Qualitative analysis of chlorolignins and lignosulphonates in pulp mill effluents entering the river Rhine using pyrolysis-mass spectrometry and pyrolysis-gas chromatography / mass spectrometry

Macromolecular chlorolignins and lignosulphonates have been analysed in effluents from five pulp mills discharging on the river Rhine. Analytical techniques used were ultrafiltration, pyrolysis—mass spectrometry and pyrolysis—gas chromatography / mass spectrometry. The average organically bound chlorine content was 19 mg/l, with a maximum value of 68 mg/l for the pulp mill Cellulose de Strasburg. The annual discharge of organically bound chlorine (AOX) and of dissolved organic carbon (DOC) of these five mills was calculated to be 2100 tonnes AOX and 33 000 tonnes DOC, respectively. This would account for 90% of the AOX load and 10% of the DOC load of the river Rhine. Evidence for the existence of two chlorolignin classes, aromatic chlorolignins and aliphatic chlorolignins, was obtained. Monochloroguaiacol is the most abundant structural specific aromatic chlorolignin pyrolysis product. Methyl chloride is a major chlorine containing pyrolysis product, probably originating from aliphatic chlorolignins. Sulphur dioxide is a major pyrolysis product of lignosulphonates, and possibly can be used for the specific quantitative determination of lignosulphonates in river water. Radical recombination reactions of methyl radicals and other primary pyrolysis radicals play an important role in these samples, leading to several secondary pyrolysis products. The presence of lignosulphonates in the salt or acid form has an important effect on the pyrolysis process. Methyl chloride can probably be quantified with the reference compound tetramethylammonium chloride. The macromolecular compositions of these effluents show many similarities, but also significant differences, presumably reflecting the use of different wood types, pulping and bleaching conditions at the time of sampling.

• View at Publisher