Browsing by Author "Ni Y."
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Scopus Characterization and evaluation of Paulownia elongota as a raw material for paper production(2008-11-19) Ates S.; Ni Y.; Akgul M.; Tozluoglu A.Paulownia elongota, one of the most fast growing species of the world, was evaluated as raw material for pulp and paper production. The chemical, morphological and anatomical aspects of paulownia wood were determined. The lignin, holocellulose and α-cellulose contents in P. elongota wood were comparable to those of some common non-wood and hardwood raw materials. Different chemical pulping procedures were applied to P. elongota wood to evaluate its pulping potential. Paper strength properties and acidic group content bound to the cell wall were determined. The alkali solubility, water solubility and alcohol-benzene extractive content were higher than those from wood and most nonwoods. The fiber length of 0.83 mm was observed, which is close to low end of the hardwoods but fiber diameter was very wide, similar to that of softwoods. The pulpability of paulownia wood was also studied. The pulp yield and viscosity were very low and the kappa numbers were high. The strength properties were comparable to those of some wood and non-wood pulps. Although, paulownia pulps are considered as low quality materials, it can be used for paper production when mixed with long fibrous materials. © 2008 Academic Journals.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 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 Fungal pretreatment of wheat straw and its effect on the soda-AQ pulps(2009-01-01) Fatehi P.; Ates S.; Ni Y.In this study, the effects of Ceriporiopsis subver-mispora (C.S.) and Phlebia subserialis (P.S.) fungal pre-treatments of wheat straw on the pulp and paper properties of soda-AQ pulps were investigated. The results showed that both fungal pretreatments enhanced delignification and carbohydrate degradation. Also, the P.S. pretreatment increased the brightness and decreased the kappa number and viscosity of pulps more than the C.S. pretreatment. Generally, the bulk, brightness, and tear index of papers increased by the fungal pretreatments, while the tensile and burst indices decreased at all refining levels applied. The C.S. pretreatment had more pronounced effect than the P.S. pretreatment on increasing the bulk and decreasing the tensile and burst indices. Furthermore, cationic-modified poly(vinyl alcohol), CPVA, was used as a dry strength additive to compensate for the loss in the strength properties. The results showed that, upon similar CPVA adsorption, the strength properties of the papers made of the C.S. pretreated fibers were improved more than those of the P.S. pretreated fibers. The application of CPVA on unrefined or refined fungal pretreated fibers showed the possibilities of decreasing the basis weight of papers to achieve the same tensile strength.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.