Fabrication of cationic cellulosic nanofibrils through aqueous quaternization pretreatment and their use in colloid aggregation.

The aqueous pre-treatment of cellulose with periodate and Girard' reagent T was employed as a novel and promising method to promote nanofibrillation of wood pulp and to obtain cellulosic nanofibrils with cationic functionality (CNFC). To demonstrate the feasibility of CNFCs in particle aggregation, a kaolin clay model suspension was aggregated by the CNFCs. Direct high-pressure homogenization of cationized cellulose resulted in nanofibrils exhibiting typical widths of 10-50 nm and cationic charge densities ranging from 1.10 to 2.13 mequiv.g(-1). The nanofibril suspensions existed in the form of highly transparent gels and possessed cellulose I crystalline structures. All of the CNFCs promoted strong aggregation of kaolin and produced voluminous kaolin-CNFC aggregates with lateral dimensions of several millimeters. Moreover, the CNFCs maintained good aggregation performance through wide pH (3-9) and temperature (25-60 °C) ranges. Thus, CNFCs were shown to be highly potential candidates for replacement of present synthetic soluble flocculation and coagulation aids.