New Insights into Lignin Modification during Chlorine Dioxide Bleaching Sequences (IV): The Impact of Modifications in the (EP) and (EOP) Stages on the D₁ Stage

Abstract

Peroxide-reinforced extractions ((EP) or (EOP)) of D 0 pulps lower both post-extraction kappa numbers and Klason lignins more than either E or (EO). An oxygen-reinforced extraction (EO) results in lower kappa numbers, but affords comparable Klason lignins as an E stage (1.2% lignin). Quinonoid structures in (EO) stocks are similar to those of the D 0 pulps (1.7 mmol/g lignin). Peroxide inclusion in EP and EOP appeared to eliminate both quinonoid and muconic acid moieties. These observations were confirmed with (EP) treatment of reference pulps (periodate or periodate-peracetic acid) that contain significant levels of either quinones or muconic entities. The D 1 bleachability order, from easiest to hardest, was D 0 (EOP) . D 0 (EP) % D 0 (EO) . D 0 E. An identical order was found for how quickly the yellow chromophores (b à value) are eliminated. All extracted pulps, regardless of the type of extraction employed, approach a common D 1 asymptotic brightness (86 ISO) and b à value (4.2) when excess ClO 2 is applied. The main difference among these pulps was how quickly the asymptotic limits are approached as a function of ClO 2

Clean Bleaching Engineering Practice for Bagasse Pulp: Totally Chlorine-Free and Elemental Chlorine-Free Bleaching Realized with the Same Production Line

“…In an (EO) or (EOP) stage, this can be partially or totally pressurized during the extraction reaction. Various studies have noticed that the bleachability of pulp various in an order of (EOP) > (EP) > (EO) >E1 (Brogdon and Lucia (2005); Zhao et al 2010).…”

New Insights into Lignin Modification during Chlorine Dioxide Bleaching Sequences (III): The Impact of Modifications in the (EO) versus E Stage on the D1Stage

“…Through the results of this work, we hope to establish some of the fundamental chemistry that occurs during the (EO) and D 1 stages. In a companion article, [26] we examine how peroxide affects oxidative reinforced alkaline extraction stages (e.g., (EP) and (EOP)).…”

Simultaneous determination of chlorine dioxide and hypochlorous acid in bleaching system

“…In the paper industry, the so-called elemental chlorine-free (ECF) bleaching technology, i.e., using chlorine dioxide (ClO 2 ) as the main bleaching chemical has become dominant all over the world in the production of bleached chemical pulps (Barroca et al 2001;Hamzeh et al 2007). This shift can be attributed to the high-quality pulp product, low-environmental impact, and reasonable production cost of the process (Brogdon et al 2005). The residual chlorine dioxide in a pulp bleaching system is one of the most important parameters from the viewpoints of both quality control and process operation (Sullivan et al 1998).…”