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Advisor(s)
Abstract(s)
In order to ascertain the influence of the surfactants in the delignification of Pinus pinaster wood and the bleachability of the resulting pulps, 17 surfactants from four families of surfactants were tested, namely: cationic, anionic, non-ionic and amphoteric. The best results in terms of improved delignification, lower screen rejects and lighter unbleached pulps were obtained with the non-ionic surfactants. When compared with the reference, these cookings exhibit a decrease of the pulps kappa number by up to 6.2% and 39% in the case of the screen rejects, and an increase in the unbleached pulps reflectance factor of approximately 9%. The most promising samples in terms of reflectance factor were poly(ethyleneglycol) 1000-4%, block copolymer poly(ethyleneglycol)- poly(propyleneglycol) 1100-4% and poly(oxyethylene) 100 stearyl ether-1%. It was also established that the use of surfactants as cooking additives did not influence the bleachability, but allows savings of chlorine dioxide in the first bleaching stage (about 5.2%), with the consequent environmental and economical benefits.
Description
Keywords
Pinus pinaster Kraft pulp Surfactants Kappa number Reflectance factor Screen rejects Bleachability