Browsing by Author "Atik C."
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Scopus Comparison of different chemical pulps from wheat straw and bleaching with xylanase pre-treated ECF method(2008-01-01) Ateş S.; Atik C.; Ni Y.; Gümüşkaya E.Different pulping processes, kraft-anthraquinone (AQ), bio-kraft, soda-AQ, ALCELL, and FORMACELL were studied for wheat straw. Fungal pre-treatment with Ceriporiopsis subvermispora, white rot fungi, was applied to wheat straw before kraft-AQ pulping, the so-called bio-kraft process. Fiber properties, carbohydrate contents, FT-IR analyses, strength properties of resultant paper, and bleachability characteristics were included to determine the properties of these pulp samples. In addition, the effects of the xylanase pre-treatment on the subsequent Elemental Chlorine Free (ECF) bleaching process were investigated. The results indicated that kraft-AQ pulps from wheat straw exhibited better characteristics than the other pulp samples with lower kappa number, higher carbohydrate content, higher paper strength properties, and better bleachability. The highest kappa number, viscosity, and fiber coarseness were found for organosolv pulp samples; however, these pulps had the lowest carbohydrate contents and strength values and poor bleaching properties. It was concluded that the fungal pre-treatment of wheat straw with C. subvermispora had a positive effect on the bleachability and gave stronger pulp. There was no clear alteration in the crystallinity index of pulp samples based on the FT-IR results. © TÜBİTAK.Scopus Comparison of pulping and bleaching behaviors of some agricultural residues(2014-01-01) Ateş S.; Deniz İ.; Kirci H.; Atik C.; Okan O.T.The present study determines the characteristics of bleaching and beating of annual plants and agricultural waste, which constitute important raw material potential for the pulp and paper industry in Turkey. It also examines the effects of this process on several paper properties. Firstly, chemical contents are determined for each raw material and then evaluated for use in the pulp and paper industry. All raw materials studied are found to be suitable for use in the pulp and paper industry, according to the determined chemical content. Secondly, pulp with different properties is obtained and subsequently pretreated with the enzyme xylanase. It is then bleached using the elementary chlorine-free (ECF) method, utilizing the DEpD bleaching sequence, which is both easy to apply and highly effective. The bleaching behavior of each material is then determined. The highest ISO brightness value of 98.3% is obtained using soda-AQ pulps deriving from rye straw. This is followed by wheat straw (92.0%), reed (88.6%), corn stalks (87.6%), and rice straw (87.5%). Each unbleached pulp sample is beaten at a constant 3000 revolutions PFI (9000 rev. for hemp), and changes in freeness properties are determined. The hardest material to beat is hemp fibers, followed by reed, rye, corn, and cotton stalks. The best beatable pulps are rice straw, tobacco, wheat, sunflower, and barley stalks. Paper sheets from both unbleached and bleached pulps are tested.Scopus Effects of the endoxylanase treatment on fiber characteristics, brightness stability and strength properties of bleached wheat straw pulp(2009-12-01) Ates S.; Ni Y.; Atik C.The pretreatment of soda-anthraquinone (AQ) wheat straw pulp with purified endo-( 1,4)-β-xylanase was studied. Different xylanase dosages (0, 2, 20 and 100 IUg-1) were applied to the pulp before an ECF (Elemental Chlorine Free) bleaching sequence. The fiber characteristics, brightness stability and strength properties of the obtained pulps were determined. The results showed that the fiber characteristics were not significantly affected by the enzyme pretreatment. On the other hand, the xylanase pretreatment lowered the strength properties of the pulp. A slight improvement in lignin removal was observed, thus improving pulp bleachability, the results agreeing with those obtained on wood pulps. Furthermore, higher paper brightness stability was obtained by the xylanase pretreatment, explained by the removal of the metal ions from the pulp samples.Scopus Mass balance of silica in straw from the perspective of silica reduction in straw pulp(2012-08-01) Atik C.; Ates S.The high silica content of wheat straw is an important limiting factor for straw pulping. High silica content complicates processing and black liquor recovery, wears out factory installations, and lowers paper quality. Each section of wheat straw has different cells and chemical compositions and thus different silica content. In this work, the silica content of balled straw samples were examined according to their physical components, including internodes, nodes, leaves (sheath and blade), rachis, grain, other plant bodies, and other plant spikes. Mass distribution of silica was determined by a dry ashing method. Half (50.90%) of the silica comes from leaves, and its mechanical separation will reduce the silica content in wheat straw pulp significantly. Destroying silica bodies by sonication will increase the strength properties of straw pulp.Scopus Pretreatment by ceriporiopsis subvesmispora and phlebia subserialis of wheat straw and its impact on subsequent soda-AQ and kraft-AQ pulping(2008-01-01) Ates S.; Ni Y.; Atik C.; Imamoglu S.Pretreatments of wheat straw with two different lignindegrading fungal cultures Ceriporiopsis subvesmispora and Phlebia subserialiswere carried out and their effects on sodaAQ and kraftAQ pulping were studied. After two weeks of biotreatment of the wheat straw, both fungus were found to be suitable for biochemical pulping. The fungal pretreatment decreased the kappa number by as much as 24% and the unbleached pulp brightness increased by about 7% at a constant yield. Furthermore, the biopretreatment increased the brightness of the fully bleached pulp by about 1 ISO% point. This can apparently reduce the amount of the chemicals used in the bleaching process. The results on the sugar analysis of the pulps showed that in terms of carbohydrate composition, there were no significant differences between the biotreated and control pulps. However, the strength properties of the unbleached and bleached chemical straw pulps decreased slightly after the fungal pretreatment. This is different from reported results that the strength properties of mechanical pulps were improved after the fungal pretreatment. There was no difference of the two whiterot fungal species, Ceriporiopsis subvesmispora and Phlebia subserialis in term of their effect on the strength properties. © 2008 Bucharest University Printed in Romania.