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Bulunan: 15 Adet 0.001 sn
Koleksiyon [7]
Tam Metin [1]
Yayın Türü [2]
Yazar [15]
Yayın Yılı [9]
Konu Başlıkları [20]
Yayıncı [8]
Yayın Dili [2]
Dergi Adı [13]
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 )

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

Adsorption and interactions of the bovine serum albumin-double walled carbon nanotube system

Kopac T. | Bozgeyik K. | Flahaut E.

Article | 2018 | Journal of Molecular Liquids252 , pp.1 - 8

Adsorption and interactions of Bovine Serum Albumin (BSA) with Double Walled Carbon Nanotubes (DWNT) prepared by catalytic chemical vapor deposition (CCVD) synthesis were studied. Adsorption kinetics and equilibrium were investigated by means of in situ UV-spectroscopy. The extent of adsorption at different temperatures was determined at the end of a 420-min adsorption period. The adsorption equilibrium experiments were performed using various amounts of nanotubes at pH 4 and 40 °C, and the adsorption parameters were evaluated comparing the experimental data with models such as the Freundlich and Langmuir isotherms. The maximum prot . . .ein adsorption capacity (Q0) of DWNT was determined as 1221 mg·g- 1. The effect of temperature on the adsorption rate experiments was investigated for constant amount of adsorbent at pH 4. Adsorption kinetics followed the pseudo-first-order rate. Zeta potential measurements were performed with respect to solution pH for understanding the protein-surface interactions. The interactions between positively charged BSA molecules with negatively charged DWNT at pH 4 were found to be electrostatic attractions. Thermodynamic parameters, ?H0 and ?S0 were found as 9.40 kJ·mol- 1 and 321.5 J·mol- 1 K- 1, respectively. ?H0 value indicated that BSA adsorption on DWNT was a physisorption process. © 2017 Elsevier B.V Daha fazlası Daha az

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

Equilibrium, Kinetics, and Thermodynamics of Bovine Serum Albumin Adsorption on Single-Walled Carbon Nanotubes

Kopac T. | Bozgeyik K.

Article | 2016 | Chemical Engineering Communications203 ( 9 ) , pp.1198 - 1206

We investigated the equilibrium, kinetics, and thermodynamics of bovine serum albumin (BSA) adsorption on single-walled carbon nanotubes (SWNTs) from aqueous solutions with different pH and temperatures. We analyzed the experimental adsorption equilibrium and kinetic data to evaluate the adsorption characteristics of SWNTs for BSA. The results show that the effects of pH and temperature were important. Moreover, the adsorption isotherm data of BSA on SWNTs are consistent with the Langmuir and Freundlich models, while the kinetics can be expressed by the pseudo-first-order and the intraparticle diffusion rate models. The maximum prot . . .ein adsorption capacity of SWNTs, which have a surface area of 191.2 m2/g, was found to be 609.8 mg g-1 at pH 4 and 40°C, and this was the highest value obtained among our previous studies examined with various metal oxides. In addition, the zeta potential measurements were examined to understand the effects of charge density of the surface and the protein on the adsorption process. Thermodynamic analysis results indicate that the nature of adsorption changes with pH. SWNTs were found to be effective for BSA adsorption. © 2016, Copyright © Taylor & Francis Group, LLC Daha fazlası Daha az

Synthesis of multi-walled carbon nanotube-zirconia composite and bovine serum albumin adsorption characteristics

Bozgeyik K. | Kopac T.

Conference Object | 2017 | Materials Science Forum900 MSF , pp.27 - 31

Multi-walled carbon nanotube-zirconia composite (MWNT-ZrO2) was synthesized by a simple in situ chemical precipitation method. Adsorption of bovine serum albumin (BSA) from aqueous solution on the MWNT-ZrO2 composite was studied using batch technique at different pH and temperatures. The adsorption equilibrium and kinetic data were analzed using different models. The adsorption isotherm data could be described by both of the Langmuir and Freundlich adsorption models. Adsorption kinetics followed the pseudo-first-order rate model. MWNT loading improved the surface and the BSA adsorptive characteristics of zirconia. © 2017 Trans Tech . . .Publications, Switzerland 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

Transport of Lead (Pb2+) Ions through silty-clayey soils under acidic conditions

Genç, Ayten | Ulupınar, Elif

Article | 2010 | Transport in Porous Media84 ( 3 ) , pp.699 - 709

This study aimed to identify effects of pH on the transport of Pb2+ ions through a saturated silty-clayey soil layer by using advection-dispersion equation (ADE). The predictive accuracy of the solution of ADE depends on the proper determination of the retardation by adsorption and, therefore, the adsorption mechanism of lead onto silty-clayey soil was investigated first by performing batch equilibrium experiments. These results showed that the sorption mechanism of lead onto silty-clayey soil depended on pH and could be best described by the Langmuir isotherm. Based on the results of the sequential experiments, it was also conclude . . .d that the pH dependent charges in silty-clayey soil were mainly associated with the surfaces of carbonates and the specific adsorption of lead ions. The numerical solutions of the combined form of ADE with the Langmuir isotherm indicated that the migration profiles of lead in silty-clayey soil were a strong function of the parameters of the Langmuir isotherm rather than the infiltration velocity. © 2010 Springer Science+Business Media B.V Daha fazlası Daha az

Investigation of the interactions and adsorption of ovalbumin with titanium dioxide and zirconia surfaces [Ovalbüminin titanyum dioksit ve zirkonya yüzeylerle etkileşimi ve adsorpsiyonunun araştirilmasi]

Kopaç T. | Kulaç E.

Article | 2017 | Journal of the Faculty of Engineering and Architecture of Gazi University32 ( 2 ) , pp.489 - 497

Knowing the interactions between the protein molecules and the biomaterial surfaces is important in a number of applications in biomedical technologies and materials engineering. The lack of knowledge on this topic due to the complexity of the protein molecular structures and their adsorption necessitates carrying out research work in order to solve the problems related with the protein-surface interactions. Protein adsorption is influenced by many parameters such as the properties of proteins, pH, concentration, ionic strength and temperature. The aim of this study is to investigate the Ovalbumin adsorption from aqueous solutions o . . .n TiO2 and ZrO2, to study the effects of solution pH, temperature and adsorbent dosage on adsorption; to investigate the adsorption kinetics, protein-metal oxide interactions, and to determine the conditions controlling the adsorption. The interactions and adsorption of Ovalbumin protein with TiO2 and ZrO2 powders in solution environment were investigated in a batch adsorption system. Adsorption experiments were carried out in pH 5, 6.4, 8 environment at 20, 25, 30 °C. The effect of adsorbent dosage was also investigated by the addition of different amounts of TiO2/ZrO2 in the range 0.5-1.0 g/L. Results have shown that the adsorbed amount of Ovalbumin increases with increasing temperature and adsorbent dosage, but decreases with increasing pH. The increase of contact surface with increasing adsorbent dosage increases protein adsorption. The zeta potential measurement results supported that the interactions between Ovalbumin with TiO2 and ZrO2 were higher at pH 5, which is close to the isoelectric point of protein. The adsorption of Ovalbumin onto TiO2 and ZrO2 at different temperatures and solution pH conditions followed first order kinetics with a better fit for both adsorbents Daha fazlası Daha az

Removal of Pb(II) and Ni(II) ions from aqueous solution by peat

Sutcu H.

Article | 2007 | Fresenius Environmental Bulletin16 ( 12:00 AM ) , pp.1551 - 1555

The purpose of this study is to investigate the tendency of peat to adsorb Pb(II) and Ni(II) ions from an aqueous solution. The experiments conducted aimed at studying the effect of initial metal ion concentration, adsorbent dosage, aqueous solution pH and aqueous solution temperature in the single-component aqueous solutions. In addition, a binary-component aqueous solution was used to investigate the effects of contact time and desorption. According to the results of the experiments carried out under these conditions, it has been established that the optimum peat dosage is 2 g peat/L, the optimum pH 6, the optimum initial metal io . . .n concentration 5 mg/L Pb(II) and 5 mg/L Ni(II), the aqueous solution temperature 20°C, and contact time 60 min. According to the results of all experimental conditions, the adsorption capacity was found to be Pb(II)>Ni(II). It has been established that the adsorption isotherm is well-suited to the Langmuir isotherm. © by PSP 2007 Daha fazlası Daha az

Effect of pH and temperature on the adsorption of bovine serum albumin onto titanium dioxide

Kopac T. | Bozgeyik K. | Yener J.

Article | 2008 | Colloids and Surfaces A: Physicochemical and Engineering Aspects322 ( 01.Mar ) , pp.19 - 28

The effects of pH and temperature on the equilibrium and the kinetics of bovine serum albumin (BSA) adsorption onto titanium dioxide (TiO2) were investigated. Adsorption rate and equilibrium experiments were carried out at pH conditions of 4, 5, 10 and in a temperature range of 20-40 °C. Adsorption rate was increased with decreasing pH and increasing temperature. The Langmuir isotherm constants corresponding to adsorption capacity, Q0, were 35.8, 40.0 and 42.6 mg/g for 20, 30 and 40 °C and pH 4; and 24.5, 29.1 and 33.4 mg/g for 20, 30, 40 °C and pH 5, respectively. The BSA adsorption capacities of TiO2 were higher for pH 4 at 40 °C. . . . Adsorption of BSA on TiO2 at different pH and temperatures was found to be first order kinetics. At pH 4, k1 has values of 0.018 and 0.019 min-1 at 20 and 40 °C, respectively. For pH 5, k1 is 0.013 min-1 at 20 °C and 0.019 min-1 at 40 °C. The first order rate constants are higher at pH 4 than the values at pH 5. Higher values of the adsorption rate constants at pH 4, could be due to the change of pore structure of TiO2 or denaturation by conformational change of BSA with increasing pH. © 2008 Elsevier B.V. All rights reserved Daha fazlası Daha az

Effect of surface area enhancement on the adsorption of bovine serum albumin onto titanium dioxide

Kopac T. | Bozgeyik K.

Article | 2010 | Colloids and Surfaces B: Biointerfaces76 ( 1 ) , pp.265 - 271

The equilibrium and the kinetics of BSA adsorption onto specific surface area changed TiO2 by heat treatment were studied. The TiO2 was treated at 100 and 200 °C for 24 h. The specific surface areas of TiO2 characterized by BET method were measured as 48.9 m2/g and 53.0 m2/g for 100 and 200 °C, respectively. The adsorption rate and the equilibrium experiments were carried out at pH 4 for 40 °C. The rate kinetics for the adsorption of BSA was best fitted with the pseudo-first-order kinetic model. The equilibrium process was described by the Langmuir and Freundlich isotherm models. The adsorption capacities (Q0) calculated from the La . . .ngmuir isotherm model were 40.6 and 44.4 mg/g for heat-treated TiO2 at 100 and 200 °C, respectively. The adsorption of BSA increased with increasing surface area of TiO2. The zeta potential values of the 100- and 200 °C-treated TiO2 were found as -2.57 mV and 0.39 mV, respectively, showing that the interaction between TiO2 with BSA increased with increasing temperature of heat treatment for TiO2. © 2009 Elsevier B.V. All rights reserved Daha fazlası Daha az

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