Yield loss during bleaching of pulp of Pinus radiata previously delignified with oxygen
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SHORT RESEARCH AND DISCUSSION ARTICLE
Yield loss during bleaching of pulp of Pinus radiata previously delignified with oxygen Regina Maria Gomes 1 Elias Costa de Souza 1
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& Renato de Oliveira Baptista & Eduardo Leite de Almeida
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& Ana Claudia Gama Batista
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&
Received: 22 March 2020 / Accepted: 27 September 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The pulp bleaching process removes or transforms the chromophore groups in the pulp, so that the final product reaches a desired brightness. However, this chemical treatment inevitably results in yield loss. Therefore, the objective of this work was to quantify the yield loss caused during the bleaching of kraft pulp of Pinus radiata delignified with oxygen. The material was submitted to three distinct ECF sequences (D0(EPO)D1D2, D0(EPO)D1P, and Z/EDP). At the end of each bleaching stage, the pulp brightness and the loss of gravimetric yield of the process were determined, and the generated filtrates were collected. From these filtrates, the pollutant load of the effluent was determined by measuring the content of total dissolved solids, the chemical oxygen demand, the concentration of total organic carbon carbon, and the adsorbable organic halogens. Among the whole sequences, the Z/EDP sequence had the lowest gravimetric yield, the highest pollutant load in the collected filtrate, and lowest potential for adsorbable organic halogens generation. There was good correlation between the loss of yield from the bleaching process and the organic load of the generated effluent; and among the techniques studied, the quantification of total organic carbon was the most appropriate method for the indirect quantification of the yield loss during the bleaching process of the studied material. Keywords ECF sequence . COD . TOC . Bleaching stages . Indirect determination
Introduction Brazil was the second largest wood pulp producer in the world in 2018, with output of 21.1 million metric tons of cellulosic pulp, approximately 11% of which was long-fiber kraft pulp (Indústria Brasileira de Árvores – IBÁ 2019). The cellulosic Responsible editor: Philippe Garrigues * Elias Costa de Souza [email protected] Regina Maria Gomes [email protected] Renato de Oliveira Baptista [email protected] Eduardo Leite de Almeida [email protected] Ana Claudia Gama Batista [email protected] 1
Forest Sciences Department, “Luiz de Queiroz” College of Agriculture, University of São Paulo (ESALQ/USP), Avenida Pádua Dias, 11 Cx. P. 9 13, Piracicaba, SP 418-900, Brazil
pulp obtained from cooking pine wood is used for the production of paper with greater resistance and can be used with a low level of brightness, such as for the production of unbleached kraft paper and cardboard, or even for production of bleached paper, such as filter paper and some types of special absorbent paper (KLABIN. Negócios e Produtos: Celulose 2020). The bleaching of chemical cellulosic pulps is carried out in order to increase its brightness, with the least impact o
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