Effect of Mild Acid Hydrolysis Parameters on Properties of Microcrystalline Cellulose

The effects of mild kraft pulp hydrolysis conditions (reaction time, temperature, pulp consistency, and acid dosage) with sulfuric acid (H2SO4) on the properties of microcrystalline cellulose (MCC) were investigated. The degree of polymerization (DP) of cellulose rapidly decreased at the initiation of hydrolysis and leveled off after a certain reaction time, depending on the hydrolysis conditions. The intensity of the hydrolysis treatment greatly affected the cellulose particle size. Compared to the intensive treatment, the mild conditions resulted in a broader particle size distribution, while smaller particles with a narrow size distribution were obtained under severe conditions. However, the particle size leveled off at a hydrolysis factor (P-factor) of 300. The results suggest that after a certain P-factor (300), severe hydrolysis conditions have no advantage over mild ones as related to the MCC particle properties. Because of favourable reaction conditions (short delay time, moderate temperature, and small amounts of chemicals), this method can be implemented on an industrial scale in a chemical pulp mill.