Effect of alkaline extraction after acid hydrolysis in ECF bleaching

• Grant number: 15/25703-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2016
• End date: April 30, 2017
• Field of knowledge: Agronomical Sciences - Forestry Resources and Forestry Engineering - Technology and Use of Forest Products
• Principal Investigator: Gustavo Ventorim
• Grantee: Iliane Rodrigues de Oliveira
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Itapeva. Itapeva , SP, Brazil

Abstract

The acid hydrolysis stage (AHT), used in bleaching sequences of pulp, is primarily engaged in the degradation hexenuronic acid, which if is present on paper can affect brightness reversion, among other factors. Despite benefit using acid hydrolysis stage, when it comes to lignin degradation the pH of pulp is not the most appropriate, because lignin is more reactive in alkaline medium. Therefore, present work studies an optimization in bleaching process, obtaining the best possible use chlorine dioxide stage. By adding an alkaline extraction stage following AHT, increasing reactivity of lignin. Thus, in this study we use one kraft pulp delignified eucalyptus with oxygen from a pulp company. With this pulp will be performed different sequences bleaching ECF (Elemental Chlorine Free): OAHTD0(E+P)D1, OAHT/ED0(E+P)D1, OAHTED0(E+P)D1, OD0(E+P)D1, OAHT/D0(E+P)D1, OD0AHT(E+P)D1. The results to be discussed in this paper are: brightness, brightness reversion, chemical consumption in bleaching, pulp viscosity, and evaluation of the reactivity of lignin after acid hydrolysis. (AU)