New Insights into Lignin Modification During Chlorine Dioxide Bleaching Sequences (I): Chlorine Dioxide Delignification

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

“…[23] Brogdon et al have demonstrated that periodiate oxidized pulps, which contain significant levels of quinones (1.8 mmol/g lignin), have much lower kappa numbers (4 to 5 units) than unbleached pulp even though both pulps have almost similar amounts of Klason lignin. [23,24] These investigators established that KMnO 4 consumption during the kappa number test is directly related to the amount of carbon-carbon double bonds contained in the lignin and that quinones consume 1/3 less KMnO 4 than corresponding aromatic units.…”

“…[23,24] Experiments were performed on periodate oxidized cotton linters to confirm that cellulose oxidation did not influence KMnO 4 uptake during the kappa test; results indicated the oxidized linters (0.5 g) did not consume KMnO 4 . [24] …”

“…Demethoxylation is an indirect indicator of o-quinone formation. [24] The D 0 and periodate pulps in Table 1 were subjected to either caustic extraction (E) or oxygen-reinforced extraction (EO). The E stage caused the lignin/kappa number ratio of D 0 and periodate pulps to return to 0.15, comparable to that of the unbleached lignin.…”

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

“…[20 -22] The intent of our work is to provide a unified bleaching theory for chlorine dioxide bleaching sequences, correlating what we know from various published model studies to the changes that occur to the residual lignin structure as it progresses through a bleach sequence, and how each sequence interacts with one another. Our investigations have studied chlorine dioxide delignification (D 0 ) [23,24] and extraction (E and EO). [25,26] In this article, we propose how peroxide modifies residual D 0 lignin during (EP) and (EOP) stages and how it impacts the D 1 bleaching stage.…”

Detection of muconic acid type structures in oxidised lignins using 2D NMR spectroscopy 10th EWLP, Stockholm, Sweden, August 25–28, 2008

“…MATS are rather labile and present in oxidised lignin in small amounts either in open (I and I9) or in muconolactone (II-IV) forms (Figure 1). The presence of MATS in oxidised lignin is usually suggested based on analysis of its low molecular weight degradation products (Vilen et al 2000;Brogdon et al 2004), reactions with diazomethane (Sarkanen and Suzuri 1965), or based on FTIR and 13 C NMR spectra (Zarubin et al 1989;Hortling et al 1991;Evtuguin and Robert 1997;Runge and Ragauskas 1999). 13 C NMR spectroscopy is one of the most powerful tools for the detection/quantification of MATS, despite objective carbon assignment problems (Hortling et al 1991;Evtuguin and Robert 1997).…”