Estudo das reações da lignina e dos ácidos hexenurônicos em polpa kraft de eucalipto com oxigênio, dióxido de cloro, ácido sulfúrico e ozônio

• Autor(a) principal: Ventorim, Gustavo
• Data de Publicação: 2004
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/553
• topic: Cinética; Dióxido de cloro; Ozônio; Ácido hexenurônico; Polpa kraft; Eucalipto; Kinetics; Chlorine dioxide; Ozone; Hexenuronic acid; Kraft pulp; Eucalyptus; Lignin; CNPQ::CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL::TECNOLOGIA E UTILIZACAO DE PRODUTOS FLORESTAIS::TECNOLOGIA DE CELULOSE E PAPEL

The kinetics of lignin and hexenuronic acid reactions with chlorine dioxide, sulfuric acid and ozone and its implications on oxygen delignification (Pre-O2) and bleaching Z-ECF of eucalyptus kraft pulp was investigated. Chapter I presents the kinetical studies; chapter II discusses the influence of lignin and HexA s ou oxygen delignification performanece; chapter III addresses the impact of lignin and HexA s on ozonolyses performance, with special focus on reaction pH. From chapter I it is concluded that maximum reaction rate (Vmax) of chlorine dioxide with lignin and HexA s is 57.2 and 26 mmol/kg/min, respectively, for Brown pulp and 26.7 and 13 mmol/kg/min, for oxygen delignified pulp. In the case of sulfuric acid hydrolysis, Vmax were 1.11 and 0.93 mmol/kg/min, respectively, for brown pulp and 1.95 and 0.80 mmol/kg/min, to oxygen delignification pulp. The kinetical results suggest that pulp reaction with chlorine dioxide should supercede acid hydrolyses and precede ozonolyses with the AHT/D and D/Z been indicated. Oxygen delignified pulp lignin and HexA s react two fold more slowly with chlorine dioxide that brown pulp lignin and HexA s, but there two types of pulps react at similar speed with ozone. In chapter II it was conclude that the values of industrial pulps (KobudoMARI & ITC) kappa (11.4-21.7) and HexA s content (23.2-56.7 mmol/kg) have no significant impact on oxygen delignification performance, as measured by process efficiency, selectivity, brightness gain and yield and filtrate organic load (TOC, COD). Chapter III reveals that pulp ozonolysis efficiency and selectivity are substantially decreased when pulp HexA s are previously removed by are acid hydrolysis treatment. Bleaching sequence contains ozonolysis and acid hydrolysis treatments are very inefficient. The reaction of ozone with HexA s require less acidty then with lignin. Increasing ozonolysis pH from 2.5 to 7.0 is justified for sequence of the Z/D(EOP)D type but not viable to sequence of the Z/ED(PO) type.