Análise de reversão de alvura em diferentes sequências de branqueamento ECF

• Autor(a) principal: Camargo, Sâmique Kyene de Carvalho Araújo [UNESP]
• Data de Publicação: 2014
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/142887; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2016-07-01/000843109.pdf
• topic: Celulose; Branqueamento; Eucalipto; Madeira - Quimica; Cellulose

This work aims to analyze the brightness reversion of different ECF bleaching sequences. The brightness reversion is caused for the presence of residual lignin, hexenuronic acids, metals, carboxyl and carbonyl groups in the pulp to be bleached, and also by pH, temperature, heat, and humidity thereof. In the production of printing and writing paper, the raw material used is the pulp bleached with 90% ISO brightness. The pulp brightness should remain stable even after shipping and storage. This it is necessary combination of bleaching reagents that remove or modify the substances that cause the brightness reversion. The experiments were conducted in the Laboratory of Cellulose Technology, UNESP/Campus Itapeva. Bleaching, D0(E+P)D1D2, D0(E+P)D1P, AHTD0(E+P)D1D2, AHTD0(E+P)D1P, samples oxygen delignified pulp in polyethylene bags were made, aiming to reach 90% ISO brightness. To control the temperature bleaching bath thermostated was used. The analyzes compared the merit this work were: viscosity, kappa, brightness AD, OD brightness and brightness reversion. The results show advantage using acidic hydrolysis stage for reduction of brightness reversion due to removal hexenuronic acids and metals, despite the substantial reduction in viscosity pulp. The brightness reached end of bleaching with introduction this stage was higher. Moreover, the inclusion stage generates a total savings in amount used in bleaching reagent. The chlorine dioxide stage proves to be quite selective, because without acid hydrolysis in sequence with final chlorine dioxide viscosity loss was minor. The final peroxidation was of great importance gain and stability brightness, this occurs because stage removal carbonyl groups. The results also show that same amount reagent as chlorine sequence with final peroxidation reached a higher level brightness to the final chlorine dioxide stage. However best results brightness and brightness reversion...