Microcrystalline Cellulose from Bast Plants

Abstract

It was found that the chemical composition of flax fiber is common to cotton fiber, but differs from the stems of hemp and kenaf, softwood and hardwood because of higher content of ash, lesser lignin and pentosans content. Stems of hemp and kenaf compared with wood at approximately the same cellulose content have lesser lignin content, ash content and a much larger number of substances that dissolve in water and NaOH. It is shown that the water preliminary hydrolysis of bast plants compared with acid preliminary hydrolysis leads to less extraction of herbal minerals, hemicelluloses and cellulose fractions of low molecular weight. Increasing liquid to solid ratio in acid preliminary hydrolysis reduces mineral content in fibers and stems of plants, resulting in decreased yield and increased content of residual lignin in pulps. Cellulose was obtained by alkaline-sulfite alcohol method of bast plants delignification. Different schemes of bleaching organosolvent pulp using various charges of calcium hypochlorite, hydrogen peroxide and hydrochloric acid were investigated. It is shown that stage of hydrolysis organosolvent bleached cellulose by solutions of sulfuric acid and hydrogen peroxide provides microcrystalline cellulose with the required quality indexes.