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Adsorption of Basic Yellow 28 from aqueous solutions with clinoptilolite and amberlite

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

Article | 2006 | Journal of Colloid and Interface Science294 ( 2 ) , pp.255 - 264

The objective of this study was to investigate the adsorption of Basic Yellow 28 that is a cationic dye on clinoptilolite and amberlite XAD-4. Both equilibrium and batch rate adsorption in aqueous solutions of the dyestuff were investigated. Adsorption rate data were analysed using the pseudo-first order kinetic model of Lagergren and the pseudo-second order model to determine adsorption rate constants at 20, 30 and 40 °C. The adsorption equilibrium data were analysed using various adsorption isotherm models and the results have shown that adsorption behaviour of Basic Yellow 28 by clinoptilolite and amberlite could be described by . . .either Langmuir or Freundlich models. Langmuir adsorption isotherm constants corresponding to adsorption capacity, Q0, were found to be 59.6, 52.9 and 56.7 mg/g for clinoptilolite at 20, 30 and 40 °C, respectively. Lower adsorption capacities for Basic Yellow 28 on amberlite were obtained. The increase of adsorption rate constants with an increase in temperature for BY 28 adsorption on amberlite indicated chemisorption with dissociation and increased availability of sites due to higher penetration of adsorbing molecules into the pores. © 2005 Elsevier Inc. All rights reserved Daha fazlası Daha az

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

Temperature and alkaline hydroxide treatment effects on hydrogen sorption characteristics of multi-walled carbon nanotube-graphite mixture

Kopac T. | Erdogan F.O.

Article | 2009 | Journal of Industrial and Engineering Chemistry15 ( 5 ) , pp.730 - 735

Temperature and alkaline hydroxide treatment effects on the surface area and pore structure of the cathode deposit multi-walled carbon nanotube (MWCNT)-graphite mixture were investigated in a temperature range of 600-800 °C. Hydrogen sorption properties of the MWCNT-graphite mixture samples were studied by varying the alkaline hydroxide-activation temperature. Pore characterization of modified MWCNT-graphite mixture was performed with the observation of adsorption-desorption isotherms of N2 at 77 K. Hydrogen sorption of the non-treated and treated MWCNT-graphite mixture was carried out using a volumetric apparatus at 77 K. The highe . . .st surface area of the sample was obtained as 275 m2 g-1 by treatments with KOH at 600 °C. The increase in the specific surface area of MWCNT-graphite sample mixture was about 13 times. The maximum amount of hydrogen adsorbed on the MWCNT-graphite sample mixture was found as 0.75 and 0.54 wt.% by chemical treatments with KOH at 600 °C and NaOH at 700 °C, respectively whereas it was 0.01 wt.% for the original sample. The hydrogen sorption capacity was enhanced considerably by KOH treatments at 600 °C. © 2009 The Korean Society of Industrial and Engineering Chemistry 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

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

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

Adsorption equilibrium and breakthrough analysis for sulfur dioxide adsorption on silica gel

Kopaç, Türkan | Kocabaş, Sefa

Article | 2002 | Chemical Engineering and Processing41 ( 3 ) , pp.223 - 230

In this work, the adsorption equilibrium and adsorption rate of sulfur dioxide were investigated on silica gel. A packed bed adsorber 0.1 m in length and 0.0095 m in diameter was used for the adsorption experiments. The adsorption equilibrium experiments were carried out at 473 K constant temperature with an initial sulfur dioxide concentration in the range 430-3400 p.p.m. in nitrogen carrier gas. The experimental adsorption isotherms were compared with the Freundlich, Langmuir, and the linearized form of the Brunauer-Emmett-Teller and the Dubinin-Radushkevitch-Kaganer models by the nonlinear least-squares estimate method. The Freun . . .dlich model gave the best fit with a correlation coefficient greater than 0.98, suggesting a surface adsorption mechanism for sulfur dioxide adsorption on silica gel. The deactivation model was applied to the adsorption rate data. It was found that the adsorption rate data fitted well with the deactivation model. Observed adsorption rate constants and the first-order deactivation rate constants were obtained from the model. The nonlinear least-squares analysis technique was used to estimate the parameters appearing in the deactivation model. The breakthrough experiments were repeated at 1610 p.p.m. constant initial sulfur dioxide concentration in a temperature range of 323-473 K, and the effect of initial sulfur dioxide concentration and the effect of temperature were investigated on the model results. © 2002 Elsevier Science B.V. All rights reserved Daha fazlası Daha az

Sulfur dioxide adsorption isotherms and breakthrough analysis on molecular sieve 5A zeolite

Kopaç, Türkan | Kocabaş, Sefa

Article | 2003 | Chemical Engineering Communications190 ( 05.Aug ) , pp.1041 - 1054

In this study sulfur dioxide adsorption and rate were investigated on molecular sieve 5A zeolite in a packed bed system at 473 K. The experimental adsorption isotherms were compared with Langmuir, Freundlich, and Dubinin-Radushkevitch-Kaganer (DRK) adsorption isotherm models. The simple Langmuir and the Freundlich models provided a better description of sulfur dioxide sorption on molecular sieve 5A zeolite, so that a selective surface adsorption mechanism for adsorption of sulfur dioxide on molecular sieve 5A zeolite can he suggested. The breakthrough behavior for sulfur dioxide adsorption on molecular sieve 5A was also investigated . . . in this study. The experimental breakthrough curves were compared with deactivation models proposed by Orbey et al., and the recent models of Suyadal et al. and Yaşyerli et al. The deactivation models were found to give good agreement with the experimental results Daha fazlası Daha az

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