Fate of lipophilic extractives from several non-wood species during alkaline pulping and TCF/ECF bleaching

Abstract

The chemical composition of lipophilic extractives from several nonwoody fibers such as flax, hemp, sisal and abaca, which are used in the manufacture of high quality paper pulps, was thoroughly studied by gas chromatography and gas chromatography-mass spectrometry. The main compounds identified included series of long chain n-fatty alcohols, n-fatty acids, naldehydes, n-alkanes, free and conjugated sterols, and waxes. On the other hand, the fate of these lipophilic compounds was investigated during soda/anthraquinone (AQ) pulping followed by totally chorine free (TCF) and elementary chlorine free (ECF) bleaching, by analysing unbleached and bleached pulps. The amount of most lipophilic compounds present in the raw materials strongly decreased after soda/AQ pulping although other compounds survived cooking. Among the lipophilic extractives that remained in the unbleached pulps after soda/AQ pulping, unsaturated sterols survived TCF bleaching but were removed by ECF bleaching. On the other hand, saturated fatty acids, fatty alcohols and alkanes were still present in both bleached pulps.