(643c) Magnesium Hydroxide Nanoparticle Based Flocculation and Retention System

Nanoparticulate retention systems using nanosilicate and nanobentonite have been a research focus in papermaking wet end chemistry. Flake-shape magnesium hydroxide nanoparticle with particle size of 100-200nm in diameter and 1-10 nm in thickness was evaluated as a filler flocculation and retention aid. Nanoparticle properties including charge and dispersion ability was analyzed and modified to meet for the requirements of a nanoparticle retention aid. Flocculation and reflocculation of clay treated by the nanoparticulate retention system was investigated using the Focused Beam Reflectance Measurement (FBRM). The effect of the retention system on the filler retention and pulp furnish drainage rate were studied using Dynamic Drainage Analyzer (DDA). It was found that the combination of chemical modification using polyacrylate with ultrasonic treatment, the nanoparticle could be easily dispersed and stabilized over a month. It was also found that the new developed nanoparticulate retention system could not only improve filler retention but also facilitate water removal rate during the paper formation. The FBRM results indicated that the nanoparticle retention system could enhance filler flocculation and refocculation compared to the single polymer retention system using cationic polyacrylamide. The flocculation mechanism by this retention system was also proposed in this study.