Carboxymethylated cellulose nanocrystals as clay suspension dispersants: effect of size and surface functional groups

In this study, cellulose nanocrystals (CNC) were produced with different sizes; they were then carboxymethylated to generate carboxymethylated CNC (CCNC) to be used as dispersants for a kaolinite suspension at different pH. It was observed that larger CNC rendered CCNC with a higher surface charge. The largest CCNC (CCNC3) adsorbed more on kaolinite particles and impacted the surface charge density of the particles more dramatically than did other CCNCs. Furthermore, CCNC3 stabilized the kaolinite suspension at a lower dosage and to a higher degree than other CCNCs, and the strength of stability was greater for CCNC3 compared to the other ones. Also, CCNC was a much better dispersant than CNC as it impacted the level and strength of kaolinite system’s stability more pronouncedly. Furthermore, a larger CCNC, which can be produced under milder hydrolysis reactions of pulp, can respond to carboxymethylation more effectively and make a more efficient dispersant for the kaolinite suspension, which is advantageous for industrial applications.