نوع مقاله : مقاله پژوهشی
نویسندگان
گروه مهندسی پالایش زیستی، دانشکده مهندسی فناوریهای نوین، پردیس زیراب، دانشگاه شهید بهشتی، مازندران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
Introduction:
Nowadays, pulp and paper industries, due to limitations in raw material supplying, Inefficiencies in achieving the system of producing multiple valuable products, the loss of large portion of raw material during processing, and also restriction of the use of the fossil fuel regard to sustainable development, should be addressed the development and reform of efficient methods such as bio-refinery. Bio-refinery by using various pre-treatment methods, changed raw material to its fractions to obtain intermediate products such as sugars (glucose and xylose) that they are changeable to bio-based products with high value-added in the next step. By Bio-refinery approach and to evaluate of potential of the most important papermaking industrial waste, this study carried out by focusing on xylan valuable hemicellulose extraction for production of high value-added products.
Materials and methods:
After the first preparation of bagasse pith, its chemical compounds were determined according to standard methods. For easy obtain to better quality and quantity of xylan, bagasse pith treated by two process of alkali pre-treatment (soda cooking with 2, 4, 6 and 8% alkali concentration, time of 5 and 15 minutes and temperature of 110 , 140 ˚C) and bleaching with sodium chlorite and then evaluated in term of yield and lignin content. Bleached pulps in order to xylan extraction treated with NaOH in different dosages (8, 10 and 14 %). Extracted samples characterized in weight loss, recovery rate, xylan extraction percent as well as FT-IR spectroscopy.
Results and discussion:
Results showed that there is 26% of xylan and 20% of lignin in chemical compounds of the un-treated bagasse pith. In the first processing of bagasse pith, conditions of 8% concentration for NaOH, extraction time 5 minutes and temperature of 110 ˚C were selected due to more yield and less lignin of pulps as well as 6-step process in the bleaching part due to more holocellulose and less lignin. It showed that delignification (alkali cooking) led to lignin removing as well as facilitating of the hemicellulose extraction. Hence, it can be expected improve of the xylan extraction with alkali extraction. In the xylan extraction section, by increasing of NaOH consumption from 8 to 14 percent, the recovery rate of xylan increased to 22 % so that in this conditions extracted xylan content was 4.53 g. FT-IR spectra were also confirmed that with alkali pre-treatment and bleaching, lignin decreased, by increasing in NaOH consumption, xylan extraction was increased and of course, major hemicellulose in bagasse pith is xylan.
Conclusion:
Bagasse pith is reach of 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 suggested as the optimized extraction due to the most yield and extracted xylan percent. Hence, it can used to produce bio-based products in bio-refinery concept.
کلیدواژهها [English]
)