Degradation products of lignocellulosics in pulp mill effluents – comparison and evaluation of different gas chromatographic techniques for a comprehensive analysis

Abstract

Abstract Pulp mill effluents contain potentially valuable compounds and will gain even greater importance than today in future biorefinery scenarios as possible resources. Analysis of effluents of process streams is not straightforward because of the vast variety of substances embedded in the complex inorganic matrix of high concentration. In the present comparative investigation, different combinations of gas chromatography (GC) and derivatisation techniques were tested and critically evaluated aiming at a comprehensive description of all major compound classes (low-molecular weight and long-chain carboxylic acids, lignin fragments, carbohydrates and aldehydes). As derivatisation techniques, trimethylsilylation, (trimethylsilyl)methylation and methylation were applied. In addition, the effluents were analysed by pyrolysis-GC/mass spectrometry (MS), either directly or with simultaneous methylation. The study provides comprehensive information on the composition of effluents, the suitability of the various combinations of derivatisation and GC/MS techniques. The discrimination effects of the different approaches are compared. The comprehensive analytical approach led to a coherent balance in terms of the contribution of the major portion of organic compounds to the total organic carbon (TOC) content in pulp mill effluents.