Quantification of Muconic Acid-Type Structures in High Molecular Weight Material from Bleach Plant Effluents

Abstract

Chemical oxygen demand (COD) and total organic carbon (TOC)COD and TOC were measured before ultrafiltration and on the ultrafiltration permeate. The COD of the HMW fraction was considered to be the difference between these two measurements. SummaryEffluents from the chlorine dioxide bleaching of chemical pulps were characterized with respect to high and low molecular weight material, COD, TOC, elemental composition, and carboxylic acid and methyl ester content. A technique was developed for the quantitative estimation of muconic acid-type structures as moities of the high molecular weight material. The method is based on the use of quantitative 13 C NMR and the pH-dependent cyclization of muconic acids in aqueous solution. 20-40 % of the carboxylic acids in the high molecular weight material isolated from bleach plant effluents from three softwood kraft mills were found to exhibit muconic acid-type behaviour. KeywordsMuconic acids Bleaching effluent Nuclear magnetic resonance Fig. 1. Cyclization of a muconic acid to lactones under acidic conditions.Brought to you by |

Hydrogen Peroxide Treatment of Softwood-Derived Poly(Ethylene Glycol)-Modified Glycol Lignin at Room Temperature

“…Treating lignin derivatives with oxidative reagents, including oxygen, H 2 O 2 , ozone, and peroxy acid, can break down the majority of ether linkages (e.g., β – O –4 linkages) and a portion of C-C linkages through different mechanisms [ 6 , 15 , 21 ]. Additionally, Mc-type structures can be detected through aromatic ring cleavage using 2D HSQC analysis if lignin oxidation occurs under acidic or neutral conditions [ 35 , 37 ]. As reported by Ma et al [ 27 ], the oxidative depolymerization of a lignin model compound through a mild Fenton reaction mechanism using a combination of chalcopyrite (CuFeS2) catalysts with H 2 O 2 in acetate buffer (pH = 2–4) produced DCAs, such as succinic, malonic, and malic acids, due to a ring-opening reaction.…”

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).…”

“…In particular, the successful MATS quantification may be carried out from CH 3 DEPT spectra using methoxy groups as an internal standard (Evtuguin et al 1994). However, the detection of MATS based on the resonance at 51.6 ppm is possible if lignin oxidation occurs under acidic or neutral conditions only because under alkaline conditions methyl esters are readily saponified (Runge and Ragauskas 1999;Vilen et al 2000). Therefore, the detection and quantification of MATS in those cases is impossible.…”