UM NOVO CONCEITO DE BRANQUEAMENTO DE POLPA KRAFT DE EUCALIPTO COM OZÔNIO EM MÉDIA CONSISTÊNCIA

• Autor(a) principal: Gomes,Valéria J.
• Data de Publicação: 2017
• Outros Autores: Colodette,Jorge L.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Química Nova (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422017000100054
• topic: eucalypt; bleaching; hot acid hydrolysis; ozone; hexenuronic acid

The effect of hot acid hydrolysis (A-stage) pretreatment on the ozone (Z/E) performance at medium consistency was evaluated. An experimental plan was set up involving full optimization of A and Z/E stages for an oxygen delignified eucalypt kraft pulp. A-stage caused significant kappa and HexA drop, and the optimum condition for this stage being pH 3.0, 90 ºC, 120 minutes at 10% consistency. For A-stage pretreated pulp, the conditions for maximum Z/E-stage efficiency and selectivity were pH 2.5, 40 ºC, 5.0 kg O3 adt-1 pulp for the (Z/)-treatment and pH 10.5 for the alkaline extraction (E). The values of kappa drop per kilogram of ozone applied were 1.04 and 1.18 for A-stage pretreated and reference pulps, respectively. Since the A-stage pretreatment did not decrease the (Z/E)-stage efficiency to a large extent, such stages are complementary rather than competitive. The potential of the A-stage pretreatment to save bleaching chemicals is quite large given that pulp kappa number (brightness) after Z/E and AZ/E treatments were 5.5 (brightness 67.3% ISO) and 1.1 (brightness 72.6% ISO), respectively. The impact of the A-stage pretreatment on overall bleaching performance, comparing the sequences Z/EDP and AZ/EDP will be a matter of other publication on the subject.