|Chlorine-free bleaching of kraft pulp from oil palm empty fruit bunches|
|ساعت ٢:۳۸ ب.ظ روز شنبه ٢۱ دی ۱۳۸٧|
Empty fruit bunches (EFB, Photo 1 : 60KB) are lignocellulosic residues from palm oil production in Malaysia and other tropical countries. Recent attempts to produce pulp for paper-making from EFB by mechanical and chemical pulping mark the first efforts to utilize this potential resource. However, little work has been done on bleaching EFB pulp, especially utilizing the more environmentally friendly chlorine-free bleaching method.
In this study, we carried out chlorine-free bleaching on EFB kraft pulp. The bleaching process employed the application of oxygen (O2), sulfuric acid (H2SO4), ozone (O3), and hydrogen peroxide (H2O2). After bleaching, the
k-number (indicator of lignin content) of the pulp became negligible (Table 1 :58KB), indicating that most of the lignin contained in the pulp can be removed without using chlorine compounds as bleaching agents. Both chlorine-bleached and unbleached handsheets of the EFB pulp were produced and the paper properties were determined as shown in the table. The brightness, a measure of the whiteness of paper, of the bleached pulp handsheets was about 75%. Though this figure is slightly lower than the required brightness of 80% for bleached kraft paper, this result shows a strong possibility of achieving the requisite brightness through chlorine-free bleaching of EFB pulp. Opacity is the ability of paper to hide or mask a color or object. The figure obtained for the bleached handsheet in this study was found to be comparable to that of commercial paper.
Handsheet paper strength, which is indicated by tensile index, stretch, tear index, and burst index, did not change significantly from before and after the bleaching process. Thus, the effects of the bleaching process on handsheet properties are negligible. Moreover, the EFB bleached pulp displayed comparable strength to some hardwood pulps, indicating that EFB has potential to serve as a raw material for chemical pulp through chlorine-free bleaching.