Xylan extraction of bagasse pith in a bio-refinery approach

Nowadays, dues to limitations in raw material supplies, the pulp and paper industries face problems in achieving an efficient system for producing multiple and valuable products. Moreover, the loss of a large portion of raw material during processing and restrictions on the use of fossil fuels with regard to sustainable development, need to be addressed through the development and reform of efficient methods such as bio-refinery. By using various pre-treatment methods, bio-refinery breaks down raw material to their parts to obtain intermediate products such as sugars (glucose and xylose) that can be transformed into bio-based products with high value-added at the next step. By using a bio-refinery approach to evaluate the potential of the most important papermaking industrial waste, this study was carried out by focusing on xylan hemicellulose extraction for the production of high value-added products. After the first preparation of bagasse pith, its chemical compounds were determined using the standard methods. For ease in obtaining a better quality and quantity of xylan, bagasse pith was treated with two process of alkali pre-treatment (soda cooking with 2, 4, 6 and 8% alkali concentration for 5 and 15 minutes and at a temperature of 110 and 140 ˚C) and bleaching with sodium chlorite. This was then evaluated in terms of yield and lignin content. For the xylan extraction, the bleached pulps were treated with NaOH in different dosages (8, 10 and 14 %). Extracted samples were characterized by weight loss, recovery rate, percentage of xylan extraction as well as FT-IR spectroscopy. Results showed that 26% of xylan and 20% of lignin in chemical compounds are present in the untreated bagasse pith. During the first processing of bagasse pith, the conditions of an 8% concentration for NaOH, an extraction time of 5 minutes and a temperature of 110 ˚C were selected due to the greater yield and less lignin of the pulps, as well as a 6-step bleaching process in part due to greater holocellulose and less lignin. This showed that delignification (alkali cooking) led to lignin removlg as well as facilitating of the hemicellulose extraction. Hence, it can be expected improve of the xylan extraction with alkali extraction. In xylan extraction, increasing of NaOH consumption from 8 to 14 percent increased the recovery rate of xylan to 22% so that, under these conditions, the extracted xylan content was 4.53 g. FT-IR spectra also confirmed that lignin decreased with alkali pre-treatment and bleaching and, by increasing NaOH consumption, xylan extraction was increased which is, of course, the major hemicellulose in bagasse pith. Bagasse pith is rich in the carbohydrate specific xylan so that its alkali pre-treatment and bleaching led to lignin loss and more accessibility to this carbohydrate. Finally, xylan extraction using 14% NaOH was suggested as the optimized extraction method due to greatest yield and percentage of extracted xylan. Hence, it can used to produce bio-based products in a bio-refinery concept.