Browsing by Author "Depci, Tolga"

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Adsorption of Crystal Violet From Aqueous Solution on Activated Carbon Derived From Golbasi Lignite
(oficyna Wydawnicza Politechniki Wroclawskiej, 2012) Depci, Tolga; Kul, Ali Riza; Onal, Yunus; Disli, Erkan; Alkan, Salih; Turkmenoglu, Z. Funda
Activated carbon (AC) was obtained from lignite of the local resource, Golbasi - Adiyaman (Turkey) by chemical activation. The Golbasi lignite was chosen as the precursor for its availability and low cost. The BET surface area of the activated carbon was found 921 m2/g. The AC was used as an adsorbent for Crystal Violet (CV) in aqueous solution. The adsorption properties of CV onto the activated carbon are discussed in terms of the adsorption isotherms (Langmuir and Freundlich) and the kinetic models (pseudo-first-order, pseudo-second-order and intraparticle diffusion model). It was shown that the experimental results best fitted by the Langmuir model, and the second-order kinetic equation. The thermodynamic parameters show that the adsorption process is endothermic. The experimental results point out that the obtained activated carbon is a viable candidate for sorbent removing CV from aqueous solutions.
Adsorption of Crystal Violet on Activated Carbon Prepared From Coal Flotation Concentrate
(Iop Publishing Ltd, 2016) Aydogmus, Ramazan; Depci, Tolga; Sarikaya, Musa; Kul, Ali Riza; Onal, Yunus
The objective of this study is firstly to investigate the floatability properties of Zilan-Van coal after microwave irradiation and secondly to produce activated carbon from flotation concentrate in order to remove Crystal Violet (CV) from waste water. The flotation experiments showed that microwave heating at 0.9 kW power level for 60 sec exposure time enhanced the hydrophobicity and increased the flotation yield. The activated carbon with remarkable surface area (696 m(2)/g) was produced from the flotation concentrate and used to adsorb CV from aqueous solution in a batch reactor at different temperature. The adsorption properties of CV onto the activated carbon are discussed in terms of the adsorption isotherms (Langmuir and Freundlich) and found that the experimental results best fitted by the Langmuir model.
Characteristic Properties of Adsorbed Catalase Onto Activated Carbon Based Adiyaman Lignite
(Parlar Scientific Publications (p S P), 2011) Depci, Tolga; Alkan, Salih; Kul, Ali Riza; Onal, Yunus; Alacabey, Ihsan; Disli, Erkan
Catalase is one of the most common and important enzymes in biological systems. However, its purification process has some difficulties and it can be easily decomposed in aqueous or nonaqueous solutions. Therefore, a catalase should be adsorbed on solid materials to reduce its inactivation and to increase its economic value. Activated carbon which was obtained from Turkish low-rank coal (Golbasi-Adiyaman) by chemical activation was used as a solid carrier to adsorb catalase for the first time in this research. The pore structure of the activated carbon was determined by A Tri Star 3000 (Micromeritics, USA) surface analyzer and scanning electron microscope. In order to determine adsorption properties of catalase, ionic strength effect, temperature-activity, pH-activity, storage stability and operational stability of the activated carbon were investigated. The kinetic and thermodynamic mechanisms of adsorbed enzyme were also studied. The experimental results pointed out that the obtained activated carbon is a viable candidate for an alternative solid carrier for catalase and it may be a promising material for various biotechnological applications.
Chemical Characterization of Patnos Scoria (Agri, Turkey) and Its Usability for Production of Blended Cement
(oficyna Wydawnicza Politechniki Wroclawskiej, 2012) Depci, Tolga; Efe, Tugba; Tapan, Mucip; Ozvan, Ali; Aclan, Mustafa; Uner, Tijen
This paper reports results of investigations on suitability of scoria (PTS), collected from Patnos (Agri) in Turkey, for blended cement production. Scoria (basic pumice) was chosen as cement replacement materials due to its availability and cost in Agri in Turkey. The portland cement was replaced by scoria within the range of 0, 5, 10, 20, 30, 40 and 50%. Characterization of scoria was subjected by the X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), BET surface area and porosity, zeta potential (zeta) and thin sections. The standard tests were conducted for the obtained fresh and hardened states of scoria blended cement paste. Furthermore, the obtained cements were characterized by the XRF. According to experimental results, scoria up to 20% ratio could be added into clinker and it has a good potential of manufacturing blended scoria cement.
Comparison of Activated Carbon and Iron Impregnated Activated Carbon Derived From Golbasi Lignite To Remove Cyanide From Water
(Elsevier Science Sa, 2012) Depci, Tolga
The ability of lignite-activated carbon (LAC) and iron-impregnated activated carbon (FeAC) obtained from Golbasi lignite to remove cyanide ions from aqueous solution by adsorption was researched and compared with each other. The same process was applied also with commercial activated carbons which are in both granular (CAC-1) and powder forms (CAC-2). The morphologies, structures and properties of the activated carbons were determined by BET, XRD, XRF, SEM, zeta meter and magnetometer, respectively. The effects of various experimental parameters, such as initial cyanide concentration, pH, adsorbent type and particle size were researched in a batch adsorption technique at a temperature of 25 degrees C. BET surface area of LAC is determined as 921 m(2)/g. The obtained magnetic activated carbon has high surface area of 667 m(2)/g with 19 wt.% Fe3O4 coated and perfect magnetic separation performance. Langmuir model was found to be the best representative for cyanide-adsorption. The maximum monolayer adsorption capacities of LAC and FeAC are 60.18 mg/g and 67.82 mg/g at pH values of 7-7.5 and 64.10 mg/g and 68.02 mg/g at pH values of 10-10.5, respectively. Kinetic evaluation indicated that the cyanide adsorption onto the obtained activated carbons followed the pseudo-second order rate reaction. The diffusion-controlled kinetic models on the cyanide-adsorbent system showed that the removal rate was controlled not only by intraparticle diffusion but also by film diffusion. All experimental results point out that the LAC and FeAC are viable candidates for the removal of cyanide from water and wastewater. (C) 2011 Elsevier B.V. All rights reserved.
Comparison of Different Synthesis Methods To Produce Lithium Triborate and Their Effects on Its Thermoluminescent Property
(Springer, 2010) Depci, Tolga; Ozbayoglu, Gulhan; Yilmaz, Aysen
Lithium triborate (LiB3O5) was produced by different synthesis methods, which included high-temperature solid-state reaction, microwave-assisted high-temperature solid-state reaction, and precipitation-assisted high-temperature solid-state reaction. After the synthesis, metal oxides (CuO and Al2O3) were doped into LiB3O5 to enhance its thermoluminescent (TL) properties, and the TL intensities were compared with each other. The identification and characteristics of undoped and doped LiB3O5 were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) analyses, differential thermal analyses (DTA), scanning electron microscopy (SEM), and particle size analyzer. The glow curves were obtained by using a TL reader. The results showed that synthesis routes affected the physical and structural properties of lithium triborate, which have an important effect on its TL intensity.
Competitive Adsorption of Lead and Zinc From Aqueous Solution on Activated Carbon Prepared From Van Apple Pulp: Study in Single- and Multi-Solute Systems
(Elsevier Science Sa, 2012) Depci, Tolga; Kul, Ali Riza; Onal, Yunus
The potential of activated carbon (VAAC) prepared from local agricultural waste, apple pulp, as an alternative low-cost adsorbent was investigated for the removal of lead and zinc from single- and multi metal aqueous solution. VAAC was produced with a reasonable yield, 43% and has remarkable surface area (1067.01 m(2)/g) with a well-developed pore structure. To determine the adsorption process and properties, the effects of various operating parameters, pH of the solutions (2-6), adsorbent dosage (0.01-0.2 g), initial concentration of metal ions (25-40 mg/L), contact time (3-120 min) and temperature (298-308 K) were investigated in a batch adsorption technique. The adsorption isotherm data were better fitted by Langmuir model. The pseudo second-order model was found more applicable to describe the kinetic of system in both the single- and multi-solute system. The adsorption capacities of heavy metals decrease in the order of Pb(II) (15.96 mg/g) < Pb (Pb + Zn) (13.23 mg/g) < Zn(II) (11.72 mg/g) < Zn (Pb + Zn) (7.54 mg/g) at 298 K. Although individual metal ions adsorption decreases in multi-system. the more metal ions are adsorbed (20.77 mg/g). The intraparticle diffusion model, external mass transfer coefficient, film and pore diffusion coefficient at different temperatures were also evaluated to investigate the adsorption mechanisms of both systems. The adsorption was mainly controlled film diffusion process at all operating temperatures and concentrations. The thermodynamic parameters indicate that the adsorption process is endothermic, feasible and thermodynamically favored. (C) 2012 Elsevier B.V. All rights reserved.
Effect of Physical, Chemical and Electro-Kinetic Properties of Pumice on Strength Development of Pumice Blended Cements
(Springer, 2013) Tapan, Mucip; Depci, Tolga; Ozvan, Ali; Efe, Tugba; Oyan, Vural
In the present study, the potential effects of physical, chemical and electro-kinetic properties of pumice on the strength development of pumice blended cements (PBC) were examined and documented. A significant relationship between zeta potential of pumice samples, setting time and water demand of PBC was found. A relationship between the chemical content of pumice samples and compressive strength of PBC was also observed. However, zeta potential of the pumice samples was found to be less effective in strength development. Despite the lower clinker content, the setting time of the PBC samples was shorter than control specimen. 30 % pumice replacement by clinker resulted in 5-28 % reduction in 28-day strength depending on the characteristics of the pumice samples and grinding time.
Effect of Physical, Chemical and Electro-Kinetic Properties of Pumice Samples on Radiation Shielding Properties of Pumice Material
(Pergamon-elsevier Science Ltd, 2014) Tapan, Mucip; Yalcin, Zeynel; Icelli, Orhan; Kara, Husnu; Orak, Salim; Ozvan, Ali; Depci, Tolga
Pumice has been used in cement, concrete, brick, and ceramic industries as an additive and aggregate material. In this study, some gamma-ray photon absorption parameters such as the total mass attenuation coefficients, effective atomic number and electronic density have been investigated for six different pumice samples. Numerous values of energy related parameters from low energy (1 key) to high energy (100 MeV) were calculated using WinXCom programme. The relationship between radiation shielding properties of the pumice samples and their physical, chemical and electro-kinetic properties was evaluated using simple regression analysis. Simple regression analysis indicated a strong correlation between photon energy absorption parameters and density and SiO2, Fe2O3, CaO, MgO, TiO2 content of pumice samples in this study. It is found that photon energy absorption parameters are not related to electro-kinetic properties of pumice samples. (C) 2013 Elsevier Ltd. All rights reserved.
Evaluation of Stucco Binder for Agglomeration in the Heap Leaching of Copper Ore
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Depci, Tolga; Dhawan, Nikhil; Wang, Xuming; Lin, C. L.; Miller, Jan D.
It is known that the presence of excess fines in heap leaching operations may cause low recovery due to reduced heap permeability and/or channeling of lixiviant flow. These problems are mitigated to some extent by agglomeration pretreatment prior to heap leaching. Sulfuric acid leach solution is the conventional liquid bridge used for copper ore agglomeration, but these agglomerates exhibit poor stability when compared to the agglomerates formed using stucco binder, calcium sulfate hemihydrates, CaSO(4)center dot 1/2H(2)O. Results obtained from agglomeration experiments on the Zaldivar ore reveal that the stucco hydration reaction provides the agglomerates with more stability, increased size with less release of fines, and better permeability of the packed agglomerate bed. A phase diagram has been constructed to identify preferred agglomeration conditions. Finally a proposed description for the action of stucco binder during the agglomeration process is presented and discussed. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluation of Stucco Binder for Agglomeration in the Heap Leaching of Copper Ore (Vol 24, Pg 886, 2011)
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Depci, Tolga; Dhawan, Nikhil; Wang, Xuming; Lin, C. L.; Miller, Jan D.
Identification of Chrysotile in Local Soil at Beypinari Village (sivas-Turkey) Regarding Mine and Health Issue
(Springer india, 2016) Onal, Yunus; Depci, Tolga; Onal, Ayten; Onal, Ali; Uner, Tijen
Asbestos is dangerous for health and is forbidden to use in Turkey, but villagers who live in rural eastern part still use it especially for their home for insulation purposes and even as a substitute for baby powder. Therefore, geological and chemical properties of this type of soil, which is near the settlement, should be characterized and identified from the point of view of health. Beypinari asbestos deposits are located at Beypinari village, about 90 km southeast of Sivas, Turkey within Central Anatolian Ophiolites. Therefore, in the present study, the existence of chrysotile in Beypinari asbestos deposit were characterized and identified by mineralogical analysis and by major, trace, REE analysis. The results show that the samples contain different amount of calcite mineral, the main mineral being chrysotile.
Investigation of Applicability of Edremit Travertine and Pumices Outcorpping North of Van Lake in Cement Sector
(2011) Efe, Tuğba; Depci, Tolga
Çimento dünyada en çok tüketilen malzemelerden birisi olup, yapı sektörünün temel bileşenidir. Artan nüfus ve yapılaşmaya bağlı olarak çimento ihtiyacı da artmaktadır. Çimento üretimi yoğun enerji gerektiren bir süreçtir. Bu nedenle son yıllarda çimento klinkerine öğütme aşamasında çeşitli katkı malzemeleri eklenmektedir. Böylece hem teknik açıdan daha iyi niteliklerde çimento üretilebilinmekte, hem de enerji tasarrufu sağlanarak ekonomik kazanç sağlanmaktadır. Aynı zamanda ısı enerjisi için gereken yakıt miktarından tasarruf sağlanarak CO2 salınımı azaltılmakta ve çevrenin korunmasına katkıda bulunulmaktadır.Bu tez çalışmasında, Van ili Edremit ilçesinde bulunan Van Aşkale Çimento Fabrikası'na ait ruhsatlı traverten ocağındaki travertenlerin ve Van Gölü kuzeyinde yüzeylenen pomzaların çeşitli oranlarda çimento içerisine katılarak, çimento sektöründe katkı maddesi olarak kullanılabilirliği araştırılmıştır. Bu amaç doğrultusunda pomza katkılı çimentolar ve traverten katkılı çimentolar üretilmiştir. Üretilen çimentoların yoğunluk, çimento inceliği, priz süreleri, su içeriği, hacim genleşmesi, 1, 2, 7 ve 28, günlük ortalama basınç dayanımları deneyleri yapılmıştır. Ayrıca pomza örneklerine puzolanik aktivite deneyi gerçekleştirilmiştir. Üretilen katkılı çimentoların fiziksel ve kimyasal özellikleri portland çimentosuyla karşılaştırılmıştır.Madde karakterizasyonu çalışmaları kapsamında pomza ve travertenlerin fiziksel ve kimyasal özellikleri XRF, XRD, BET, SEM, DTA, TGA, Zeta potansiyeli,Hardgrove öğütülebilirlik indeksleri, gerçek yoğunlukları, ince kesit ve FTIR analizleri yapılarak çimentoda katkı malzemesi olarak kullanılmaya uygunlukları araştırılmıştır. Elde edilen Deneysel veriler ışığında söz konusu pomza ve travertenlerin çimentoda katkı malzemesi olarak kullanılmaya uygun oldukları belirlenmiştir.
Mineralogical and Chemical Characterization of Acidic Pumices Outcrop North of Lake Van
(Iop Publishing Ltd, 2016) Yucel, Aysegul; Efe, Tugba; Onal, Mehmet; Depci, Tolga; Aydin, Harun
In the present study, mineralogical, physical and chemical characteristics of the pumice located in North of Lake Van locations were investigated to find an applicability of them for cement and textile industry. Characterization studies of the pumice samples were carried out by thin section, SEM, XRF, XRD and FTIR analysis. In addition, the bulk density, Hard Grove Index (HGI), pozzolanic activity and reactive silica of the pumice samples were determined. The overall results showed that the pumice samples, which might be an eruption product of Mount Suphan, had an amorphous structure and rhyolite composition in high calcalkaline series. The chemical compositions and physical properties indicated that the pumice samples could be used in cement and textile industry.
A New Statistical Physics Model To Interpret the Binary Adsorption Isotherms of Lead and Zinc on Activated Carbon
(Elsevier Science Bv, 2016) Sellaoui, Lotfi; Depci, Tolga; Kul, Ali Riza; Knani, Salah; Ben Lamine, Abdelmottaleb
New statistical physicochemical interpretations of an adsorption process at molecular level were developed to explain the binary adsorption isotherms of lead and zinc ions on activated carbon derived from Styrax officinalis seeds (Balikesir, Turkey) and a commercial activated carbon at different temperatures, 298, 308 and 318 K. The extended Hill model was developed to explain heterogeneous model in terms of the grand canonical ensemble in statistical physics. Steric and energetic parameters, like the numbers of ions per site n(1) and n(2), the densities of receptor sites N-M1 and N-M2 and the adsorption energies (-epsilon(1)) and (-epsilon(2)) were directly obtained from the fitting of the experimental adsorption isotherms by numerical simulation to describe the process. The simulation results suggested that two adsorbates per site were anchored on activated carbon surface. The magnitudes of the calculated adsorption energies indicated that Zn2+ and Pb2+ were physically adsorbed by the activated carbon. Thermodynamic potential functions, namely entropy, enthalpy and internal energy were calculated to explain the order and disorder of the adsorbate at the adsorbent surface during the binary adsorption process. The values of the free enthalpy and the internal energy indicated spontaneous adsorption process. (C) 2015 Elsevier B.V. All rights reserved.
Particle Damage and Exposure Analysis in Hpgr Crushing of Selected Copper Ores for Column Leaching
(Pergamon-elsevier Science Ltd, 2011) Kodali, Phanindra; Dhawan, Nikhil; Depci, Tolga; Lin, C. L.; Miller, Jan D.
In mining operations, jaw and gyratory crushers are generally used for primary crushing, and cone crushers are used for secondary crushing. During the past decade, however, high-pressure grinding rolls (HPGR) are being considered due to potential processing benefits such as energy savings, improved exposure/liberation and particle weakening. At this time there is no detailed quantification of particle damage and downstream benefits from HPGR crushing are uncertain. In the present research, copper ores (copper oxide ore and copper sulfide ore) were crushed by a jaw crusher and by HPGR and the products were evaluated for particle damage and copper grain exposure by X-ray computed tomography. Column leaching was done to determine the rate and extent of copper recovery. X-ray computed tomography analysis and laboratory column leaching experiments for copper oxide ore revealed that products from HPGR crushing have more particle damage and higher copper recoveries when compared with products of the same size class from jaw crusher crushing. Generally the copper recovery from column leaching of the oxide ore was found to be dependent on the extent of grain exposure, which increases with a decrease in particle size. In the case of the copper sulfide ore, copper recovery was found to be independent of the crushing technique despite the fact that more particle damage was observed in products from HPGR crushing. This unexpected behavior for the copper sulfide ore might be due to the high head grade and strong leach solution. Column leaching results also show that about 80-90% of the copper was recovered from the copper sulfide ore in a relatively short leaching time irrespective of crushing technique. As expected, copper recoveries improved with a decrease in the particle size of the copper sulfide ore as exposure of copper mineral grains increased. (C) 2011 Elsevier Ltd. All rights reserved.
Synthesis and Thermoluminescence Properties of Rare Earth Oxides (Y, Ce-Lu) Doped Lithium Triborate
(Elsevier Science Bv, 2011) Depci, Tolga; Ozbayoglu, Gulhan; Yilmaz, Aysen
Lithium triborate (LiB(3)O(5)) was synthesized by high temperature solid-state reaction method, and then rare earth oxides were doped into LiB(3)O(5) to enhance its thermoluminescent (TL) properties. The identification and characteristics of the obtained compounds were determined by X-ray diffraction (XRD), Fourier transform infrared (FTIR) analyses, differential thermal analyses (DTA) and scanning electron microscopy (SEM). The glow curves were obtained using a thermoluminescent (TL) reader. The results revealed that all the rare earth oxides were not good activators for lithium triborate and the obtained compounds could not be used for dosimetric applications.