Effect of natural aging on the oxidative and reductive bleaching of the deinked Pulp

Document Type : Research Paper

Authors

1 Ph.D. Student, Paper Science and Engineering Department, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I.R. Iran

2 Assoc. Prof., Paper Science and Engineering Department, Faculty of Wood and Paper Engineering, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, I.R. Iran

Abstract

Regarding the increase of the bleaching chemicals usage which caused by aging of the recycled papers and intensifying the negative environmental effects, it is detrimental to investigate the proper methods for decreasing these negative effects. Thus, the present study was aimed to investigate the effect of natural aging on the optical (brightness, yellowness, opacity) and strength properties (tensile, burst and tear indices) of the mixed old newspaper (ONP)/and old magazine (OMG) deinked pulps and also bleached with oxidative and reductive bleaching agents. Local offset-printed ONP and OMG were naturally aged for five months, then deinked by flotation and bleached with hydrogen peroxide (H2O2) and formamidine sulfinic acid (FAS) in both single-stage and two-stages bleaching operations. Result showed that the natural aging decreased the brightness and all strength indices, but the opacity and yellowness increased compared to those of the newly recycled papers without aging. In addition, reductive bleaching (using FAS) was found more effective than oxidative bleaching (using H2O2) in improving all optical and strength properties of the hand-sheets. In addition, in two stages bleaching sequences, it was observed to be most appropriate to use FAS as the latter bleaching chemical after H2O2. Therefore, it can be totally concluded that the application of the reductive bleaching system (by FAS) is apparently more effective and efficient than oxidative bleaching system (by H2O2) in both single-stage and two-stages bleaching operations of the deinked pulps from offset-printed of wood-containing recycled papers in terms of the optical and mechanical properties.

Keywords

Forest and Wood Products
Volume 72, Issue 2
August 2019
Pages 171-181

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