industrial crops and products 28 ( 2 0 0 8 ) 11–16 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/indcrop Alternative raw materials and pulping process using clean technologies Luis Jim´ enez * , Alejandro Rodr´ ıguez, Antonio P´ erez, Ana Moral, Luis Serrano Chemical Engineering Department, University of C ´ ordoba, Spain article info Article history: Received 12 September 2006 Received in revised form 28 December 2007 Accepted 28 December 2007 Keywords: Leucaena leucacephala Chamaecytisus proliferus Vine shoots Cotton stalks Pulp Paper Ethyleneglycol abstract In this work, we characterized various unconventional pulping raw materials in terms of their contents in hollocelulose, -cellulose, lignin, ethanol–benzene extractables, ash, and hot water and 1% soda solubles. Also, we characterized pulp obtained from each material by using an ethyleneglycol concentration of 65% at 180 ◦ C for 75 min, followed by beating at 1500 revolutions in a PFI refiner—all of which are compatible with existing facilities for Kraft and soda pulping processes. We characterized vine shoots, cotton stalks, Leucaena leucocephala and Chamaecytisus pro- liferus as pulping raw materials and found Ch. proliferus and cotton stalks to be the best for the intended purpose on the grounds of their increased contents in holocellulose (79.73 and 72.86%) and -cellulose (45.37 and 58.48%), and their decreased contents in ethanol–benzene extractables (2.64 and 1.42%), hot water solubles (2.79 and 3.33%) and 1% soda solubles (16.67 and 20.34%). These properties resulted in increased pulp yields and hence in efficient use of these two types of raw material. The paper sheets obtained of different pulps were characterized and those from Ch. pro- liferus found to be the best overall as they exhibited an increased breaking length (4644m), stretch (2.87%), burst index (2.46 kN/g) tear index (0.33 mN m 2 /g) and brightness (49.92% ISO); in addition Ch. proliferus pulp was obtained with a high yield (62.88%). On the other hand, vine shoots provided the poorest results among the studied raw materials. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Paper usage has grown steadily worldwide over the last few decades. Specifically, the amount of paper used yearly in the world increased from 1.025 × 10 6 to 1.625 × 10 6 tonnes between 1988 and 1998 (Bayer et al., 1999). In Europe an increase of 41.4% has taken place in the consumption of paper from the 1991 to the 2005, spending from 62.387 × 10 6 to 88.213 × 10 6 tonnes (Annual Statistics, 2005). In the period 1995–2002, the paper production in Spain has registered an accumulated growth of 46% (Aspapel, 2006). ∗ Corresponding author. Tel.: +34 957218658; fax: +34 957218625. E-mail address: iq1jiall@uco.es (L. Jim ´ enez). With the inception of new computer-based and audiovi- sual technologies, a gradual decrease in paper consumption was envisaged; rather, the expansion of computers has boosted paper usage (Anuario de Estad´ ıstica and Agrario, 2003). This has raised the worldwide consumption of pulp- wood to 170.358 tonnes in 2003. The environmental problems raised by this increase in wood usage have elicited major technological efforts involv- ing the development of new, faster-growing wood species of higher quality, as well as less polluting cooking and pulp bleaching processes; additional efforts have focussed on recy- 0926-6690/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2007.12.005