Study On Preparation Of Cationic Microfribrilliated Cellulose (CMFC) And Its Potential Use In Bile Acid Sorption

In this work,the great potential for using the cationic microfibrillated cellulose(CMFC)as a bile acid sorbent to decrease cholesterol was investigated.The curly wirelike CMFC with large specific surface area was obtained through a combination of enzymatic hydrolysis,quaternary amination and mechanical refining treatment.There were two types of CMFC obtained by the quaternization reaction;one was grafted with the N-(2-3-epoxypropyl)trimethylammonium chloride(EPTMAC);the other was cationic amphiphilic microfibrillated cellulose(CAMFC)grafted by quaternary ammonium groups that carried different hydrophobic substituents.Then,the sorption of a model compound for bile salts,sodium cholate,onto the CMFC in-vitro was determined.Various variables,contact time,initial concentration of sodium cholate,and the presence of salts,were investigated.The adsorption isotherm and kinetic studies were also described.Finally,the in-vitro bile acid sorption was initially performed by the investigation of various factors,such as charge density,length of the alkyl substituent,ionic strength,and hydrophobicity of the bile acid.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 cholestrayramine.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 study of the sorption process of sodium cholate in the presence of electrolytes showed that the selectivity for the sodium cholate was influenced by the nature of the competing anion and decreased in the order H2PO4-<HCO3-<Cl-,implying the interaction between sodium cholate and CMFC was electrostatic in nature.Both increasing charge and increasing hydrophobicity significantly contributed to the sorption of bile acid by CAMFC.The best sorption capacity was shown by the CAMFC which carried the functional group of an alkyl substituent with the length higher than C16;it was approximately 0.5-fold compared to cholestyramine.Ionic strength exhibited a small influence on bile acid sorption of the CAMFC with alkyl substituent.It was also found that the binding capacity of CAMFC with alkyl substituent as long as C16 was higher for more hydrophobic dihydroxylic bile acids in comparison with the trihydroxylic ones.