to dissolve cellulose showing several cellulose-solvent interaction mechanisms (Sen et al 2013). Nuclear magnetic resonance (NMR) is one of the most suitable techniques to study cellulose dissolution and aggregation (Isogai 1997;Kamide et al 1985;VanderHart and Atalla 1984).…”

Removal of anionic dyes in aqueous solution by flocculation with cellulose ampholytes

“…In addition, cationized cellulose, produced by homogeneous cationization with 2,3-epoxypropyltrimethylammonium chloride (EPTMAC), was reported to exhibit good cationic flocculation ability toward kaolin suspensions [25]. However, as cellulose is highly crystallized by a strong network of inter-and intra-molecular hydrogen bonds, its dissolution requires a time-consuming processing with unpopular solvents such as aqueous sodium hydroxide/urea solution, lithium chloride/dimethyl sulfoxide, tetra-n-butylammonium fluoride/dimethyl sulfoxide, and specific ionic liquids, and/or preswelling by sequential solvent change and heating [26]. In our previous work, cellulose ampholytes (CAms) containing both cationic quaternary ammonium sodium salt and anionic carboxymethyl groups were prepared from homogeneous etherification of CMC dissolved in aqueous solution in the presence of EPTMAC as cationic reagent.…”