Use of perborate in the bleaching of ethanolamine pulp from olive wood

Abstract

In this work, we studied the influence of the bleacher concentration (2.5-5.5%), temperature (60-80 ºC) and time (60-180 min) on the reagent (perborate) consumption by dry pulp, various properties of the bleached pulp (yield, kappa number, brightness and viscosity/kappa number ratio), and some physical properties of paper sheets obtained from it (tear index, burst index, stretch and breaking length). The pulp was previously obtained by ethanolamine-soda-anthraquinone cooking of olive wood. A face-centred composite factor design was used to derive equations relating the pulp properties to the operational variables with a view to identifying the optimum operating conditions. The equations thus obtained reproduced the experimental results with errors less than 10% in all cases. The most suitable operating conditions were found to be a low temperature (60 ºC), a long time (180 min) and a high perborate concentration (5,5%). Because the pulp brightness achieved never exceeded 63% -not even under the most drastic conditions-, the process should not be used with one-step bleaching sequences.