Comparative Study on the Characteristics of Environmental Friendly Bleaching of Organosolv NonWood Pulps by Hydrogen Peroxide

摘要

In this research, the chemistry of peroxide bleaching effect on rice straw pulp has been thoroughlystudied both with lignin model compounds and with degradation of carbohydrates. Rice straw wascooked in by soda-(ethanol, diethylene glycol, dimethyl formamide) and kraft type. After three stageperoxide bleaching of organosolv pulps, some similarity in behavior of brightness and peroxideconsumption for each alkali percentage has been observed. Final brightness of 63-70% ISO wasattained for all tested pulps. The carbohydrates reaction in peroxide delignification results in a loss ofviscosity due to attack by hydroxyl radicals to the carbohydrates chains. The yield loss in chemicalpulping due to degradation and dissolution of polysaccharides (particularly hemicellulose) is substantialand constitutes a serious drawback of the process. The high obtained bleached yield for organosolvpulps (in the range of 90-91% o.d.p.) point to limited organosolv carbohydrate degradation duringperoxide bleaching.