Aysel Kantürk Figen

Yildiz Technical University · Department of Chemical Engineering

The current study aimed to determine the characteristics and kinetic parameters for the pyrolysis of printed circuit board (PCB) wastes including the analysis of evolved gases during the processes at different particle sizes. First, PCB wastes were examined using SEM–EDS, SEM-Mapping and FTIR to gain a better understanding of their structures. Then...

Hydrogen became an energy and energy carrier to ensure universal access to affordable, reliable, and modern energy services within the 2030 Sustainable Development Goals targets. It must consider the environmental effects of new generation technologies that increase energy efficiency and provide clean energy. To provide more efficient energy and sa...

Green hydrogen production coupled with solar energy became a universal concept to provide more efficient energy caring for the environment within the 2030 sustainable development goals target. The green energy concept provides energy systems without negative impact on the environment, economy, and society. At this point, hydrogen became a suitable...

Upcycling of electronic waste is the efficient strategy to minimize the negative effect on environment. In the present study, e-waste (originating from small household appliances) was upcycled into the metal contented pyrolytic carbon (C-WPCB) through a simple pyrolysis without activation or any other additional processes. After crushing and fracti...

Nanoparticles (NPs) thanks to their unique features such as large surface area, high catalytic activity and intra-cellular electron transfer ability used as an enhancement additive in biohydrogen production. Up to date, inorganic, organic and their mixtures of various NPs were produced from different input sources and synthesis methodology. The NPs...

Ammonia borane (NH3BH3) is a reducing agent, able to trap and convert carbon dioxide. In the present work, we used a reactive solid consisting of a mixture of 90 wt.% of NH3BH3 and 10 wt.% of palladium chloride, because the mixture reacts in a fast and exothermic way while releasing H2 and generating catalytic Pd0. We took advantage of such reactiv...

Increasing the biohydrogen production efficiency through the dark fermentation process has become the biggest challenge in recent years. We aim to enhance biohydrogen production yield by adding nano-sized iron oxide doped metal oxides prepared by the wet impregnation method. Biohydrogen production in the presence of additives was evaluated by the s...

In the present study, the semi-continuous regime is evaluated for generating hydrogen (H2) from carbon derivatives of ammonia borane (AB) via hydrolysis in presence of cobalt-doped activated carbon catalyst (Co-AC). Methylamine borane (MeAB) and ethane 1,2 diamine borane (EDAB) is used as an H2 storage medium. At first, catalytic activity tests are...

Aiming at easily recoverable and regenerated catalyst development for efficient hydrogen production from alkyl-substituted amine boranes, boron (B)-doped cobalt (Co) nanoparticles with similar composition and particle size were anchored on two different activated carbon supports: granule and pellet. The effect of different independent variables suc...

One of the levers to mitigate the amount of carbon dioxide (CO2) released into the atmosphere is to capture and use it as cheap, abundant, and safe carbon source, that is, as feedstock in order to produce valuable chemicals like formic acid (HCOOH) that is known to have the potential for high environmental impact reduction. It is in this context th...

In this study, designing of a stable electrospun blended chitosan (CS)-poly(vinyl alcohol) (PVA) nanofibers for colorimetric glucose biosensing in an aqueous medium was investigated. After blending chitosan (CS) and poly(vinyl alcohol (PVA) solutions to get optimum content (CS/PVA:1/4), electrospinnig procedure performed after optimization process...

This study aims to present the hydro-catalytic treatment of organoamine boranes for efficient thermal dehydrogenation for hydrogen production. Organoamine boranes, methylamine borane (MeAB), and ethane 1,2 diamine borane (EDAB), known as ammonia borane (AB) carbon derivatives, are synthesized to be used as a solid-state hydrogen storage medium. The...

The preparation of bead type catalysts, which had a rapid and easy recoverable property for reusability and regeneration procedures during ammonia borane (NH3BH3) hydrolysis, was the main scope of this study. In the present study, the nano-casting procedure was adapted to cobalt oxide (Co3O4) microbeads preparation by multi-step ions exchange proce...

Boron-based rods are ideal for remedial treatments in wood attacked by decay fungi, insects and termites as well as for preventive treatments of high-risk areas in structural timbers and logs internally. This study evaluated the solubility, some physical and thermal properties of the boron-based rods manufactured from either raw ulexite mineral, ra...

With the objective of continuous H2 production from sodium borohydride (NaBH4), methanolytic dehydrogenation has been studied and semi-continuous regimes were evaluated for making H2 production continuous. Batch catalytic hydrogen generation profiles, with kinetic evaluation at different temperatures, were examined. The batch production experiments...

Methanolysis of sodium borohydride (NaBH4) is one of the methods efficient enough to release, on demand, the hydrogen stored in the hydride as well as in 4 equiv of methanol (CH3OH). It is generally reported that, in methanolysis, sodium tetramethoxyborate (NaB(OCH3)4) forms as single component of the spent fuel. It is, however, necessary to clearl...

In this study, reusable hybrid foam catalyst was synthesized, based on reduction of cobalt and ruthenium ions into polyvinyl alcohol (Co–Ru/PVA), for hydrolysis of ammonia borane (NH3BH3, AB) and its derivative methylamine borane, (CH3NH2BH3, MeAB), to generate hydrogen. Sixteen different hybrid catalysts were synthesized under different preparatio...

Electrospinning is a useful and efficient method for fabrication of nano‐sized fibers with high ratio of surface area to volume for broad spectrum of technological areas such as tissue repairing and wood dressing, biosensors, membrane applications, drug delivery, catalytic system and enzyme immobilization. Continuous nanofibers are produced by appl...

In the present study, hydrothermal method (120 °C temperature, 24 h) for synthesis of ultra-layered sheet Cu-Co nanoparticles with various compositions (Cu/(Cu + Co) = 0.1, 0.3, 0.5, 0.7, 0.9) to degrade methyl orange (MO, C14H14N3SO3) organic dye via a catalytic sodium borohydride (NaBH4) reduction is carried out. The Box-Behnken design-response s...

The sustainable ammonia (NH3) synthesis is not only one of the most attractive processes but also one of the most challenging catalytic ones under ambient conditions. The exothermic characteristic of synthesis reaction and also stability and inert behaviour of atmospheric nitrogen (N2) make the conversion of N2 to NH3 hard, while N2 is available in...

This study evaluated boron diffusion from raw boron minerals ulexite and colemanite with low water solubility in comparison to disodium octaborate tetrahydrate (DOT). Tests were conducted using sugi (Cryptomeria japonica (L.) f. D. Don) sapwood and heartwood blocks conditioned to 30, 60, and 90% target moisture content. The blocks were filled with...

This study evaluated boron diffusion from rods made of raw boron minerals, ulexite and colemanite with low water solubility, in comparison with di-sodium octaborate tetrahydrate (DOT). Scots pine (Pinus sylvestris L.) sapwood and heartwood blocks were conditioned to target moisture contents of 30%, 60%, and 90%. The rods were inserted into the bloc...

Electrospun nanofibers are prepared through electrospinning followed by post-treatment and preferred to use in catalytic applications. The electrospinning provides advantages for active catalysts design based on activity profiles and features of catalyst. In the present study, we fabricated nano-crystalline cobalt oxide (Co 3 O 4 ) catalyst by elec...

Ru-Co nanoparticles prepared in nano-size by combustion derived of citric acid used sol-gel technique followed by calcination process at 450 °C. The external and internal properties of nano-sized catalyst were characterized by XRD, XPS, SEM, TEM, ICP-OES, and N2 sorption techniques. The characterization results proved that nano-sized catalyst was m...

Electrospun Ni and Cu metal oxide catalysts are successfully synthesized through electrospinning and conventional sol-gel methods to show advantages of electrospinning on catalytic performance in ammonia borane (NH 3 BH 3 ) methanolysis for hydrogen production. An experimental assessment is presented by the characterization of interior and exterior...

In this study, Langmuir–Hinshelwood and Michaelis–Menten kinetic models are applied to describe the kinetic behaviour of the Co–B catalyst in the hydrolysis of 0.12 M aqueous solutions of boron hydrides at temperatures from 22 to 60°C. Boron hydrides are selected as sodium borohydride (NaBH4, 10 wt % NaOH) and ammonia borane (NH3BH3). Based on the...

Ultrasound-assisted research on both synthesis and in-situ hydrolysis of ammonia borane (NH3BH3) for hydrogen energy application was experimentally investigated in this study. The salt metathesis reaction between sodium borohydride (NaBH4) and ammonia sulfate ((NH4)2SO4) in the presence of organic solvent, tetrahydrofuran (THF), was performed to NH...

The perspective of this study describes a new concept for ammonia borane (NH3BH3, AB) in the form of pellet composited with Co–B catalyst to use as a hydrogen storage medium. For the purpose of this, hydrogen storage capacity and physical-chemical properties of composite pellet are examined and tested to investigate effects of specified environment...

The development of highly efficient catalysts for hydrogen evolution has a crucial significance due to adaptation for sustainable clean energy systems. This study provides potentially powerful approach for catalytic hydrogen evolution based on ammonia borane (NH3BH3) hydrolysis in presence of ternary metal nanoparticles (TMNPs). Herein, we draw up...

Synergetic effect of sodium borohydride (NaBH4) addition to ammonia borane (NH3BH3) hydrolysis reaction had been studied and iron-borate (FeB) was used to catalyze the reaction. Hydrogen generation performance of the hydrolysis reactions was compared for three different operating conditions: (1) in the presence of NaBH4 with FeB catalyst, (2) with...

The use of raw boron minerals (i.e. tincalconite, colemanite, and ulexite) was evaluated to increase the fire performance of wood plastic composites (WPCs) in comparison with commercially available fire retardants (FRs). Cone calorimetry and limited oxygen index tests were performed to evaluate the fire properties of WPC specimens. Artificial weath...

A new hybrid of nanoparticles designed to enable efficient catalysis for hydrogen generation (NPs) include a dual combination of Co, Ni, and Cu transition metals. These nanoparticles are made by altering metals and molar ratios (x: 0.25, 0.50, and 0.75) and synthesized for hydrogen generation by hydrolytic dehydrogenation of ammonia borane (NH3BH3)...

The objective of this study was to investigate the full in-vitro analyses of new-generation bulk-fill dental composites cured by halogen light (HLG). Two types' four composites were studied: Surefill SDR (SDR) and Xtra Base (XB) as bulk-fill flowable materials; QuixFill (QF) and XtraFill (XF) as packable bulk-fill materials. Samples were prepared f...

Amonyum Boran Pelletlerinin Farklı Koşullar Altında Depolanmasının İncelenmesi: Fiziksel, Stabilite ve Performans Testleri

Green bean (Phaseolus Vulgaris L), classified under legume family, is a primary source of dietary protein in human diets especially in the agricultural countries. Green bean is susceptible to rapid deterioration because of their high moisture content and in order to prevent and present the green bean drying process is applied. In this study, effect...

In the present study, thermolysis characteristics and kinetics of ammonia borane–boron composites for hydrogen production were reported. Composites were prepared by ball milling neat ammonia borane with varying weight ratios of 20, 50, and 80 wt% of boron derivatives, namely boric acid and boron trioxide. Differential scanning calorimetry system wa...

The objectives of the study were to investigate the devolatilization kinetics of olive leaves and their utilization as precursors for activated carbon. The devolatilization process was performed using thermogravimetric analysis under nitrogen at heating rates of 10, 15, and 20 °C min⁻¹ with kinetic evaluation by the Coats-Redfern and Horowitz-Metzg...

Investigation of Hydrogen Production in Presence of Nickel Ions From Magnesium Waste

In the present study, Electrospun nanofibers (Co-NF, Ni-NF, and Cu-NF) were used as efficient catalysts for hydrogen release through ammonia borane (NH3BH3) hydrolysis. Poly(vinyl alcohol) solutions containing metal acetates provided sol–gel materials for electrospinning. The electrospun fibers were fabricated by a low cost and facile technique. Th...

Calcium hydride (CaH2) reacts vigorously with water, liberating hydrogen gas. For the development of an effective hydrogen storage system, it is an absolute necessity to control the rate of hydrogen production. In the present study, the effects of different solvent, ethylene glycol, methanol, and ethanol, on the hydrolysis of CaH2 for controllable...

The present study reports experimental results the effectivity of hydrogen production by the hydrolysis of milled waste magnesium scraps (MWMS) in nickel chloride (NiCl2) solutions (0.5 M–2.5 M) and NiCl2 added in Marmara Sea and Aegean Sea water. A micro-batch reactor is considered as hydrogen evolution reaction in solutions with variety of conduc...

Novel mucoadhesive montmorillonite/starch-graft-poly (methacrylic acid) nanocomposite hydrogels (Mt/S-g-PMAA) based on gelatinized wheat starch, an anionic monomer methacrylic acid (MAA), and different amounts of montmorillonite (Mt) as nanoparticles were synthesized according to the conventional grafting reaction mechanism in the aqueous media. Th...

The use of wood polymer composites (WPC) is rapidly increasing all around the world. WPC is produced by mixing wood flour -especially obtained from wastes of wood products industry - with polymers such as low density (LDPE), high density polyethylene (HDPE), polyprophylene (PP), etc. The major advantages of WPC are high resistance to water absorban...

Effects of open-air sun drying and pre-treatment on drying characteristic of purslanes (Portulaca oleracea L.) were investigated. Drying times were determined as 31, 24 and 9 h for natural, salted and blanched, respectively. The higher “L” value and lower “−a/b” ratio values were obtained in natural dried purslane. The Aghbashlo et al. model gave a...

In the present study, waste Mg based material (W/Mg) was used as a raw material for the generation of hydrogen. Ball milling and saline solution method were performed to ensure full completion of the hydrolysis reaction. Improved texture properties were obtained by ball milling W/Mg for 15 h (2.29 m2 g−1 BET area, 11.94 μm particle size). Ball mill...

The use of boric acid (H3BO3) and boron oxide (B2O3) for the synthesis of cobalt-based catalysts by the co-precipitation technique was investigated and catalytic activities in hydrogen generation were evaluated. Different cobalt salts [cobalt (II) chloride (CoCl2 · 6H2O), cobalt sulfate (CoSO4 · 5H2O) and cobalt(II) nitrate (Co(NO3)2 · 7H2O)] were...

Abstract The aim of this study was to evaluate the thermal, spectral, and surface properties of four different bulk fill materials - SureFil SDR (SDR, Dentsplay DETREY), QuixFil (QF, Dentsplay DETREY), X-tra base (XB, Voco) X-tra fil (XF, Voco) - polymerized by light-emitting diode (LED). Resin matrix, filler type, size and amount, and photoinitiat...

In this study, the thermal behavior in terms of glass transition (T g), degradation, and thermal stability of four commercial new-generation posterior bulk fill composites (Surefill SDR, Dentsply; Quixfill, Dentsply; Xtrabase, Voco; and Xtrafill, Voco) activated by light-emitting diodes (LEDs) was analyzed by thermogravimetric analysis (TG), differ...

In the present study, hydrogen desorption properties of magnesium hydride (MgH2) synthesized from modified waste magnesium chips (WMC) were investigated. MgH2 was synthesized by hydrogenation of modified waste magnesium at 320 degrees C for 90 min under a pressure of 6 x 10(6) Pa. The modified waste magnesium was prepared by mixing waste magnesium...

Co-B catalysts are promising candidates for hydrogen evolution via hydrolysis of alkaline sodium borohydride (NaBH4) solutions. In the present paper, a sonochemical approach was investigated for synthesis of Co-B catalysts and hydrolysis of alkaline NaBH4 solutions. Sonochemical application on synthesizing process improved the intrinsic and extrins...

Manufacturing panels from Tetra Pak (R) (TP) packaging material might be an alternative to conventional wood-based panels. This study evaluated some chemical and physical properties as well as biological, weathering, and fire performance of panels with and without zinc borate (ZnB) by using shredded TP packaging cartons. Such packaging material, a...

In this study, the synthesis of barium metaborate powder (BaB2O4) was carried out by ultrasound-assisted precipitation using different borate solutions. Different solutions such as borax (Na2B4O7, BD), boric acid (H3BO3, BA), and sodium metaborate (NaBO2, SMB) were used in the synthesis and an ultrasonic immersion horn probe was used as the major s...

In this study, the characterization and modification of waste magnesium chips (WMCs), which were produced by plastic molding in a gold manufacturing factory and are used as Mg-rich intermetallic composites in storing hydrogen, were discussed in detail. WMCs were analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF) spectroscopy, differen...

In this study, barium metaborate (BaB2O4, BMB) synthesis from the borax solution was carried out. BMB currently is used in production of ceramic glazes, luminophors, oxide cathodes as well as additives to pigments for aqueous emulsion paints and also beta-BaB2O4 single crystals are the best candidate for fabrication of solid-state UV lasers operati...

In the present study, synthesis, structural characterization, and hydrolysis of the promising hydrogen storage carrier ammonia borane (NH3BH3), were investigated. NH3BH3 was prepared by one-pot chemical reaction between sodium borohydride (NaBH4) and different ammonia salts [NH4X, X: SO4, CO3, Cl] in the presence of solvent, tetrahydrofurane (THF)....

Düşük Ağırlıklı Kompleks Hidrürlerin Hidrolizi İçin CoB Katalizörlerinin Sentezlenmesi ve Karakterizasyonu

In this study, the solid state synthesis and reaction kinetics for Co/B as a catalytic/acidic accelerator for sodium borohydride (NaBH4) hydrolysis were investigated. The Co/B a catalytic/acidic accelerator was synthesized from cobalt(II) chloride hexahydride (CoCI2·6H2O) and boron oxide (B2O3) by a procedure based on solid state synthesis. Differe...

In the present study, dehydrogenation characteristics of ammonia borane (NH3BH3) catalyzed via boron-based catalysts under different hydrolysis conditions were investigated. A series of boron-based catalysts (Co1-x-B-x, Ni1-x-B-x, and Cu1-x-B-x, x: 0.25, 0.50, 0.75) were prepared by so gel method. Gels were calcinated at different temperatures (250...

The thermal behavior of tunellite has been examined by using thermal analysis data at different heating rates. Coats–Redfern, Horowitz–Metzger, Piloyan–Novikova, Doyle, and isoconversional Ozawa kinetic models have been used for the non-isothermal dehydration kinetic investigation of the mineral. The kinetic parameters are computed using the above-...

hermal degradation characteristics of Tetra Pak panel boards (TPPB) can be useful to improve usage of such panels as an alternative to wood-based products such as plywood, fiberboard, and particleboard. In the study, samples from the TPBBs manufactured from waste Tetra Pak packages (WTPP) were heated in a nitrogen atmosphere at different heating ra...

In the present study, a novel microwave assisted method has been developed for sodium metaborate dihydrate (NaBO2·2H2O) synthesis. Anhydrous NaBO2, a derivative of borax, is an industrially and technologically important boron compound used as a raw material for the thermochemical production of sodium borohydride (NaBH4). The effects of different mi...

In this study, a novel perspective has been proposed as “Ultrasonic Hydrolysis” for hydrogen generation from ammonia borane (NH3BH3) with cobalt–boron (Co–B) catalysts. The Co–B catalysts are prepared by the sol–gel reaction of boron oxide (B2O3) with cobalt(II) chloride hexahydrate (CoCI2.6H2O) in the presence of citric acid (C6H8O7). Two types of...

The presence of caustic soda in the spent sodium borohydride (NaBH4) fuel in high concentrations creates environmental problems associated with the transportation and the disposal of the fuel, orits recycling into NaBH4. It is clear that the high level of caustic soda in the spent fuel requires efficient and proper formulation of its industrial rec...

The Co-B catalysts were known optimal catalyst as not only with its activeness for hydrolysis reaction of sodium borohydride (NaBH4) but also its economic cost. In literature Co-B catalyst were prepared by chemical reduction by using NaBH4 as a hydrogen source and also for supports prepared by sol-gel and impregnation [1-7]. NaBH4 as one of the l...

Energy requirement of the World is increasing day by day cause of the active proses like improvement of technology and rising of population. What is more in consequence of effect of global warming, depletion of fossil fules, the hydrogen has become one of the most popular enegry resources sources. Hydrogen generation from the hydrolysis reaction of...

The mechanism for the formation of sodium borohydride (NaBH $_{\boldsymbol{4}})$ was investigated for its ability to store hydrogen in the borosilicate glass–sodium (BSG–Na) solid system under low hydrogen pressure. BSG, which was prepared by melting borax with silica, was used as the starting material in the BSG–Na system that would be prepared t...

Devolatilization behavior of several types of agricultural stalks (sunflower, rice, corn, and wheat) was studied using thermogravimetric system (TG) under nitrogen atmosphere at different heating rates (10, 15, and 20 °C min-1). Coats&Redfern, Horowitz&Metzger, and Arrhenius non-isothermal kinetic models were applied to calculate the devolatilizati...

In this study, the solid-state reaction mechanism and kinetics were investigated for production of anhydrous sodium metaborate (NaBO2), an industrially and technologically important boron compound. To assess the kinetics of solid-state production of NaBO2, the chemical reaction between borax (Na2B4O7) and sodium hydroxide (NaOH) was investigated by...

Sodium metaborate, a derivative of the borax compound, has a wide range of industrial applications. Recently, it is used as a source of boron in the production of sodium borohydride (NaBH4), which is a medium for hydrogen storage. In the present study, sodium metaborate tetrahydrate (SMT, NaB(OH)4·2H2O) was produced by the reaction of borax (B) wit...

Sodium metaborate (NaBO 2), is a compound derivative of borax, is used in the chemical industry as photographic and textile chemicals, detergents, cleansers, and adhesives. Literature on NaBO 2 used as sources of boron in the production of the NaBH 4 methods is available. Therefore, the use of anhydrous NaBO 2 in the energy field and the importance...

In this study, anhydrous sodium metaborate (NaBO2), an industrial and technologically important boron compound, synthesis from concentrated tincal (CT) was carried out. Experiments with different temperature and time were performed in the parametric investigation to map out the reaction mechanism. Crystalline phase characterization of metaborates p...

Coats-Redfern, Arrhenius, Ozawa, Kissinger, and Doyle non-isothermal kinetic models were used to calculate the dynamic kinetic parameters for dehydration reaction of Mg-borate mineral, inderite (Kırka — Turkey) based on thermogravimetric analysis, derivative thermogravimetric analysis and differential thermal analysis. Dehydration experiments were...

Sodium metaborate tetrahydrate (NaB(OH)4·2H2O) was synthesized by reaction of anhydrous borax (Na2O·2B2O3) with sodium hydroxide (NaOH) under conditions at 90 °C for 150 min. The structure was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) and Thermogravimetric (TG) anal...

Global energy and ecology problems continue to grow because of burning of fossil fuels,environmental pollution, decrease of energy sources and difficulties in storing electricity.Hydrogen has great potential to solve these problems as an environmentally clean energycarrier and as a way to reduce reliance on imported energy sources. Hydrogen can be...

This paper presents a new process for producing sodium borohydride (NaBH4), which can be used as a hydrogen storage medium. The process is based on the conversion reaction of borosilicate glass at temperatures between about 400 and 500∘C under high hydrogen pressure of 22atm. For this purpose, borax (Na2B4O7) is sintered with quartz powder (SiO2) t...