Lipophilic extractives from nonwood fibers during soda/AQ pulping followed by TCF and ECF bleaching

In this work we report the chemical composition of lipophilic extractives from several nonwood fibers such as flax, hemp, jute, sisal and abaca, which are used in the manufacture of high-quality paper pulps, during soda/anthraquinone (AQ) pulping followed by totally chorine free (TCF) and elementary chlorine free (ECF) bleaching. With this purpose, the lipid extracts from the different raw materials and their unbleached and TCF and ECF bleached pulps were analyzed by gas chromatography and gas chromatography-mass spectrometry. The different lipophilic extractives present in the nonwood fibers analyzed, including alkanes, fatty acids, fatty alcohols, aldehydes, free and conjugated sterols, and waxes, showed a different behavior during pulping and bleaching. The amount of most lipophilic compounds strongly decreased after soda/AQ pulping and esterified compounds such as waxes, ferulates and glycerides were hydrolyzed. 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 TCF and ECF bleached pulps.

This study has been supported by the Spanish Ministerio de Educación y Ciencia (MEC) (project AGL2005-01748 and BIO2007-28719-E) and EU project (BIORENEW, NMP2-CT-2006-026456). We thank CELESA pulp mill (Tortosa, Spain) for providing the samples. G.M. thanks the Spanish MEC for a FPI fellowship.

Peer reviewed