High Molar Mass Lignin in Bleached Kraft Pulp Mill Effluents

Abstract

The proportion of high molar mass (M > 1000D*) substances (HMM) in acid and alkaline bleaching effluents from kraft pulping has been studied by means of analytical gel permeation chromatography, GPC. The amount of HMM substances in alkaline effluents was found to be 65 - 75 % and in acid stage effluents 20 % of the UV-absorbing (A280 nm) components. Lignin is the precursor of the HMM substances in the alkaline stage, and lignin and carbohydrates are the precursors of the acid stage HMM substances. For the purpose of characterization the HMM compounds were separated from low molar mass substances by preparative GPC. The IR spectra of both alkaline and acid stage substances in their neutral form had strong bands characteristic of carboxylic salts. There were no aromatic bands in the spectra of softwood HMM substances. In the spectra of hardwood substances a narrow aromatic band of low intensity was found in two alkaline stage HMM samples originating from mills using a high proportion of ClO2 to chlorine. Elemental analysis of the alkaline stage HMM substances showed that the chlorine content was as high as 9.8 % when the ClO2 charge had been small and less than 4 % with a large ClO2 charge. The low methoxyl group content and high oxygen content showed that the substances were largely oxidized. The LC50 test with water flea indicated no acute toxicity.

Effect of biological treatment on halogenated organics in bleached kraft pulp mill effluents studied by molecular weight distribution analysis

“…This favorable development is to an important part based on the operation of biological treatment plants that are now operative at 13 of the 15 mills (3). Also, process changes have already resulted in substantially It is commonly thought that the major reason for the recalcitrance is the large molecular size of the organic halogen compounds, termed chlorolignins, said to account for up to 80% of the AOX (15,17). It is also thought that chlorinated organic matter is more recalcitrant to biodegradation than are nonchlorinated compounds.…”

A polar high molecular mass constituent of bleached kraft mill effluent is toxic to marine organisms

“…The SEC-HPLC conditions were devised such that the calibration curves of two very different polar macromolecular substances, proteins and polysaccharides, came the closest to each other. These standards were chosen for their polyionic and hydrogen-bonding properties as well as low aromatic content, which are all characteristics expected of the more polar high molecular mass constituents from kraft mill effluents (26)(27)(28). In addition, the chromatogram of Figure 4 was generated at the absorbance maximum of the retentate fraction (208 nm).…”

A new perspective (sorption/desorption) on the question of chlorolignin degradation to chlorinated phenolics

“…to completion under the much more aggressive reaction conditions encountered in the alkali extraction stage of pulp bleaching, namely, temperatures of 50-60 °C, relatively high alkali content (final pH [10][11], and a residence time of 1-1.5 h.…”

“…This paper is one of a series which study the binding of the polar herbicide atrazine (AT) and its hydrolysis product hydroxyatrazine (ATOH), first by the acid-soluble fraction of soil organic matter known as fulvic acid (1), second by the base-soluble fraction known as humic acid (2), and finally by the whole soil. This sequence of studies has been motivated by the widely accepted view (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) that organics play a major role in pesticide binding and transformation in soils. It is anticipated that mechanisms exploited by organic matter in soil can be elucidated by proceeding from the case of a dissolved one-dimensional polyelectrolyte (fulvic acid, FA), through the case of a three-dimensional colloidal gel particle (humic acid, HA), to the case of the whole soil.…”