Ayhan Tozluoğlu

Incorporation of hazelnut shell and husk in MDF production

Hazelnut shell and husk (Coryllus arellana L.) is an abundant agricultural residue in Turkey and investigating the possibilities of utilizing husk and shell in panel production might help to overcome the raw material shortage that the panel industry is facing. The aim of this work was to investigate the possibilities of utilizing hazelnut shell and husk in medium density fiberboard (MDF) production. To produce general purpose fiberboards, fiber-husk and fiber-shell mixtures at various percentages were examined in this study. The results indicated that panels could be produced utilizing hazelnut husk up to 20% addition without falling below the properties required in the standards. Shell addition was restricted up to 10%, because higher addition levels diminished the elastic modulus and internal bond strength below the acceptable level.

Evaluating pretreatment techniques for converting hazelnut husks to bioethanol

This study examined the suitability of husk waste for bioethanol production and compared pretreatment techniques with regard to their efficiencies. Results showed that 4% NaBH4 (90 min) delignified the highest amount of lignin (49.1%) from the structure. The highest xylan solubility (77.9%) was observed when samples were treated with 4% NaOH for 90 min. Pretreatment with NaOH and NaBH4, compared to H2O2 and H2SO4, resulted in selective delignification. The highest glucan to glucose conversion (74.4%) and the highest ethanol yield (52.6 g/kg husks) were observed for samples treated with 2% NaOH for 90 min.

Sodium borohydrate (NaBH4) pretreatment for efficient enzymatic saccharification of wheat straw.

In this study, the aim was to examine bioethanol production of wheat straw residues using an alternative chemical, sodium borohydrate (NaBH(4)) in chemical pretreatment step. The obtained results showed that sodium hydroxide (NaOH) and NaBH(4) treated straw resulted in 87.8% and 83.3% glucan conversion in enzymatic hydrolysis, but hydrogen peroxide (H(2)O(2)) (74.7%) and sulfuric acid (H(2)SO(4)) (71.7%) had lower glucan conversion. The highest ethanol yield from untreated straw (115 g/kg) was observed for 4% NaBH(4) pretreated sample (60 min) and the theoretical yield (86.9%) was also calculated to be highest for the sample.

Influence of PVA and silica on chemical, thermo-mechanical and electrical properties of Celluclast-treated nanofibrillated cellulose composites

This study reports on the effects of organic polyvinyl alcohol (PVA) and inorganic silica polymer on properties of Celluclast-treated nanofibrillated cellulose composites. Nanofibrillated cellulose was isolated from Eucalyptus camaldulensis and prior to high-pressure homogenizing was pretreated with Celluclast enzyme in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose (CNF), nanocellulose-PVA (CNF-P) and nanocellulose-silica (CNF-Si). Chemical characterization, crystallization and thermal stability were determined using FT-IR and TGA. Morphological alterations were monitored with SEM. The Youngs and storage moduli of the nanocomposites were determined via a universal testing machine and DTMA. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. The crystallinity values of the nanocomposites calculated from the FT-IR were in agreement with the TGA results, showing that the lowest crystallinity value was in the CNF-Si. The CNF-P displayed the highest tensile strength. At a high temperature interval, the storage modulus of the CNF-Si was greater than that of the CNF or CNF-P. The CNF-Si also exhibited a completed singular relaxation process, while the CNF and the CNF-P processes were uncompleted. Consequently, in terms of industrial applications, although the CNF-P composite had mechanical advantages, the CNF-Si composite displayed the best thermo-mechanical properties.

Matrix impact on the mechanical, thermal and electrical properties of microfluidized nanofibrillated cellulose composites

Abstract This study reports on the effect of organic polyvinyl alcohol (PVA) and silica matrix on the properties of cellulose-based nanocomposites. Nanofibrillated cellulose was isolated from kraft pulp and treated with Pulpzyme HC 2500 enzyme prior to high-pressure homogenization in order to lower energy consumption. Three nanocomposite films were fabricated via the casting process: nanofibrillated cellulose, nanocellulose-PVA (NC-PVA) and nanocellulose-silica (NC-Si). Chemical characterization and crystallization were determined with FTIR. Thermal stability was investigated with thermogravimetric analysis. Morphological alterations were monitored with scanning electron microscopy. A universal testing machine and dynamic mechanical thermal analysis were used for determination of Young’s and storage moduli. The real and imaginary parts of permittivity and electric modulus were evaluated using an impedance analyzer. Considerable alterations were seen under FTIR. Thermal stability was lower in NC-Si than in NC-PVA due to lower crystallinity. Higher Young’s modulus and storage moduli were observed in NC-PVA than in NC-Si. NC-PVA exhibited a singular relaxation process, while a double relaxation process was seen in NC-Si. Consequently, the nanocomposite film prepared from the organic matrix (NC-PVA) had a mechanical advantage for industrial applications. However, neat NC composite revealed the highest storage modulus and thermal stability.

NaBH4 Pretreatment in Bioethanol Production of Corn Stalks

Abstract Corn stalks, which are an abundant agricultural waste product in Turkey, have a high carbohydrate structural content and could be a valuable raw material for bioethanol production. In this study, stalks with crystalline cellulose and complex lignin and hemicellulose distribution in their structure were first steam-exploded and then chemically treated to achieve efficient hydrolysis. The conventional chemicals sodium hydroxide (NaOH), sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and an alternative chemical, sodium borohydrate (NaBH4), were utilized in the chemical treatment procedure. Results showed that the samples treated with NaOH (83.9%) and NaBH4 (82.9%) gave higher glucan conversion in enzymatic hydrolysis compared to those treated with H2O2 (74.5%) and H2SO4 (56.6%). The highest ethanol yield from untreated stalks (97.4 g/kg) was obtained when the stalks were pretreated with 4% NaBH4 for 90 min; the theoretical ethanol yield was found to be 72.5%.

The effects of boron derivatives as pretreatment chemicals for biodegradation of sunflower stalks

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)3H2O], boron oxide [B2O3], borax decahydrate [Na2B4O710H2O], disodium octaborate tetrahydrate [Na2B8O134H2O] 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%).

Effects of cellulose micro/nanofibers as paper additives in kraft and kraft-NaBH4 pulps

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-1piperidinyloxy (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 kraftNaBH4 pulp displayed increases of 8.32-18.3% and 2.338.86% in tensile strength and 6.00-14.0% and 14.0-22.0% in oSR, 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. ADDRESSES OF THE AUTHORS: Ayhan Tozluoglu (ayhantozluoglu@duzce.edu.tr) Forest Product Engineering, Faculty of Forestry, Duzce University, 81620 Duzce, Turkey Bayram Poyraz (bayrampoyraz@duzce.edu.tr) Polymer Engineering Department, Faculty of Technology, Duzce University, 81620 Duzce, Turkey Corresponding author: Ayhan Tozluoglu