Researches on the Bleaching of NSSC Pulps With OP Sequences

Authors: Mustafa USTA

Abstract: In this study, to determine optimum bleaching conditions of NSSC pulps with OP sequences 15 oxygen prebleaching trials and 8 hydrogen peroxide bleaching trials were realized. As a result of statistical analysis of the data obtained, optimum oxygen and peroxide bleaching conditions of NSSC pulps were found as indicated below: Oxygen prebleaching; Reaction temperature : 110¼C Reaction time : 20 min. NaOH charge : 5% Consistency : 12 % Magnesium sulfate : 0.5 % Oxygen pressure : 12 % Hydrogen prebleaching; Reaction temperature : 80¼C Reaction time : 90 min. NaOH charge : 4% Consistency : 1.5 % Magnesium sulfate: 10 % Oxygen pressure : 1 % Brightness, breaking length, burst and tear index of NSSC pulps bleached with OP sequences were found 83.60%, 4.63%, 48,87% and 20.70% respectively higher than those of unbleached NSSC pulps. It is also possible bleaching NSSC pulps with OP sequences as high as 72 brighthess level. The content of colored and toxic organic material of OP bleaching sequences effluents is lower than those of chlorine based bleachings. The pulps bleached with OP sequences can be used in the production of printing and tissue papers in combination with sulphate and sulphite pulps. Additionally, these pulps may also be used in the production of newspaper.

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