In this work, a series of cationic microfibrillated cellulose (CMFC) were prepared by introducing quaternary amine groups, and the sorption of a model compound for bile salts, sodium cholate, in vitro was determined. Various variables, contact time, initial concentration of sodium cholate, and the presence of salts, were investigated. Experimental results showed that the in vitro binding of sodium cholate of the CMFC was 57.95 mg/g, which was about 70% lower than that of cholestyramine. The isotherm data were analyzed according to Langmuir, Freundlich, and Tempkin models. Characteristic parameters of each model were determined. Results also showed that the Langmuir isotherm performed the best correlation for the sorption of sodium cholate onto the CMFC, and the maximum capacity, Qmax was 416.67 mg of sodium cholate per gram of CMFC. The sorption kinetics underwent a pseudo-second-order equation, suggesting a chemisorptions mechanism. Additionally, the presence of salts in the reaction system greatly prevented the CMFC sorption toward cholate, implying the interaction between sodium cholate and CMFC was electrostatic in nature. All these results support the great potential for using the CMFC as a sorbent to decrease cholesterol.

This study aimed to improve the stability of nanofibrillated cellulose (NFC) in an electrolyte containing system, which was achieved by the grafting of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) via the ceric ammonium nitrate-induced polymerization process. The results indicated that upon grafting the salt resistance and thermal stability of NFC were significantly improved. Moreover, the stability of the modified NFC increased with the AMPS loading. Compared to the control (the original NFC), the poly-AMPS/NFC (357.5 mg/g AMPS) exhibited much improved stability in a 400 mmol/L NaCl solution, and its viscosity was 350 mPa s. The thermogravimetric analysis results showed that the initial decomposition temperature of the modified NFC increased from 265 to 330 °C. Transmission electron microscopy (TEM) observations showed that the main morphologic features of NFC were not altered, suggesting that the grafting reaction occurred on the fiber surface. The modified NFC can have promising industrial applications, such as oil recovery.

•Addition of TOCNs improved the mechanical properties of the WPU coating.•Both hydrogen bonds and continuous TOCNs network in the coating contributed to the observed improvements.•The results can be predicted by the Ouali model at the TOCNs content exceeding the percolation threshold.•The pencil hardness of the coating was enhanced with the addition of TOCNs.In this work, TEMPO-oxidized cellulose nanofibers (TOCNs) were investigated as a green additive to the waterborne polyurethane (WPU) based coating, for improving its mechanical properties. The structure, morphology, mechanical properties and performances of the WPU/TOCNs coating were determined. Results showed that TOCNs had good compatibility to the WPU coating, and significantly enhanced the mechanical properties of the coating. The Halpin-Tsai and Ouali models were used to fit for the Young’s modulus of the resulting coating, and good agreements were found between the Ouali model and experimental results when the TOCNs content exceeded the critical percolation threshold (0.7 vol% or 1.0 wt%). It was also found that the pencil hardness of the coating was improved with the addition of TOCNs. However, AFM and pull-off test revealed the negative effects of the TOCNs addition on the surface roughness and adhesion strength of the coating to the wood surface.

In this paper, a cellulase pretreatment was studied prior to the acid hydrolysis to decrease the total acid usage during the cellulose nano-crystals (CNC) preparation from a bleached softwood kraft pulp. Cellulase pretreatment facilitates the subsequent acid hydrolysis to produce CNC with similar quality to that of the control, but at a lower sulfuric acid concentration. The underline mechanism is that cellulase pretreatment led to the formation of more carbonyl groups which can be oxidized into carboxyl groups in the subsequent acid hydrolysis, furthermore, more hydroxyl groups are exposed, thus esterification into sulfonic groups can be enhanced. The results showed that with a cellulase dosage of 4.8 u/g (based on dry pulp) in the pretreatment stage, the sulfuric acid concentration can be decreased from 64 to 40 wt% without compromising the quality of resulting CNC particles. Other results from charge properties, Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) analyses also supported the conclusions.

•Improving the re-dispersity of CNC was by physical adsorbing PEG.•PEG1000 dosage of 5% was sufficient to enhance the re-dispersity of CNC.•The mechanism of the improvement of CNC re-dispersity was investigated.•CNC crystallinity and thermal stability were not affected by the adsorption of PEG.In this work, the adsorption of polyethylene glycol (PEG) onto cellulose nano-crystals (CNC) was investigated for preparing re-dispersible dried CNC. Results showed that the re-dispersity of CNC in water can be significantly enhanced using a PEG1000 dosage of 5 wt% (based on the dry weight of CNC). The elemental analysis confirmed the adsorption of PEG onto the CNC surface. Transmission electron microscopy (TEM) was used to characterize the dry powder and indicated that the irreversible agglomeration of CNC after drying was essentially eliminated based on the PEG adsorption concept. Thermo-gravimetric analysis (TGA) and X-ray diffraction (XRD) suggested that CNC crystallinity and thermal stability were not affected by the adsorption of PEG. Thus, the adsorption of PEG has great potential for producing re-dispersible powder CNC.

•Cationic amphiphilic MFC with different chemical structures is synthesized.•Increasing charge density increases the sorption capacity of CMFC.•Increasing alkyl length increases the sorption capacity of the modified CMFC.•Sorption behavior of the modified CMFC is less influenced by the ionic strength.•Sorption capacity of the modified MFC is higher for deoxycholate than cholate.In this work, Micro-fibrillated Cellulose (MFC) was cationically modified by quaternary ammonium groups with different chemical structures aiming to improve the sorption capacity to bile acid. The in-vitro bile acid sorption was performed by investigating various factors, such as quaternary ammonium group content and length of its alkyl substituent of the modified cationic MFC (CMFC), ionic strength, initial concentration and hydrophobicity of bile acid. The results showed that the sorption behavior of the modified CMFC was strongly influenced by the quaternary ammonium group content and the lengths of its alkyl substituent, the sorption capacity for the modified CMFC with a C18 alkyl substituent, was approximately 50% of that of Cholestyramine. The experimental isotherm results were well fitted into the Temkin model. The effect of salts in the solution was smaller for the bile acid sorption onto the hydrophobic CMFC than the CMFC. It was also found that the binding capacity of CMFC was higher for more hydrophobic deoxycholate in comparison with cholate.