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AKTAŞ, SERDAR

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AKTAŞ

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SERDAR

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2015 - 20193
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End date: 2019 × Subject: KINETICS ×

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Now showing 1 - 3 of 3
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    PublicationOpen Access
    Studies of Gold Adsorption from Chloride Media
    (UNIV FED SAO CARLOS, DEPT ENGENHARIA MATERIALS, 2015-06) AKTAŞ, SERDAR; Morcali, Mehmet Hakan; Zeytuncu, Bihter; Ozlem, Eda; Aktas, Serdar
    In this paper, adsorption of gold from chloride media using commercial sorbent (Lewatit TP 214 (L-214)) and biomass residue (rice hull (RH)) were investigated. The different adsorption parameters, sorbent dosage, contact time, temperature and pH of solution on adsorption (%) were studied in detail on a batch sorption. Before the RH was activated, adsorption (%) was poor compared with L-214. However, after the RH was activated at 1000 degrees C under an argon atmosphere, the gold adsorption (%) increased four-fold. X-ray fluorescence (XRF) was used to explore the feasibility this material as an adsorbent for the removal of gold from aqueous solutions. The adsorption equilibrium data were best fitted with the Langmuir isotherm model. The maximum adsorption capacities, Q(max), at 25 degrees C were found to be 93.46 and 108.70 mg/g for the activated rice hull (ARH) and L-214, respectively. Thermodynamic calculations using Delta H degrees, Delta S degrees, Delta G degrees and E-a values indicate that the adsorption process was spontaneous and endothermic.
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    Production of Chromium Oxide from Turkish Chromite Concentrate Using Ethanol
    (WALTER DE GRUYTER GMBH, 2015) ÖZBEY, SEMİH; Aktas, S.; Eyuboglu, C.; Morcali, M. H.; Ozbey, S.; Sucuoglu, Y.
    In this study, the possibility of chromium extraction from Turkish chromite concentrate and the production of chromium oxide were investigated. For the -conversion of chromium(III) into chromium(VI), NaOH was employed, as well as air with a rate of 20 L/min. The effects of the base amount, fusing temperature, and fusing time on the chromium conversion percentage were investigated in detail. The conversion kinetics of chromium(III) to chromium(VI) was also undertaken. Following the steps of dissolving the sodium chromate in water and filtering, aluminum hydroxide was precipitated by adjusting the pH level of the solution. The chromium(VI) solution was subsequently converted to Cr(III) by the combination of sulfuric acid and ethanol. Interestingly, it was observed that ethanol precipitated chromium as chromium(VI) at mildly acidic pH levels, although this effect is more pronounced for K2Cr2O7 than Na2Cr2O7. On the other hand, in the strongly acidic regime, ethanol acted as a reducing agent role in that chromium(VI) was converted into Cr(III) whereas ethanol itself was oxidized to carbon dioxide and water. Subsequently, chromium hydroxide was obtained by the help of sodium hydroxide and converted to chromium oxide by heating at 800 degrees C, as indicated in thermo gravimetric analysis (TGA).
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    Oxidative dissolution of nickel matte in dilute sulfuric acid solutions
    (ELSEVIER, 2019) AKTAŞ, SERDAR; Morcali, Mehmet Hakan; Khajavia, Leili Tafaghodi; Aktas, Serdar; Dreisinger, David Bruce
    Nickel matte (Ni3S2) is the most common feedstock for producing nickel oxide and nickel metal in associated refineries. Nickel matte is produced from sulfide or laterite ores, and contains around 73 wt% nickel. This study investigated the dissolution parameters of nickel matte in dilute sulfuric acid media in the presence of air as oxidant with the goal of presenting a cost-effective process for leaching nickel matte. The dissolution experiments were carried out to examine the following effects: air flow rate, stirring speed, S/L ratio, acid concentration, reaction temperature, reaction time and the amount of ferrous sulfate added. Nickel extraction of 90% and cobalt extraction of 80% were achieved using dilute H2SO4 and sparging of air as a source of oxygen. To increase the dissolution percentage of the matte, ferrous sulfate addition was studied and the oxidation and reduction potential (ORP) was measured to investigate the effect of ferrous ions on nickel and cobalt recovery. The highest nickel dissolution percentage (95%) was observed with the initial addition of 1200 mg/L Fe (II). Characterization of samples has been carried out with quantitative X-ray diffraction (XRD) and scanning electron microscopy, along with an energy dispersive system (SEM-EDS).