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Öğe Adsorption of p-nitrophenol on pyrophyllite(Parlar Scientific Publications (P S P), 2003) Erdemoglu, MThe adsorption capacity of pyrophyllite for removal of p-nitrophenol from aqueous solutions has been studied. FTIR spectroscopic data were evaluated to explain the adsorption mechanism. Adsorption isotherms were modelled according to Freundlich and Langmuir. The Freundlich constant, a, was calculated as 0.679 implying that increased adsorption modifies the surface, giving rise to increase the capacity. According to the computed value of the separation parameter, R-L, adsorption of p-nitrophenol on pyrophyllite is favourable and experimenttally proved to predict the shape of the Langmuir isotherm (0< R-L <1).Öğe Carbothermic reduction of high-grade celestite ore to manufacture strontium carbonate(Inst Mining Metallurgy, 1998) Erdemoglu, M; Canbazoglu, M; Yalçin, HThe conversion of celestite (SrSO4) to strontium sulphide (SrS) by the carbothermic reduction process was investigated as a route for the production of SrCO3 from high-grade Turkish celestite ores. Experiments were conducted in the temperature range 900-1400 degrees C and metallurgical-grade coke was used as the reducing agent. The effects of reduction temperature, amount of carbon and roasting time were studied. The products of reaction (black ash) were examined, mainly with the use of X-ray diffraction and name atomic absorption spectrometry. The results include data on recoverable Sr obtained as strontium carbonate precipitate. The conversion reaction is complete at 1300 degrees C, and it begins at lower temperatures. In addition to sulphate-sulphide conversion, all alkali earth metals found in the ore can be transformed to carbides in the process of reduction, especially when the roasting time and amount of carbon added to concentrate are increased. The reduction reaction seems to be very fast and it is concluded that the manufacture of SrCO3 is feasible from the roasted product.Öğe Characterization and photocatalytic properties of TiO2-nanosols synthesized by hydrothermal process at low temperature(Elsevier, 2006) Sayilkan, F; Asiltürk, M; Erdemoglu, S; Akarsu, M; Sayilkan, H; Erdemoglu, M; Arpaç, ETransparent nanocrystalline pure anatase titania (nano-TiO2) was synthesized by hydrothermal process at 200 degrees C. Photocatalytic activity of the nano-TiO2 as in the form of sol was tested for degradation of Methylene Blue (MB) and Reactive Red 120 (RR-120) in aqueous solutions. Structural and physico-chemical properties of the nano-TiO2 were characterized using powder XRD, SEM, BET, FTIR and elemental analyses. Complete photodegradation of RR-120 was successfully achieved by aid of the nano-TiO2 whereas NIB was not degraded, maybe because of reversible color change in nano-TiO2 sol/MB mixture after the LTV irradiation was stopped. Potocatalytic activity of the synthesized the nano-TiO2 for degradation of RR-120 was compared with Degussa P-25 at optimum conditions determined for RR-120. It was found that the nano-TiO2 can be repeatedly used with higher photocatalytic activity than Degussa P-25. (c) 2005 Elsevier B.V All rights reserved.Öğe Characterization of the hydrothermally synthesized nano-TiO2 crystallite and the photocatalytic degradation of Rhodamine B(Elsevier, 2006) Asiltürk, M; Sayilkan, F; Erdemoglu, S; Akarsu, M; Sayilkan, H; Erdemoglu, M; Arpaç, EPure anatase-TiO2 nanoparticles with 8 nm average crystallite size was synthesized hydrothermally at 200 degrees C in 2 h. The structural and physicochemical properties of nano-TiO2 were determined by powder XRD, FT-IR, BET and SEM analyses. The behavior of anatase nano-TiO2 in catalytic degradation of Rhodamine B (RB) dye in transparent nano-TiO2 sol under UV-light was examined as a function of irradiation power of UV-Iight, irradiation time, amount of nano-TiO2 and initial RB concentration in the sol. Rhodamine B was fully degraded with the catalysis of the nano-TiO2 in a short time as low as 60 min. Photocatalytic activity of the nano-TiO2 for degradation of RB was compared with Degussa P-25 at optimum catalysis conditions determined for the nano-TiO2. It was found that, when compared to Degussa P-25, the nano-TiO2 could be repeatedly used with increasing photocatalytic activity. It was found that the photodegradation obeys the pseudo first-order reaction kinetics with the rate constant of 0.0658 min(-1), and the half period t(1/2) was 10.53 min. (c) 2005 Elsevier B.V. All rights reserved.Öğe The effect of grinding on pyrophyllite flotation(Pergamon-Elsevier Science Ltd, 2002) Erdemoglu, M; Sarikaya, MThe effects of dry grinding on flotation recovery of pyrophyllite were investigated using an alcohol type frother. Before and after dry grinding for several periods, pyrophyllite was examined using DTA-TG, XRD, FTIR analyses and flotation tests. It was concluded that dry grinding for longer times affects the flotation recovery of pyrophyllite, since the crystal structure is distorted by mechanical treatment. (C) 2002 Elsevier Science Ltd. All rights reserved.Öğe Investigations on high gradient magnetic separation processes in rheological media(A A Balkema Publishers, 2000) Sarikaya, M; Erdemoglu, M; Abbasov, TOne of the problems encountered during the separation of suspensions which have various physical and chemical properties in High Gradient Magnetic Separators (HGMS) is the difference of their rheological properties. In the theory and practice of high gradient magnetic separation, the results obtained by the investigation of this problem are seldom and not enough. On the other hand, rheological properties of suspensions used in separation processes affect the efficiency of magnetic separation. Therefore, in order to get automation, improve the control of separation processes and determine the technological and economical parameters of the magnetic separators, it is necessary to take into consideration the rheological properties of the separated mediums. In this paper, by considering the rheological properties of suspensions, the investigation of the trajectory modelling of the particles in the magnetic separators has been presented. Ferromagnetic wires were used as matrix elements. In order to calculate the efficiency of the separator, analytical expressions were obtained by means of the fact that magnetic particles are collected on a magnetised wire. An integral expression of overall separator efficiency was determined by explaining the movement of a particle on a single magnetised wire. The obtained results have been illustrated by using appropriate graphics.Öğe The leaching of celestite in sodium sulfide solution to produce strontium carbonate(A A Balkema Publishers, 2000) Erdemoglu, M; Sarikaya, M; Canbazoglu, MThe leaching of celestite (SrSO4) with sodium sulfide (Na2S) solution was investigated from the point of strontium carbonate production. Experiments were carried out to explain the conversion mechanism of celestite to strontium disulfide (SrS2) in sodium sulfide solution. Leaching temperature was held constant and the effect of stirring rate, particle size and concentration of Na2S on the conversion of celestite were studied. The product from alkali leaching was leached with HCl to dissolve the leach product, strontium disulfide. Acidic leach liquid was, then, reacted with sodium carbonate solution to precipitate strontium carbonate. It was concluded that the conversion is based on the fact that a new compound having lower solubility is formed on the mineral surface in the system SrSO4, Na2S and H2O and that the rate of conversion mainly depends on the sodium sulfide concentration. The results showed that leaching of celestite in Na2S solution for conversion to strontium disulfide and production of strontium carbonate by using this chemical are possible processes.Öğe Leaching of celestite with sodium sulfide(Taylor & Francis Inc, 2006) Erdemoglu, M; Sarkaya, M; Canbazoglu, MLeaching of celestite mineral, SrSO4 , with sodium sulfide, Na2S, was investigated from the point of strontium carbonate, SrCO3, production. Experiments were carried out to explain the conversion mechanism of celestite to strontium disulfide, SrS2, in Na2S solution. Effects of stirring speed, particle size, and concentration of Na2S on conversion were studied at constant temperature and solid-to-liquid ratio. The results showed that the rate of conversion mainly depends on Na2S concentration. It was concluded that leaching of celestite in Na2S solution for conversion to SrS2 is possible but slow.Öğe The leaching of SrS with water and the precipitation of SrCO3 from leach solution by different carbonating agents(Elsevier Science Bv, 1998) Erdemoglu, M; Canbazoglu, MThe leaching of strontium sulfide (SrS) with water was investigated, and a comparison of Na2CO3 with CO2 as a carbonating agent for the precipitation of SrCO3 from leach solution was done. The effects of variables for leaching-temperature, retention time and solid to liquid ratio, and the effects of variables for precipitation-carbonation time, temperature, amount of carbonating agent and addition of oxygen to carbon dioxide, were studied. It was concluded that leaching of strontium sulfide is mainly dependent on the solubility of strontium hydroxide; however, SrS decomposes easily in hot water to give the hydrosulfide and the hydroxide. As a carbonating agent, Na2CO3 provides higher precipitation rates and higher strontium recovery but low SrCO3 grade, whereas precipitation with CO2 gives a high purity of product which is sufficient for most of the uses of SrCO3. It was also found that oxygen, when used together with carbon dioxide in the carbonation column, increases the strontium recovery and decreases the carbonation time. (C) 1998 Elsevier Science B.V. All rights reserved.Öğe Natural pyrophyllite and M(OR)x based MxOy powders as new adsorbents for heavy metal adsorption(Trans Tech Publications Ltd, 2004) Erdemoglu, M; Sayilkan, F; Erdemoglu, S; Sener, S; Akarsu, M; Sayilkan, HHeat treated hydrolysis-condensation products of aluminiumtri-sec-butoxide (Al(OBus)(3)) and alcohol modified Al(OBus)(3) were synthesised by sol-gel process. These synthetic powders, natural pyrophyllite and their 3-mercaptoprophyltrimethoxysilane coated forms were utilised as adsorbents for the removal of Cu(II) ions from aqueous solutions. The adsorption increased when natural and synthetic powders coated with SH-Si were used. It was concluded that the dried powders obtained from the hydrolysis-condensation product of Al(OBus)(3) and its alcohol modified form, and coated pyrophyllite would substitute for Amberlite IR 120 Na form resin.Öğe Organo-functional modified pyrophyllite: preparation, characterisation and Pb(II) ion adsorption property(Elsevier, 2004) Erdemoglu, M; Erdemoglu, S; Sayilkan, F; Akarsu, M; Sener, S; Sayilkan, HSurface modification of clay minerals has become increasingly important for improving the practical applications of clays such as fillers and adsorbents. In this study, the surface of pyrophyllite mineral was modified by coating with 3-(2-aminoethylamino) propyl-methyidimethoxysilane (APMDS) coupling agent and utility of the APMDS-modified pyrophyllite was investigated as an adsorbent for removal of Pb(II) ions from aqueous solutions. XRD, FT-IR and SEM analysis were used to characterise the surface modification and it was suggested that hydrogen bonding takes place between the hydroxyl groups and/or oxygen atoms within the structure of pyrophyllite and hydroxyl groups of APMDS. The APMDS-modified pyrophyllite adsorbed approximately 93% of Pb(II) ions at an initial concentration of 20 mg/l, while natural pyrophyllite did only 35% under the same conditions. The adsorption of Pb(II) increased with increasing pH and reached a maximum value in the pH range 6.5-7. The effects of various factors on the adsorption, such as pH of the solution, contact time, amount of adsorbent and initial Pb(II) concentration, were studied. The adsorption isotherm has been determined and data have been analysed according to the Langmuir model and found to be favourable, i.e., the separation parameter is less than unity (R-L < 1). (C) 2003 Elsevier B.V. All rights reserved.Öğe Production of SrCO3 by black ash process: Determination of reductive roasting parameters(A A Balkema, 1996) Erdemoglu, M; Canbazoglu, M[Abstract Not Available]Öğe Some aspects of magnetic filtration theory for removal of fine particles from aqueous suspensions(Taylor & Francis Inc, 2006) Sarikaya, M; Abbasov, T; Erdemoglu, MThe magnetic filtration theory was evaluated to intensify the filtration of industrial fluids by magnetic filters. Effects of filtration velocity and external magnetic field intensity on filter performance were investigated and the dependence of the logarithmic efficiency coefficient on filtration velocity was questioned. It was concluded that change in the magnetic susceptibility of the dispersion particles, caused by external magnetic field, and change in the flow rate properties of the liquid alongside the filter pores are the most essential factors to be considered in the design, development, and modeling of magnetic filtration systems in various industrial areas.Öğe Surface modification of pyrophyllite with amino silane coupling agent for the removal of 4-nitrophenol from aqueous solutions(Academic Press Inc Elsevier Science, 2004) Sayilkan, H; Erdemoglu, S; Sener, S; Sayilkan, F; Akarsu, M; Erdemoglu, MThe surface of naturally hydrophobic mineral pyrophyllite was modified to hydrophilic by treatment with prehydrolyzed N-(2-aminoethyl)3-ammopropyltrimethoxysilane (APEO) coupling agent to prepare a novel and effective adsorbent for the removal of 4-nitrophenol (4-NP) from aqueous solutions. XRD, FTIR, and SEM analyses were used to characterize the surface modification. It was found that after the grafting procedure, heat treatment at 110 degreesC results in condensation reaction between the OH groups of the APEO molecule and the hydroxyl groups and/or oxygen atoms on the pyrophyllite surface and the adsorption of 4-NP by APEO-modified pyrophyllite involves interactions between dissociated 4-NP molecules and protonated amine groups of APEO molecules attached to the mineral surface. Adsorption equilibrium data for 4-NP adsorption on APEO-treated and untreated pyrophyllite were most satisfactorily fitted using the Freundlich adsorption isotherm and adsorption capacity was found to be 0.268 mg/g for modified pyrophyllite whereas it was only 0.105 mg/g for untreated pyrophyllite. (C) 2004 Elsevier Inc. All rights reserved.
