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Bulunan: 12 Adet 0.012 sn
Koleksiyon [3]
Tam Metin [1]
Yayın Türü [1]
Yazar [17]
Yayın Yılı [8]
Konu Başlıkları [20]
Yayıncı [8]
Yayın Dili [2]
Dergi Adı [9]
Preparation of activated carbons from Zonguldak region coals by physical and chemical activations for hydrogen sorption

Kopac T. | Toprak A.

Article | 2007 | International Journal of Hydrogen Energy32 ( 18 ) , pp.5005 - 5014

Activated carbons were prepared by physical and chemical activations from coals collected from two mines (Kilimli and Armutcuk) in Zonguldak region, Turkey under different conditions. Ash content was reduced considerably by use of HCl and HF treatments. Pyrolytic thermal treatments in a temperature range of 600-900 {ring operator} C under N2 flow and chemical treatments using different chemical agents such as KOH, NH4Cl, ZnCl2 were applied to the coal samples from the two mines. N2 adsorption isotherms were obtained at 77.4 K for the thermally and the chemically treated samples and the data were used for the evaluation of the specif . . .ic surface area, total pore volumes and the average pore sizes of the samples. Higher surface area values were obtained from Kilimli coal samples than Armutcuk. The BET surface area of the Kilimli coal samples which were initially have a value of 1.20 m2/g were increased to 52.62 m2/g after pyrolytic heat treatments at 800 {ring operator} C and increased to a value of 830.5 m2/g by treating the coals with KOH + NH4 Cl mixture at 750 {ring operator} C followed by oxidation of the samples mixed with ZnCl2. The activated carbon samples were prepared for the purpose of their evaluation in hydrogen sorption studies. © 2007 International Association for Hydrogen Energy Daha fazlası Daha az

Non-isobaric adsorption analysis of SO2 on molecular sieve 13X and activated carbon by dynamic technique

Kopaç T.

Article | 1999 | Chemical Engineering and Processing: Process Intensification38 ( 1 ) , pp.45 - 53

Sulfur dioxide is one of the major pollutants resulting from fuel combustion. In this study non-isobaric pulse chromatography was used for the investigation of the adsorption properties of sulfur dioxide on molecular sieve 13X and activated carbon. The experimental procedure consists of introducing a pulse of sulfur dioxide on the inlet of a column packed with molecular sieve 13X and activated carbon adsorbents and measuring the concentration versus time response peak leaving the other end of the column. Adsorption equilibrium constants were calculated using the moment analysis of the chromatographic peaks. Non-isobaric pulse chroma . . .tographic technique necessitates the use of high carrier gas flow rates which avoids the tailing of the response peaks and reduces considerably the uncertainty in the measurement of the moments. The adsorption of sulfur dioxide was investigated in a temperature range of 353-453 K with the activated carbon, which is a typical temperature range of desulfurization of flue gas, and in a temperature range of 523-673 K with molecular sieve 13X. Adsorption equilibrium constants of sulfur dioxide were found to decrease considerably with increasing temperature. At 453 K, the adsorption equilibrium constant was found to be 18.78, whereas it has a value of 330.2 at 353 K with the activated carbon. At 673 K, the adsorption equilibrium constant was found to be 11.52, whereas it has a value of 167.82 at 523 K with molecular sieve 13X. Heat of adsorption of sulfur dioxide on molecular sieve 13X and the activated carbon was determined as -12.4 and -8.99 kcal mol-1, respectively.Sulfur dioxide is one of the major pollutants resulting from fuel combustion. In this study non-isobaric pulse chromatography was used for the investigation of the adsorption properties of sulfur dioxide on molecular sieve 13X and activated carbon. The experimental procedure consists of introducing a pulse of sulfur dioxide on the inlet of a column packed with molecular sieve 13X and activated carbon adsorbents and measuring the concentration versus time response peak leaving the other end of the column. Adsorption equilibrium constants were calculated using the moment analysis of the chromatographic peaks. Non-isobaric pulse chromatographic technique necessitates the use of high carrier gas flow rates which avoids the tailing of the response peaks and reduces considerably the uncertainty in the measurement of the moments. The adsorption of sulfur dioxide was investigated in a temperature range of 353-453 K with the activated carbon, which is a typical temperature range of desulfurization of flue gas, and in a temperature range of 523-673 K with molecular sieve 13X. Adsorption equilibrium constants of sulfur dioxide were found to decrease considerably with increasing temperature. At 453 K, the adsorption equilibrium constant was found to be 18.78, whereas it has a value of 330.2 at 353 K with the activated carbon. At 673 K, the adsorption equilibrium constant was found to be 11.52, whereas it has a value of 167.82 at 523 K with molecular sieve 13X. Heat of adsorption of sulfur dioxide on molecular sieve 13X and the activated carbon was determined as - 12.4 and - 8.99 kcal mol-1 Daha fazlası Daha az

Adsorption of methylene blue from aqueous solutions by activated carbon prepared from hazelnut husk using zinc chloride

Karaçetin G. | Sivrikaya S. | Imamo?lu M.

Article | 2014 | Journal of Analytical and Applied Pyrolysis110 ( 1 ) , pp.270 - 276

In this study, activated carbon prepared from hazelnut husk (HHAC) using zinc chloride as chemical activating agent was characterized by FT-IR spectroscopy, BET surface area, Boehm titration, SEM and elemental analyses. During adsorption from aqueous solution of methylene blue (MB) studied by the batch method, effects of many variables, including solution pH, agitation time, temperature and initial concentration were investigated. It was established that MB adsorption reached equilibrium at 120 min at pH 7.0 as the appropriate value and is more compatible with Langmuir adsorption isotherm with respect to Freundlich. MB adsorption ca . . .pacity of HHAC was found to be 476.2 mg g-1 and MB adsorption kinetics corresponds well with pseudo second order model. Thermodynamic studies revealed that MB adsorption is a spontaneous and endothermic process. © 2014 Elsevier B.V. All rights reserved Daha fazlası Daha az

Synthesis and characterization of KOH/boron modified activated carbons from coal and their hydrogen sorption characteristics

Kopac T. | Kırca Y. | Toprak A.

Article | 2017 | International Journal of Hydrogen Energy42 ( 37 ) , pp.23606 - 23616

Activated carbons from bituminous coal taken from the area of Zonguldak Kilimli region in Turkey were synthesized by chemical activation using a mixed combination of KOH and as a boron source borax decahydrate. The modification process consists of chemical activation of the demineralized coal with KOH (KOH/coal:4/1) and various concentrations of borax decahydrate solutions (0.025–0.1 M). Textural properties such as surface area and pore structure were studied by volumetric methods using N2 adsorption data at 77.4 K (P/P0 = 0–1). The samples obtained have high microporosity, in the form of irregular structures. The EDAX spectra indic . . .ate that Boron heteroatoms are attached to surface of AC41, and as BDH concentration increases from 0.025 M to 0.1 M, higher atomic percent of boron is accumulated at the surfaces. AC41 exhibits amorphous structures, whereas BDH modified AC41 consists of predominantly amorphous structure and disordered graphitic carbon. Among the synthesized boron modified samples, the highest surface area, total pore volume and average pore diameters were found for the 0.025 M_BDH-AC41 sample. As the BDH concentration increases, the volume of N2 adsorbed decreases. Surface area of CC and AC41 samples were 52.62 and 2228 m2/g, respectively, whereas surface area of the boron modified samples were found in the range of 2190–2704 m2/g. Hydrogen sorption capacities of the KOH/boron modified samples were found in the range between 2.08 and 3.74% wt. Hydrogen sorption capacity of AC41 obtained was 4.11% wt. Increasing boron concentration resulted in the decrease of hydrogen sorption capacities. Boron modified activated carbons were prepared successfully from coal samples by chemical activation using a mixed combination of KOH and BDH. © 2017 Hydrogen Energy Publications LL Daha fazlası Daha az

Dynamic analysis of sorption of Methylene Blue dye on granular and powdered activated carbon

Yener J. | Kopac T. | Dogu G. | Dogu T.

Article | 2008 | Chemical Engineering Journal144 ( 3 ) , pp.400 - 406

Removal of dyes and pigments from wastewaters of dying and printing industries is a major environmental issue. Sorption rate and equilibrium parameters of Methylene Blue on granular and powdered activated carbons were investigated in a batch adsorber. Due to the significance of pore diffusion resistance and partial closure of pore mouths by dissociatively chemisorbed dyes, both sorption rate and sorption capacity values evaluated for granular carbon were lower than the corresponding values for powdered activated carbon. Concentration independent effective pore diffusivity values in the order of magnitude of 10-9 cm2/s were obtained . . .by the moment analysis of a proposed diffusion model (Model 1). © 2008 Elsevier B.V. All rights reserved Daha fazlası Daha az

Effect of Surface Area and Micropore Volume of Activated Carbons from Coal by KOH, NaOH and ZnCl2 Treatments on Methane Adsorption

Toprak A. | Kopac T.

Article | 2019 | International Journal of Chemical Reactor Engineering17 ( 6 ) , pp.400 - 406

This paper investigates the methane adsorption characteristics of activated carbons produced from coal by activation with KOH, NaOH and ZnCl2 treatments at different agent to coal ratios (1:1-6:1) and temperatures (600-800°C) under N2 flow. CH4 adsorption capacities and desorption behaviors of the activated carbons were examined at 0°C and 25°C. The relationship between CH4 adsorption characteristics and surface properties of activated carbons, such as BET surface area determined by N2 adsorption at-196°C, and micropore volume determined by CO2 adsorption at 0°C were investigated. Optimal results for CH4 adsorption at 0°C and 25°C w . . .ere obtained for the activated carbon samples obtained with KOH treatment at 800°C at 4:1 ratio, as 2.67 and 1.12 mmol/g, respectively. The results have shown that CH4 adsorption increased proportionally with micropore volume of activated carbons, whereas BET surface area does not exhibit an exact consistency. CH4 adsorption-desorption isotherms at 25°C have shown that an increase in mesopore formation caused a decrease in adsorption; but allowed desorption to be reversible. Higher methane adsorption capacities were obtained from activated carbons produced from coal by various treatments in this study than most of the reported results in literature at the similar conditions, indicating the suitability of the evaluated materials for industrial applications of methane storage. © 2019 Walter de Gruyter GmbH, Berlin/Boston 2019 Daha fazlası Daha az

The adsorption of lead, copper and nickel ions from aqueous solutions on activated carbon produced from bituminous coal

Sutcu H. | Dural A.

Article | 2007 | Fresenius Environmental Bulletin16 ( 3 ) , pp.235 - 241

In this study, activated carbon was produced using three different chemical reagents (KOH, NaOH and LiOH). The BET surface area of the activated carbon obtained by using KOH was found to be 588 m2 g-1, and it was selected as the most suitable one for heavy metal adsorption from an aqueous solution. During the experiments, an investigation was carried out to examine the effects of parameters, such as the contact time, the aqueous solution pH, the activated carbon dosage, the initial metal concentration and the aqueous solution temperature, on adsorption. It was established that activated carbon exhibited an adsorption capacity in the . . . order of Pb(H)>Cu(H)>Ni(II). The adsorption isotherms of Pb(II), Cu(II) and Ni(II) ions were established to be in accordance with the Langmuir and Freundlich isotherms. In the adsorption process, the enthalpy variations were found to be -20.4 kJ/mol, -17.2 kJ/ mol and -17.9 kJ/ mol, respectively. © by PSP. 2007 Daha fazlası Daha az

Dynamic analysis of sorption of hydrogen in activated carbon

Erdogan F.O. | Kopac T.

Article | 2007 | International Journal of Hydrogen Energy32 ( 15 SPEC. ISS. ) , pp.3448 - 3456

Hydrogen storage and adsorption studies in carbon materials have been of great concern in recent years. Hydrogen is thought to be an ideal energy source because of causing no pollutants or greenhouse gases during combustion unlike the fossil fuels. In this study, sorption characteristic of H2 and N2 gases in activated carbon having three different particle sizes were investigated in a temperature range of 303-473 K using a dynamic technique. The experimental procedure consist of introducing a pulse of H2 and N2 on the inlet of a column packed with activated carbon samples and measuring the concentration versus time response peak lea . . .ving the other end of the column. Adsorption equilibrium constants were evaluated using the moment analysis of the chromatographic peaks. At 473 K, the adsorption equilibrium constant for H2 on activated carbon having 4.76-0.85 mm particle size (ACI) was found to be 7.92 × 10- 4, whereas it has value of 1.83 × 10- 3 m3 / kg at 303 K. Heats of adsorption of H2 and N2 on ACI were determined as - 4.8 and - 11.6 kJ mol- 1, respectively. The values of heat of adsorption obtained indicate physical adsorption of H2 and N2 gases on the activated carbon samples used. © 2007 International Association for Hydrogen Energy Daha fazlası Daha az

Effect of KOH treatment on bituminous coal for the effective removal of Basic Blue 41 dye from aqueous solutions

Kopac T. | Sulu E. | Toprak A.

Article | 2016 | Desalination and Water Treatment57 ( 59 ) , pp.29007 - 29018

Activated carbons (ACs) were produced from Zonguldak region bituminous coal using physical and chemical techniques and evaluated for the removal of a textile dye, Basic Blue 41 from aqueous solutions. The color removal performance of ACs prepared by physical activation (PAC), chemical activation with KOH (CAC), and the commercial AC were compared; and the effects of adsorbent preparation method, temperature, and initial dye concentration on adsorption were studied. BET surface areas of the PAC, AC, and CAC were determined as 52.6, 824, and 1,312 m2 g-1, respectively. Micropore volume of PAC determined by DR method was 0.02 cm3 g-1, . . .whereas AC and CAC have values of 0.42 and 0.57 cm3 g-1. Thermal treatment with KOH resulted in enhancement of the porosity characteristics, particularly in micropores, and the surface area of the CAC samples. The batch adsorption experiments were carried out isothermally at 25–35°C. The values for the adsorption capacity Q0, determined from the Langmuir model at 25, 30, and 35°C were 96.4, 52.1, 54.7 mg g-1 for PAC; 262.5, 283.3, 293.3 mg g-1, for AC; and 420.2, 427.4, 460.8 mg g-1 for CAC, respectively. The increase in adsorption capacity with an increase in temperature for BB 41 onto CAC and AC indicated an endothermic chemisorption process, which was attributed to increased surface coverage at higher temperature and creation of reactive and active sites. For BB 41 adsorption onto PAC, the decrease in sorption capacity with increasing temperature indicated the exothermic behavior of the sorption process that is related to physisorption. The adsorption capacity of the obtained samples was found in the order of CAC > AC > PAC. Among the AC samples prepared by different methods, the highest value of the adsorption capacity obtained was 460.8 mg g-1 at 35°C for CAC. Kinetic data were adequately represented by the pseudo-first-order kinetic model. AC prepared from coal by CAC treatment was shown to be an effective adsorbent for the removal of BB 41. © 2016 Balaban Desalination Publications. All rights reserved Daha fazlası Daha az

Comparison of the adsorption behavior of Basic Red 46 textile dye on various activated carbons obtained from Zonguldak coal [Bazik Kirmizi 46 tekstil boyasinin Zonguldak kömüründen elde edilen farkli aktif karbonlar üzerinde adsorpsiyon davranişinin karşilaştirilmasi]

Kopaç T. | Sulu E.

Article | 2019 | Journal of the Faculty of Engineering and Architecture of Gazi University34 ( 3 ) , pp.1227 - 1240

The activated carbons obtained by physical and chemical activation techniques from Zonguldak-Kilimli region coal was used for the adsorption of a textile dye, Basic Red 46 from aqueous solutions. The effects of adsorbent preparation method, initial dye concentration and temperature on adsorption were investigated. The color removal performance of activated carbons prepared by physical activation (PAC), chemical activation with KOH (CAC) and the commercial activated carbon (AC) were compared. The batch adsorption experiments were carried out isothermally at 25, 30 and 35°C. The adsorption capacities at 25, 30 and 35°C were found as 6 . . .2.7, 23.1, 19.6 (PAC); 201.6, 215.1, 231.5 (AC); and 277.8, 307.7, 323.6 mg g- 1 (CAC), respectively. It was found that the CAC sample having the highest micropore and surface area obtained by thermal treatment with KOH had the highest adsorption capacity. The results have shown that the adsorption of BR 46 exhibited an endothermic character on CAC and AC, and exothermic character on PAC. Kinetic data were adequately fitted by the pseudo- first order kinetic model. The study has shown that activated carbon obtained by KOH activation of coal could be effectively used for the adsorptive removal of BR 46 textile dye from wastewaters. The activated carbon obtained from Zonguldak coal with low cost, non toxic character and excellent adsorption performance has a high potential for sustainable commercial applications. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved Daha fazlası Daha az

Production of granular activated carbons from loquat stones by chemical activation

Sütcü H. | Demiral H.

Article | 2009 | Journal of Analytical and Applied Pyrolysis84 ( 1 ) , pp.47 - 52

This paper describes the production of activated carbons by chemical activation with KOH and NaOH of the chars obtained through carbonization of loquat stones at 600 °C. The chars in the 1.0-2.0 mm size range were activated at carbonization temperatures ranging from 600 °C to 1000 °C, heating rate of 10 °C/min and a char/chemical agent mass ratio of 1/2 under nitrogen flow. In addition, activated carbons were prepared from chars in the 1.0-2.0 mm and

Adsorption of phenols and chlorophenols in wastewaters on activated carbon and dried activated sludge [Atiksulardaki fenol ve klorofenollerin aktif karbon ve kurutulmus aktif camura adsorpsiyonu]

Yener J. | Aksu Z.

Article | 1999 | Turkish Journal of Engineering and Environmental Sciences23 ( 2 ) , pp.93 - 104

One of the methods used for removal of phenols and chlorophenols from the wastewaters of petroleum refineries, coke, medicine, dye, plastics, pesticide, insecticide, and paper industry is the adsorption process. In this study, adsorption of phenol, o-chlorophenol and p-chlorophenol from aqueous solutions on to granular activated carbon and dried activated sludge was investigated as a function of pH, initial pollutant concentration and functional groups. Effects of these parameters on adsorption rates and yields were investigated. The Freundlich and Langmuir adsorption isotherms were used for the mathematical description of the adsor . . .ption equilibrium and the isotherm constants were determined for each pollutant.One of the methods used for removal of phenols and chlorophenols from the wastewaters of petroleum refineries, coke, medicine, dye, plastics, pesticide, insecticide, and paper industry is the adsorption process. In this study, adsorption of phenol, o-chlorophenol and p-chlorophenol from aqueous solutions on to granular activated carbon and dried activated sludge was investigated as a function of pH, initial pollutant concentration and functional groups. Effects of these parameters on adsorption rates and yields were investigated. The Freundlich and Langmuir adsorption isotherms were used for the mathematical description of the adsorption equilibrium and the isotherm constants were determined for each pollutant Daha fazlası Daha az

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