Size-exclusion chromatographic study of ECF and TCF softwood kraft pulp bleaching liquors

Abstract

Our liquor samples were studied by using a UV detector commonly used for lignin preparations; in upcoming investigations, it will be interesting to determine carbohydrates such as hemicelluloses. The results are applicable in papermaking in order to improve commonly used bleaching procedures, to test new potential bleaching systems, and to study chemical behavior of HMW materials in various bleaching liquors. The present results also form a good basis for toxicity measurements of ECF and TCF bleaching effluents and for more comprehensive spectroscopic and chromatographic experiments with samples taken from various bleaching stages. From the behavior of liquors studied, it appears that our other structure investigations by spectroscopic and chromatographic (NMR, Py-GC/MS, etc.) methods mostly correlate well with the present results.

Refractory organic pollutants and toxicity in pulp and paper mill wastewaters

“…However, chlorinated phenolics and chlorinated lignin derivatives are the chemicals mostly responsible for the toxicity of pulp and paper effluents. Chlorinated phenolics represent only 2 % of organically bound chlorine in bleaching effluents but are large contributors to effluent toxicity (Heimberger et al 1988;Kukkola et al 2011). In addition, products of lignin oxidation, such as 1,2-dihydrobenzene, have been identified responsible for the mutagenic properties of pulp bleaching plant effluents (Sponza 2003).…”

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

“…5. Molecular structures of two chlorinated phenolsEven though chlorinated phenolics represent less than 2% of the organically bound chlorine in bleaching effluents, they are large contributors to effluent toxicity, carcinogenicity, and mutagenicity (Savant et al 2006;Kukkola et al 2011). The majority of organochlorinated compounds present in pulp and paper mill effluents are HMW chlorolignins (>1 kDa).…”

Dissolved and Colloidal Substances (Dcs) and the Charge Demand of Papermaking Process Waters and Suspensions: A Review

“…) Neimo 1993; Nikkinen et al 2001 Other oxidative bleaching methods (e.g. oxidation of carbohydrates) Ristolainen & Alén 1998;Sjöström et al 2006;Cadena et al 2009;Kukkola et al 2011 Wet-end additives, e.g. dyes, dispersants Medvecz 1993;Hubbe 1999;Hubbe 2007b Recycling, including the de-inking of recovered paper Holmbom 1997;Eisenschmid and Stetter 1998;Mou and Qin 2006;Li et al 2008;Miao et al 2010 * For a fuller selection of cited references, please refer to later sections in this article; only some key references are cited here.…”

“…Furthermore, kraft pulping conditions are sufficiently intense that much of the released hemicelluloses and pectins may be broken down into monomeric species (Vu et al 2003;Rautianen and Alén 2010). Hemicelluloses and pectins also tend to get released during bleaching of kraft pulps (Ristolainen and Alén 1998;Kukkola et al 2011). Work reported by Silvestre et al (2000) and Feng et al 2002; showed that although there are many carboxylated species present among the carbohydrate byproducts in black liquor samples, most such species are monomeric, and only a few have as many as two carboxyl groups per molecules; thus, such species would not be expected to contribute significantly to cationic demand.…”

“…Phenolic groups are not expected to contribute to cationic demand in papermaking applications, since the pK a of such groups is about 10, well above the pH range used in paper formation. Kukkola et al (2011) considered the release of lignin-related materials from softwood kraft pulps subjected to various different bleaching sequences. It was found that the highest molecular mass material tended to be solubilized by peroxide and chelating stages, whereas the lowest molecular mass materials were solubilized in the presence of strong oxidants such as chlorine dioxide and ozone.…”