Phosphorylation of Cellulose in the Presence of Urea. Mechanism of Reaction and Reagent Impact.

A mechanism of cellulose phosphorylation in presence of urea is proposed. This model is correlated with the thermal stability of phosphorylating reactive mixture and the yield of phosphorylation for two different reagents: phosphoric acid and lauryl phosphate monoester. Three main successive reactions are involved in the formation of cellulose phosphate: (1) generation of ammonia by urea decomposition, (2) formation of phosphoramidate as intermediate reactive due to the reaction of ammonia with phosphate species, and (3) grafting the phosphate moiety to substrate due to the transfer of phosphate from phosphoramidate to cellulose. The proposed in vitro mechanism is supported by similar phosphorylation processes observed in some biochemical reactions. The limiting factor in the phosphorylation of cellulose is the formation of phosphoramidate intermediate.

Development of ash condensation performance of paper materials via saccharides and Nano HAP application

The ash condensation ability of the cigarette paper is an important factor affecting the cigarette grades. In this study, we put forward an effective method of improving this ability. Xanthan gum was successfully synthesized, applied as an ash integrator in the dip-coating process of cigarette paper production, and showed good performance. Cationic guar gum, cellulose phosphate and Hydroxyapatite (HAP) have been added in the pulp and showed better performance of the ash condensation property. The ash become much whiter and the scatter of the ash have been suppressed. Moreover, the further addition of HAP would result in a worse combustion efficiency, leading to the burning out of the cigarette in early time.

Aerogels from Cellulose Phosphates of Low Degree of Substitution: A TBAF·H2O/DMSO Based Approach

Biopolymer aerogels of appropriate open-porous morphology, nanotopology, surface chemistry, and mechanical properties can be promising cell scaffolding materials. Here, we report a facile approach towards the preparation of cellulose phosphate aerogels from two types of cellulosic source materials. Since high degrees of phosphorylation would afford water-soluble products inappropriate for cell scaffolding, products of low DSP (ca. 0.2) were prepared by a heterogeneous approach. Aiming at both i) full preservation of chemical integrity of cellulose during dissolution and ii) utilization of specific phase separation mechanisms upon coagulation of cellulose, TBAF·H2O/DMSO was employed as a non-derivatizing solvent. Sequential dissolution of cellulose phosphates, casting, coagulation, solvent exchange, and scCO2 drying afforded lightweight, nano-porous aerogels. Compared to their non-derivatized counterparts, cellulose phosphate aerogels are less sensitive towards shrinking during solvent exchange. This is presumably due to electrostatic repulsion and translates into faster scCO2 drying. The low DSP values have no negative impact on pore size distribution, specific surface (SBET ≤ 310 m2 g−1), porosity (Π 95.5–97 vol.%), or stiffness (Eρ ≤ 211 MPa cm3 g−1). Considering the sterilization capabilities of scCO2, existing templating opportunities to afford dual-porous scaffolds and the good hemocompatibility of phosphorylated cellulose, TBAF·H2O/DMSO can be regarded a promising solvent system for the manufacture of cell scaffolding materials.

Cellulose Phosphate Applied in the Removal of the Drug Acetaminophen from Aqueous Media

The cellulose phosphate used for this work was obtained by a reaction between cellulose and sodium trimetaphosphate (STMP) at pH 10. The material obtained was characterized by 31P nuclear magnetic resonance (31P NMR) spectrometry and energy-dispersive X-ray spectroscopy (EDS). In the 31P NMR results, the two peaks at 2.05 and 7.96 ppm are related to phosphorous. The EDS indicated the presence of 5.47% of incorporated phosphorus which proved the modification. The material obtained was applied in the removal of the pharmaceutical drug acetaminophen (acetaminophen) from aqueous media. The maximum adsorptions of the drug in the cellulose phosphate was 60.7, 56.7, and 60.0 mg g-1 at the temperatures 298 K, 308 K, and 318 K, respectively, in 120 minutes at pH7. The plot traced from the data best aligns with the pseudo-second order kinetic model and with the physical-chemical model proposed by Freundlich.