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Nine phenol derivatives, p-coumaric acid (PC), vanillin (V), acetovanillone (AV), acetosyringone (AS), syringaldehyde (SA), coniferaldehyde (CLD), ferulic acid (FRC), sinapic acid (SNC), and sinapyl aldehyde (SLD) were assayed as laccase redox mediators in the biobleaching of kenaf and sisal pulps. As a general behaviour, the phenolic mediators increased the kappa number (KN) and reduced the brightness of pulps. In particular, these changes were found to depend in a linear manner on the energy of the highest occupied molecular orbital (EHOMO) of the mediators. The phenolic mediator with the lowest EHOMO (PC) led to the highest increase of KN and the lowest reduction of brightness. On the contrary, syringyl derivatives (i.e. SA) with high EHOMO values caused small KN increases and significant losses of brightness. This behaviour was explained on the basis of a competition between grafting and polymerisation processes. The former basically affects KN, whereas the latter affects pulp brightness.

Lignocellulosic crops like kenaf, flax and hemp have been extensively studied the last years with the help of new technology and many new products fabricated with them are ready for the market or have already been marketed. Both the core material and the bast fibers of these crops are ideal feedstocks for the production of yarns and paper of high quality, for rendering flame retardant properties to composites reinforced with them, for the production of energy via a sustainable way without polluting the environment and for use as alternative materials to wood for the manufacturing of panels like particleboards and fiber boards (MDF, HDF, etc.). The investigation of lignocellulosic feedstock as potential source for the sustainable production of materials, products and energy has resulted in promising solutions for the successful replacement of their counterparts made from fossil raw materials. However, the related industries still have some challenges to face, like the cost of materials from lignocellulosic plants in comparison with those derived from fossil sources and the availability of the feedstock throughout the year.

Изучен химический состав стеблей кенафа и сорго сахарного. Установлено, что стебли исследуемого растительного сырья по сравнению с лиственной древесиной содержат меньше лигнина, больше минеральных и экстрагируемых водой веществ. Исследован щелочно-сульфитно-спиртовый способ получения из стеблей кенафа и сорго сахарного волокнистых полуфабрикатов для производства картонно-бумажной продукции. Показана возможность отбелки органосольвентной целлюлозы из стеблей кенафа и сорго сахарного пероксидом водорода без использования хлорсодержащих соединений. Экспериментально подтверждена возможность использования недревесных органосольвстых волокнистых полуфабрикатов в композиции бумаги для печати, картона для плоских слоев гофрированного картона и бумаги для гофрирования., Chemical composition of kenaf and sugar sorghum was studied. It was established that the stems of the investigated plant raw materials in comparison with hardwood timber contain less lignin, more mineral and water soluble substances. Alkali-sulfite-alcohol method of obtaining pulp from kenaf and sugar sorghum stems for producing paper and paperboard. The possibility of bleaching organosolvent pulp from the kenaf and sugar sorghum stems by hydrogen peroxide without the use of chlorine-containing compounds was shown. The possibility of using non-wood organosolvent pulp in the composition of printing paper, cardboard for flat layers of corrugated cardboard and paper for corrugating was experimentally confirmed.

Bleached kenaf handsheets sized with different polymers such as chitosan, polyvinyl alcohol and cationic starch, were used for the determination of surface topography. A non-contact profilometer, the AltiSur ® 500, was used to characterize the topography of structural details in the paper surface. Numerical and visual characterization of surface roughness indicated that the surface of chitosan-sized paper was less rough than other surfaces, and all the sized papers were commonly smoother than the unsized paper. One property of bio-polymer of chitosan is its ability to form films that improve the surface properties of paper when it is applied to the surface of the sheet.

Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, P.O. Box 1052, 41080-Seville, Spain; E-mail address: delrio@irnase.csic.es (J.C. del Río), The chemical composition of lignin and lipids of bast fibers from kenaf (Hibiscus cannabinus) used for high-quality paper pulp production was studied. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of fibers showed a lignin with high syringyl:guaiacyl ratio (5.4) and minor amounts of p-hydroxyphenyl units. Simultaneously, sinapyl and coniferyl acetates were also identified, indicating that this lignin is partially acetylated. p-Hydroxycinnamic acids were only found in trace amounts. The main lipids identified by GC/MS of extracts from kenaf fibers were series of long chain n-fatty acids, waxes, n-alkanes and n-fatty alcohols. Free and esterified sterols and triterpenols, steroid hydrocarbons, steroid and triterpenoid ketones, as well as steryl glycosides were also found. Finally, the fate of the main constituents of kenaf fibers in alkaline pulping was also investigated., This study has been supported by the Spanish Ministerio de Ciencia y Tecnología (MCyT) and FEDER funds (project AGL2002-00393). A.G. acknowledges a "Ramón y Cajal" contract of the Spanish MCyT. We thank CELESA (Tortosa, Spain) for providing the kenaf and pulp samples, S. Camarero (CIB, CSIC, Madrid) for Klason lignin and hemicellulose analyses and A. T. Martínez (CIB, CSIC, Madrid) for critical reading of the manuscript.

The objectives of the tasks of Agrotechnology & Food Innovation (formerly ATO) in the project are: to determine at laboratory level the best conditions for producing high-yield pulps from whole jute for utilisation in wood containing papers; to test the potential of using recommended enzyme recipes in both extruder and refiner processes in terms of pulp quality, chemicals and energy consumption, brightness and production cost; to evaluate the potential of a micro-biological pre-treatment with selected strains of fungi; to establish process conditions for pilot confirmatory trials.

Soda-anthraquinone (soda-AQ), alkaline sulphite-anthraquinone (AS-AQ) and alkaline sulphite-anthraquinone-methanol (ASAM) pulping of date palm rachis and leaves from Sudan was carried under different conditions, and pulps with variable yields and mechanical properties were obtained. The date palm rachis gave best yields and mechanical properties with the AS-AQ or the ASAM process, while the leaves were best pulped with the soda method with low yield, but very good strength properties. Blending with 10% and 30% kenaf bark pulp was beneficial, especially for the AS-AQ pulps. Totally chlorine free (TCF) bleached rachis pulps were obtained of high brightness and strength properties suitable for use in writing and printing papers.

The pulp and paper industry around the world has been growing rapidly. As a result there has been a huge demand for pulp and paper making raw material. Recent years have seen a spurt in use of nonwood fibers being used as a raw material for this purpose. Although some of the nonwood fibers used for papermaking are used because of their fine paper making qualities, majority of nonwood fibers is used to overcome the shortage of wood fibers. As a result their use is more widespread in countries with shortage of wood. The use of nonwood fibers in pulp and paper industry is fraught with problems. Right from supply of raw material to the properties of finished paper, majority of nonwood raw material has proven to be economically inferior to wood. But over the last few years, technological breakthrough in almost all the fields of papermaking have made nonwood more competitive with wood as a raw material for papermaking. Although till recently, use of nonwood fibers for pulp and paper making was concentrated in countries with limited wood supply, it is now showing an increasing trend even in countries with adequate wood supply due to environmental considerations. With time this trend can be expected to grow further and it can be safely said that the future of nonwood plant fibers as pulping and papermaking raw material looks bright. Master of Forestry