Yazar "Tozluoğlu, Ayhan" seçeneğine göre listele

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    Activated carbon nanotube/polyacrylic acid/stearyl alcohol nanocomposites as thermal energy storage effective shape-stabilized phase change materials
    (Elsevier, 2022) Göksu, Haydar; Aydınlı, Elif; Hekimoğlu, Gökhan; Sarı, Ahmet; Gencel, Osman; Subaşı, Serkan; Tozluoğlu, Ayhan
    Stearyl alcohol (SA) as one of organic phase change materials (PCMs) has promising thermal energy storage prospective. However, the leakage issue during solid-liquid phase change period and low heat harvesting and releasing rate significantly attenuates its TES potential. Towards to overcome these drawbacks, the SA was shape stabilized using the cross-linked poly acrylic acid (PAA) and activated single walled carbon nanotubes (aSWCNTs) at three different weigh ratio of 1:1:2, 1:3:4 and 1:5:6 (a-SWCNTs:PAA:SA). The chemical/crystalline and morphologic structures of the produced shape stabilized-nano composite PCMs (SS-NCPCMs) were investigated by FT-IR, XRD and SEM analyses. The latent heat storage (LHS) features and thermal stability of the SSNCPCMs were measured by DSC and TGA techniques. The thermal cycling effect on the LHS properties and chemical structures of the SS-NCPCMs was also estimated. The DSC findings indicated that the SS-NCPCMs had melting temperature of around 55-56 C and latent heat capacity of about 135 J/g. TGA measurements disclosed that the thermal degradation temperatures of the nano composite PCMs were prolonged somewhat compared to the SA. A 500 heating-cooling cycling test revealed that the SS-NCPCMs had great chemical and LHS stability. The heat harvesting and releasing performance of the NCPCMs were considerably shortened compared to those of pure SA. The obtained results exposed that the synthesized SWCNTs/PAA/SA composites can be evaluated as promising LHS materials for thermal management of electronic systems, automobile modules, food carriers, solar PV panels etc.
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    Alkaline-ethanol pulping of cotton stalks
    (Academic Journals, 2010) Akgül, Mehmet; Tozluoğlu, Ayhan
    In this study, the use of cotton stalks (Gossypium hirsutum L.) as a raw material for papermaking using soda ethanol (organasolv) with/without anthraquinone (AQ) were briefly examined. Yield, kappa number and viscosity were determined for resulting pulps and the hand sheets produced from pulps were tested for physical properties; tensile index, burst index, tear index and elrepho brightness. The obtained results showed that, pulp yield and viscosity of the soda pulp was increased by adding AQ, ethanol and with their combinations. On the other hand, the positive effects that various chemicals (AQ, ethanol, and their combinations) had on the pulp quality were also observed on the paper's physical and optical qualities, and these observed effects were thought of bearing considerable importance for paper manufacturers.
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    Atık sularda boya giderimi için fonsiyonellenmiş nanoselüloz esaslı adsorbanlar
    (2021) Arslan, Recai; Tozluoğlu, Ayhan; Sertkaya, Selva; Fidan, Hakan; Küçük, Sibel
    Son yıllarda, dünya genelinde artan nüfus ile birlikte tarımsal ve endüstriyel faaliyetler giderekartmıştır. Bu faaliyetler sırasında ortaya çıkan organik maddeler, inorganik anyonlar, toksik ağırmetaller, zehirli gazlar vb. birçok kirletici çevreye salınmakta ve özellikle sularda önemli derecedekirlilik sorunlarına yol açmaktadır. Bu nedenle çevre dostu ve uygun maliyetli arıtma teknolojilerineihtiyaç duyulmaktadır. Atık sularda kullanılan adsorpsiyon işlemi çevre dostu arıtma teknolojilerindenbiridir. Çeşitli doğal kaynaklardan elde edilebilen selülozik maddeler adsorbanlar olarakkullanılabilmektedir. Atık sularda bulunan organik kirleticiler ve ağır metal iyonlarının adsorpsiyonkapasiteleri kimyasal işlemlerden etkilenmekte olup, modifiye edilmiş selülozun modifiye edilmemişselüloza göre daha yüksek adsorpsiyon kapasitesi sergilediği bilinmektedir. Bu derlemede, literatürdeyer alan çeşitli nanoselüloz esaslı adsorbanların, özellikle atık sularda bulunan boyalarınuzaklaştırılmasında sergiledikleri adsorpsiyon kapasiteleri ve bu adsorbanların modifikasyonlarısonrasında yapılarının karakterizasyonunda kullanılan FTIR ve SEM analizleri incelenmiştir.Nanoselüloz esaslı adsorbanların atık sulardaki boyaların uzaklaştırılmasında iyi bir potansiyelsergilediği görülmektedir. Çevre kirliliğini minimuma indirmek için ucuz ve daha etkili selüloz esaslıadsorbanların modifikasyonlarla geliştirilebileceği düşünülmektedir.
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    Bioethanol production from common reed (Phragmites australis): Biological and chemical pretreatments
    (Ars Docendi, 2018) Tozluoğlu, Ayhan
    The present study was aimed at examining the feasibility of using common reed for the production of bioethanol by means of biological and chemical pretreatments. The effectiveness of sodium hydroxide (NaOH), hydrogen peroxide (H2O2), sodium borohydrate (NaBH4), boron oxide (B2O3) and sulfuric acid (H2SO4) for conversion of common reed to ethanol was investigated via chemical pretreatments. Fungal pretreatment (C. subvermispora) degraded the reed structure and 10 weeks of incubation time removed 11.3 and 14.0% of glucan and xylan from the structure, respectively. Statistical analysis showed that fungal pretreatment had a significant effect (p < 0.001) on lignin removal. The lignin loss of common reed was 9.16, 10.7 and 16.6% in 2, 4 and 8 weeks, respectively. Chemical pretreatments of NaOH, H2O2, NaBH4, B2O3, H2SO4 dissolved 7.66, 12.2, 4.50, 15.7 and 15.0% of glucan from the structure. The highest xylan dissolution (63.7%) was observed when common reed was pretreated with H2SO4. In addition, NaOH and NaBH4 pretreatments removed 55.8 and 52.0% of lignin, respectively.
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    Bioethanol production from common reed (Phragmites australis): Enzymatic hydrolysis and fermentation
    (Ars Docendi, 2018) Tozluoğlu, Ayhan
    Several biomaterials consisting of high amount of carbohydrate in the structure and pretreatment methods have been studied by researchers to maximize the ethanol yield. Therefore, this study was focused on enzymatic hydrolysis and fermentation of common reed for the bioethanol production. The biologically and chemically pretreated common reed was enzymatically hydrolyzed and the results showed that the NaOH treatment had the highest glucan conversion rates (79.7%), followed by the NaBH4 (74.1%), H2O2 (71.9%), fungal pretreatment (69.4%), B2O3 (65.5%) and H2SO4 (46.1%). The highest ethanol yield (13.2 g/100 g) and the calculated highest theoretical yield (85.3%) from untreated common reed were observed for the NaOH- pretreated samples. The fungal- and NaBH4-pretreated samples yielded 10.6 and 12.3 g/100 g of ethanol (based on untreated common reed), respectively. The results of this study indicated that, because of its economic feasibility and environmental advantages, the fungal pretreatment was more suitable for common reed bioethanol production.
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    Bioethanol production via enzymatic hydrolysis of lignocellulosic bi?omass: Wheat straw, corn stalks and hazelnut husk
    (Düzce Üniversitesi, 2012) Tozluoğlu, Ayhan; Çöpür, Yalçın
    Ülkemiz dünyanın sayılı tarım üreticisi ülkeleri arasında bulunmaktadır. Ekin sapı, mısır sapı ve fındık zurufu atıklarının mevcut potansiyel durumu göz önüne alındığında bu lignoselülozik biyokütlelerin biyoetanol üretiminde değerlendirilmesi önem arz etmektedir. Gelişmekte olan yeni biyoteknolojik yaklaşımlar sayesinde bu tarz yenilenebilir lignoselülozik biyokütlelerden biyoetanol üretimi, çevresel pozitif katkılarının yanı sıra ülke ekonomisini de olumlu yönde etkileyecektir. Bu çalışmada ekonomik değeri düşük/yok olan lignoselülozik biyokütlelerden ekin sapı, mısır sapı ve fındık zurufunun biyoetanol üretiminde kullanım olanakları araştırılmıştır. Ön muamele işlemlerinde kullanılan geleneksel kimyasallara (H2SO4, NaOH, H2O2) alternatif olarak NaBH4 kimyasalı bu çalışmada ilk kez ön muamele amacıyla kullanılmıştır.Elde edilen veriler ekin sapı için değerlendirildiğinde enzimatik hidroliz işleminde NaOH (%87.8) ve NaBH4 (%83.3)'ün H2O2 (%74.7) ve H2SO4 (%71.7)'e nazaran daha etkin oldukları ve daha yüksek oranda glukan-glukoz dönüşümü sağladıkları gözlemlenmiştir. En yüksek etanol verimi (115 g/kg ekin sapı) %4 NaBH4 ile 60 dak süreyle muamele edilen örnekte belirlenmiş olup teorik verim aynı örnek için %86.9 dur.Mısır sapında NaOH (83.9%) ve NaBH4 (82.9%) enzimatik hidroliz işleminde en yüksek glukan-glukoz dönüşümü ortaya koymuş olup, en yüksek etanol verimi (97.4 g/kg mısır sapı) mısır sapı % 4NaBH4 ile 90 dak süre ile muamele edildiğinde belirlenmiştir. Bu örnek için teorik verim değeri %72.5 tir.Fındık zurufu için yapılan çalışmalarda ise NaBH4'ün en yüksek miktarda yapıdan lignini uzaklaştırdığı belirlenmiş ve NaOH ve NaBH4'ün H2O2 ve H2SO4'e nazaran daha seçici lignin delignifikasyonu sağladıkları tespit edilmiştir. Enzimatik hidroliz işleminde en yüksek glukan-glukoz dönüşümü (%74.4) ve en yüksek etanol verimi (52.6 g/kg fındık zurufu) örnekler %2 NaOH ve 90 dak süre ile muamele edildiğinde gözlemlenmiş olup bu örnek için teorik verim değeri %72.6 olarak belirlenmiştir.Numuneler kendi aralarında karşılaştırıldığında ekin sapının biyoetanol üretimi için kullanımının daha uygun olduğu görülmektedir. Ayrıca kimyasal ön muamelelerde NaOH ve NaBH4'ün etkin oldukları görülmektedir.
  • Küçük Resim Yok
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    Biofilms from micro/nanocellulose of NaBH4-modified kraft pulp
    (Indian Acad Sciences, 2017) Tozluoğlu, Ayhan; Poyraz, Bayram; Candan, Zeki; Yavuz, Mustafa; Arslan, Recai
    Industrial applications of microfibrillated cellulose (MFC) and nanofibrillated cellulose (NFC) have been in use for some time; however, there is a need to improve the production steps and at the same time to obtain better quality products. NFC and MFC were generated from -modified kraft pulp, produced from a red gum tree plant (Eucalyptus camaldulensis). The generated NFC and MFC were characterized by high-performance liquid chromatography, Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and -nuclear magnetic resonance (NMR). Morphological and viscoelastic properties were investigated by scanning electron microscopy and rheometry, respectively. The storage moduli of biofilms produced from NFC and MFC were investigated by dynamic mechanical thermal analysis (DMTA). Both exhibited mostly identical FTIR spectra. When the spectra were compared with those of -modified kraft pulp, minor shifts were observed due to crystallinity. In NMR spectra, disordered cellulose structures were observed for both NFC and MFC, and these findings were also confirmed by differential scanning calorimetry. Rheology studies revealed that the lowest viscosity was observed with MFC. TGA results showed that NFC degraded earlier compared with -modified kraft pulp. DMTA exhibited that NFC films had about six times higher storage modulus compared with MFC.
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    Biyoliflendirme işleminde farklı beyaz çürüklük mantarlarının ve inkübasyon sürelerinin odunun kimyasal bileşimi üzerine etkisi
    (2024) Tozluoğlu, Ayhan; Arslan, Recai
    Kâğıt hamuru üretiminde yüksek enerji ve kimyasal madde tüketimi gibi olumsuz etkilerin bertaraf edilmesi amacıyla son yıllarda geliştirilen alternatif yöntemlerden birisi de biyoteknolojik uygulamaların bu sektörde kullanılmaya başlanmış olmasıdır. Bu yöntemde odun yongaları beyaz çürüklük mantarları ile muamele edilmekte ve böylece ligninin ön delignifikasyonu sağlanarak daha çevreci bir yöntemle kâğıt hamuru üretimi gerçekleştirilebilmektedir. Biyolojik kâğıt hamuru üretimi (biyoliflendirme-biopulping) adı verilen bu alternatif modifiye yöntem sayesinde odunda bulunan ligninin bir kısmı beyaz çürüklük mantarlarının biyolojik degradasyonuyla yapıdan uzaklaştırılmaktadır. Çalışmamızda beyaz çürüklük mantarlarından aktif delignifikasyon etkisine sahip Phanerochaete chrysosporium, Pleurotus ostreatus ve Ceriporiopsis subvermispora mantarları ile karaçam yongaları aşılanmak suretiyle biyolojik ön uygulama gerçekleştirilerek, biyolojik modifikasyon işlemlerinin odunun kimyasal bileşimi üzerindeki etkisi özellikle ligninin delignifikasyonu dikkate alınarak değerlendirilmiştir. Mantar muamelesi sonrasında en hızlı ağırlık ve lignin kaybının 4. hafta sonunda gerçekleştiği belirlenmiştir. İnkübasyon süresine bağlı olarak mantar muamelesi sonrasında odundaki diğer bileşenlerin azalmasına bağlı olarak holoselüloz miktarları oransal olarak artış göstermiştir. Optimum inkübasyon süresinin belirlenmesi noktasında odunun kimyasal bileşimi üzerinde yapılan çalışmalara bağlı olarak P. chrysosporium için 4 hafta; P. ostreatus ve C. subvermispora için ise 6 haftalık inkübasyon sürelerinin optimum olduğu belirlenmiştir.
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    Cellulose and lignin in place of EPDM and carbon black for automotive sealing profiles
    (Elsevier B.V., 2023) Poyraz, Bayram; Güner, Yusuf; Tozluoğlu, Ayhan; Aslan, Recai
    This study aims at using microcrystalline cellulose (MCC) and lignin in place of EPDM and carbon black with specified amounts to investigate the chemical, thermal, rheometric, mechanical, thermo-aging and morphological properties of EPDM elastomers. At the end of the study, the introduction of the MCC and lignin enabled higher elastic modulus and tear strength unlike tensile strength by revealing minor chemical shifts and lower thermal stability. In addition, the MCC and lignin facilitated the vulcanization process with fewer torque values by dispersing mostly homogeneously in the matrix. It was shown that all of the mechanical values were found to be in the range of the specified standard after the replacement of the MCC and lignin. © 2023 Elsevier B.V.
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    Cellulosic Bioethanol Production Technology
    (Düzce Üniversitesi, 2011) Çöpür, Yalçın; Tozluoğlu, Ayhan; Özyürek, Ömer
    Increase in consumption ofenergy paralel to increased population, environmental issues and danger ofdepletion of present energy sources forces countries to renewable resources toproduce clean energy. Instead of fossil based energy sources, renewablebioresources especially agricultural wastes to produce bioethanol is veryimportant for the energy sector and country’s economy. Using annual plants andagricultural wastes in energy sector expected to diminish the pressure onnatural forests and fill the raw material gap in production. nbsp;
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    Characterization and evaluation of Paulownia elongota as a raw material for paper production
    (Academic Journals, 2008) Ateş, Saim; Ni, Yonghao; Akgül, Mehmet; Tozluoğlu, Ayhan
    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 -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 non-woods. 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.
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    A comparison of kraft, PS, kraft-AQ and kraft-NaBH4 pulps of Brutia pine
    (Elsevier Sci Ltd, 2008) Çöpür, Yalçın; Tozluoğlu, Ayhan
    The aim of this work was to study the effect of adding PS, AQ and NaBH4 into kraft pulping with special attention given to NaBH4. Kraft, kraft-AQ, PS, and kraft-NaBH4 Pulps were produced under the same cooking conditions and the pulps produced were compared in terms of pulp and paper properties. Kraft method was modified by adding 0.1% AQ, 4% PS and 2% and 4% NaBH4 and the resultant pulps displayed an increase in pulp yield and reduction in both kappa number and screening rejects. On the other hand, there observed an increase in both pulp yield and kappa number when the kraft was modified to PS method. The benefits of NaBH4 addition into kraft pulping was a significant reduction in kappa number and screening rejects and a significant increase in pulp yield. The most notable outcome of NaBH4 was 66.6% increase in pulp brightness when 4% NaBH4 was added into kraft pulping. Of unrefined pulps, unrefined kraft pulp displayed the highest strength of pulp, which is described as tear index at a constant tensile index. Of refined pulps, kraft-AQ showed the highest pulp strength when refined to 6000 and 12,000 revs in PFI mill. (c) 2007 Elsevier Ltd. All rights reserved.
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    A comparison of soda and soda-AQ pulps from cotton stalks
    (Academic Journals, 2009) Akgül, Mehmet; Tozluoğlu, Ayhan
    In this study, cotton stalks (Gossypium hirsutum L.) were cooked using soda and soda-anthraquinone (AQ) process. Nine soda cooks were conducted by changing cooking conditions including active alkali charge and pulping time. Soda-AQ cooks were obtained by adding 0.075, 0.10, 0.15, 0.2% AQ (based on o.d stalks) to optimum soda pulping. Adding AQ to soda pulps led to the increase in regarding to pulp yield and kappa numbers. On the other hand, soda-AQ pulps made from cotton stalks showed higher mechanical properties than soda pulps. The results indicated a major increase in pulp brightness when soda pulping was modified with %0.15 AQ. Also, the results showed that better pulp and paper can be produced from cotton stalks by soda-AQ process compared to the soda process.
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    Determination of wood characteristics of Pinus brutia Ten. infested with Marchalina hellenica Genn.
    (Taylor & Francis Ltd, 2022) Arslan, Mustafa Burak; Avci, Erkan; Tozluoğlu, Ayhan; Birtürk, Turgay; Saracbasi, Akin; Özcankaya, İ. Meltem; Koçer, Nihan
    The aim of this study was to examine the chemical, anatomical, physical, and mechanical properties of Marchalina hellenica Genn.-infested Pinus brutia Ten. wood. Studies were carried out on wood samples taken from uninfested trees, those with low M. hellenica infestation, and those with high infestation. In the P. brutia wood heavily infested with M. hellenica, statistically significant decreases were found in the holocellulose and alpha-cellulose ratios, the tracheid number in latewood, the growth ring width in earlywood and latewood, and the density and strength values. However, the density arid strength values of the P. brutia wood samples that were not infested and those with low M. hellenica infestation did not statistically differ from one another.
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    DEVELOPING NANOCELLULOSE-BASED BIOFILMS FROM KRAFT AND NaBH4 - MODIFIED KRAFT PULP
    (Editura Acad Romane, 2018) Tozluoğlu, Ayhan; Poyraz, Bayram; Mcdonald, Armando G.; Candan, Zeki
    In this study, both kraft pulp and NaBH4-modified kraft pulp produced from the red gum tree (Eucalyptus camaldulensis) were used to generate nanofibrillated cellulose (CNF) and microfibrillated cellulose (CMF). These were then characterized by HPLC, FTIR, DSC and C-13-NMR. Morphological and viscoelastic properties were investigated via SEM and rheometry, respectively. The storage moduli of the biofilms produced from the CNFs were investigated by dynamic mechanical thermal analysis (DMTA). Some minor shifts were observed in the 13C-NMR for the CMF and CNF obtained from NaBH4-modified kraft pulp. The CMF and CNF obtained from kraft pulp revealed higher thermal stability due to higher crystallinity. Higher dynamic mechanical properties were seen in the CNF film obtained from kraft pulp and the results were useful in ascertaining its potential application value.
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    The effect of AQ and NaBH4 on bio-kraft delignification (Ceriporiopsis subvermispora) of brutia pine chips
    (Elsevier Sci Ltd, 2007) Çöpür, Yalçın; Tozluoğlu, Ayhan
    Brutia pine wood chips were pretreated with lignin degrading fungus (Ceriporiopsis subvermispora) and its effects on kraft pulping involved adding antraquinone (AQ) and NaBH4 into the white liquor were studied. The results showed that pulp rejects were lower for biokraft pulp and a significant reduction was observed when biokraft process was modified by NaBH4 compared to the control kraft method. Also, an increase on pulp yield and reduction on kappa number was noticed with biokraft pulp. Adding AQ and NaBH4 into biopulping led to positive results with regards to pulp yield and kappa number compared to biokraft pulp. The results indicated a major increase in pulp brightness when biokraft pulping was modified with 2% NaBH4. On the other hand, biopulps gave lower tear but higher burst index compared to the control kraft pulp. Tensile index of the biopulps were slightly lower; however, untreated kraft pulp was found to be easier to refine and when pulps were refined to 12,000 revs. in PFI mill, biokraft-AQ pulp showed a significant improvement on tensile index. (C) 2007 Elsevier Ltd. All rights reserved.
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    THE EFFECTS OF BORON DERIVATIVES AS PRETREATMENT CHEMICALS FOR BIODEGRADATION OF SUNFLOWER STALKS
    (Univ Bio-Bio, 2016) Tozluoğlu, Ayhan
    This study examined the suitability of boron derivatives as pretreatment chemicals with regard to their efficiency in the enzymatic saccharification of sunflower stalks. It was hypothesized that the utilization of boron derivatives might improve enzymatic digestibility. The aim of this study was to examine the effect of NaOH and the boron derivatives sodium borohydride [NaBH4], calcined tincal [Na2B4O7(1-5)H2O], colemanite [CaB3O4(OH)(3)H2O], boron oxide [B2O3], borax decahydrate [Na(2)B(4)O(7)10H(2)O], disodium octaborate tetrahydrate [Na(2)B(8)O(13)4H(2)O] and boric acid [H3BO3] on enzymatic saccharification. Results showed that the boron derivatives prevented peeling reactions and preserved more glucan; however, the NaOH removed the highest amounts of xylan and lignin from the structure. Significant xylan removal was observed with H3BO3, while B2O3 was as effective as NaBH4 and NaOH for selective lignin removal. The highest enzymatic saccharification yield (59,5%) resulted with the 2% NaOH pretreatment, whereas slightly lower yields were achieved with some boron derivatives (1% NaBH4-45%; 2% B2O3-40,2%; and 2% H3BO3-36,7%).
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    Effects of cellulose micro/nanofibers as paper additives in kraft and kraft-NaBH4 pulps
    (Walter De Gruyter Gmbh, 2016) Tozluoğlu, Ayhan; Poyraz, Bayram
    This study examined the effects of various CMF/CNFs (microfibrillated and nanofibrillated celluloses) on the relevant properties of paper produced from kraft and kraft-NaBH4 pulps. Subsequent effects of pretreatments on the mechanical, drainage, optical and physical properties of papers obtained from both kraft and kraft-NaBH4 pulps were also studied. Enzymatic pretreatments were accomplished using Celluclast 1.5 L and Pulpzyme HC 2500 enzymes; 2,2,6,6-tetramethyl-l-piperidinyloxy (TEMPO), phthalimide-N-oxy (PINO) and periodate were utilized in chemical pretreatments. Results showed that the mechanical properties of paper for both kraft and kraft-NaBH4 pulps were improved with the addition of different types of CMF/CNF samples, whereas the sheet drainage was impaired. With 1.5% additions of various CMFs, the kraft pulp and the kraft-NaBH4 pulp displayed increases of 8.32-18.3% and 2.33-8.86% in tensile strength and 6.00-14.0% and 14.0-22.0% in degrees SR, respectively. Compared to other pretreated CMF/CNFs, periodate oxidized-CMF/CNFs significantly affected the properties of papers obtained from both kraft and kraft-NaBH4 pulps. Results also showed that the addition of various CMF/CNFs had a greater effect on the kraft-NaBH4 pulp than on the kraft pulp.
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    Enzimatik Ağartma İşlemlerine Genel Bir Bakış
    (Düzce Üniversitesi, 2006) Akgül, Mehmet; Tozluoğlu, Ayhan
    Enzimler, ilk olarak yiyecek ve içeceklerin üretim aşamalarında, giysilerin temizlenmesinde, hastalıkların teşhisinde kullanılmaktadır. Nihayet hayatımıza büyük ölçüde girmiş olup, enzim kullanabilecek en büyük alanlardan biri de selüloz ve kağıt endüstrisi olarak bildirilmektedir. Özellikle kağıt hamurunun ağartılmasında bilinen geleneksel yöntemlerin sahip oldukları dezavantajlar onların kullanımını sınırlamakta ve çevre dostu üretim prosesleri daha da önem kazanmaktadır. Artan hamur verimi yanında gelişen lif özellikleri ve azalan çevre problemleri kağıt endüstrisinde enzim kullanılmasını doğuran başlıca nedenler olmuştur. Kağıt endüstrisinde enzim kullanımının etkisini daha iyi anlayabilmek amacıyla çalışmamızda enzimlerin yapısı ve karakteristik özellikleri hakkında geniş bilgiler verilmiş olup, kağıt hamurunda meydana getirdiği değişikler değerlendirilmeye çalışılmıştır. Ayrıca ağartmada kullanılan enzim tiplerine değinilmiş ve enzimatik aktiviteyi etkileyen faktörler üzerinde durulmuştur.
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    ENZYMATIC DIGESTIBILITY OF TOMATO, PEPPER, AND EGGPLANT STALKS MIXTURE
    (North Carolina State Univ Dept Wood & Paper Sci, 2012) Çöpür, Yalçın; Özyürek, Ömer; Tozluoğlu, Ayhan; Kütük, Selva
    Turkey annually produces 26 million tons of vegetables and is the third-biggest vegetable producer. After harvest, the waste of vegetable stalks lacking of economic value is burnt or left in the fields, causing environmental pollution. The aim of this study was to examine bioethanol production of a mixture of tomato, pepper, and eggplant stalks using an alternative chemical, sodium borohydrate (NaBH4) in a chemical pretreatment step. Both steam-exploded (SE) and dry-milled (DM) stalks were chemically pretreated and enzymatically hydrolyzed in this study. Results showed that SE stalks had better enzymatic digestibility compared to DM. NaOH treatment removed the highest amount of lignin (17.1%; SE, 2%, 90 min) but also glucose (21.5%; SE, 2%, 90 min) from the structure. On the other hand, NaBH4 removed the highest lignin in proportion to glucose for both SE and DM samples. Enzymatically hydrolyzed stalks gave the highest sugar yields of 30.1% (o.d.-dry matter) for the SE sample when it was pretreated with 2% NaOH for 30 min.