Browsing by Author "Savran, A."

Now showing 1 - 6 of 6

Adsorption of Pb (Ii) Ions From Aqueous Solutions Onto Paliurus Spina-Christimill. Frutis and Seeds
(Parlar Scientific Publications, 2020) Savran, A.; Kul, A.R.; Kubilay, S.; Selcuk, N.C.
In this study, Paliurus spina-christi Mill, frutis and seeds (PSCFS) was used as an adsorbent for Pb(II) ions removal from water solutions. The effect of various experimental parameters was investigated using a batch adsorption technique. In the adsorption experimental, temperature, contact time and concentrations effects upon Pb (II) ions on PSCFS were thoroughly examined at pH 5.2. Results show that a temperature value of 45 °C is favorable for the adsorption of Pb (II) ions. The isothermal data could be well described by the Freundlich equation. The kinetic data fit well with the pseudo-second-order kinetic model. The adsorption capacity of PSCFS was found to be 14.97°1 mg g- 1 at 45 °C according to pseudo-second-order model data. Thermodynamic parameters such as activation energy (Ea) and change in the free energy (AG°), the enthalpy (AH°), and the entropy (AS°) were also evaluated. The all adsorption process was endothermic and spontaneous. The results indicate that PSCFS could be employed as low-cost materials for removal from water of Pb (II) ions. © by PSP.
Determination of the Surface Properties of Untreated and Chemically Treated Kaolinites by Inverse Gas Chromatography
(Maik Nauka/interperiodica/springer, 2006) Kubilay, S.; Guerkan, R.; Savran, A.; Yalcinkaya, Z.
Inverse gas chromatography is used to study the surface properties of the untreated and chemically treated kaolinite samples. Changes in the enthalpy of adsorption for a variety of probes and in the surface energy of clays are measured and the effect of modification of the natural clay after chemical treatment with Na2CO3 is determined. The surface energy of the natural clay increased by the modification due to an increase in the surface area. It can be concluded that the dispersive component of surface free energy, gamma(d)(s), decreases with temperature in the 200-275 degrees C temperature range for both samples. Temperature coefficients of gamma(d)(s) for untreated and modified kaolinites are -0.1185 and -0.3966 mJ/(m(2)degrees C) with the correlation coefficients (R-2) of 0.8479 and 0.965, respectively. From the retention data for polar probes at infinite dilution, information on the accessibility of surface sites to the probes and on the acid-base character of the surface is obtained. The specific free energy of adsorption, the specific enthalpy of adsorption (Delta H-sp), and the specific entropy of adsorption of polar probes on initial and modified kaolinites are determined. The Delta H-sp values correlated with the donor numbers and modified acceptor numbers of the probes to quantify the acidity (K-A) and basicity (K-D) parameters of clay surfaces. The values of K-A and K-D for initial and modified kaolinites are determined to be 0.1202 and 0.2803; 0.0130 and 0.0408 with the correlation coefficients of -0.9805 and -0.9782, respectively. The unmodified clay sample indicated a more acidic character, while the modified clay sample conferred a largely basic character. Consequently, the predominant surface basicity of the modified kaolinite agrees with expectation, hearing in mind the treatment with Na2CO3, taking into consideration that such a modification contributes to a decrease in the hydrophilicity of the surface and also results in the surface showing only weak Lewis acidity.
Dissolution Kinetics of Thermally Dehydrated Colemanite in Perchloric Acid Solutions
(Asian Journal of Chemistry, 2008) Kubilay, S.; Yalcinkaya, Z.; Alkan, S.; Savran, A.
In this study, the dissolution of thermally dehydrated colemanite in aqueous perchloric acid solutions was investigated in a batch reactor employing the parameters of solid to liquid ratio particle size, temperature and acid concentration. It was found that the dissolution rate increased with increasing temperature and acid concentration, decreasing particle size and solid to liquid ratio. No important effect of stirring speed was observed, The dissolution kinetics of colemanite was examined according to heterogeneous and homogeneous reaction models and it was found that the dissolution rate was controlled by heterogeneous chemical reaction. The activation energy of the process was determined to be 41.07 kJ mol(-1). The experimental data were tested by graphical and statistical methods and it was found that the following model best fit the experimental data 1 - (1 -X)(1/3) = 7.56 x 10(5) (Rp)-0.1076 x (C-Lambda)0.4629 x (S/L) - 0.2525 x e(-4938) x t.
Erratum: Effects of Some Drugs on Enzyme Activity of Catalase From Bovine Liver (Asian Journal of Chemistry (2006) 18, 1 (601-607))
(Chemical Publishing Co., 2006) Alkan, S.; Savran, A.; Demir, H.; Ceylan, H.
Immobilization of Catalase Via Adsorption Into Natural and Modified Active Carbon Obtained From Walnut in Various Methods
(Academic Journals, 2009) Alkan, S.; Gur, A.; Ertan, M.; Savran, A.; Gur, T.; Genel, Y.
In the present work, the immobilization of catalase into natural active carbon and active carbon modified by hydrochloric acid was carried out. In the experimental section, the effects of pH, ionic strength and reaction temperature were chosen as parameters, with experiments performed in batch system. For the optimization of immobilization procedure, values of kinetic parameters were evaluated. It was observed that storage and operational stabilities of the enzyme increased with immobilization. The results obtained from experiments showed that active carbon is a valuable support for the adsorption of enzymes.
Removal of Cu(Ii), Zn(Ii) and Co(Ii) Ions From Aqueous Solutions by Adsorption Onto Natural Bentonite
(Springer, 2007) Kubilay, S.; Gurkan, R.; Savran, A.; Sahan, T.
In this study, the removal of Cu(II), Zn(II) and Co(II) ions from aqueous solutions using the adsorption process onto natural bentonite has been investigated as a function of initial metal concentration, pH and temperature. In order to find out the effect of temperature on adsorption, the experiments were conducted at 20, 50, 75 and 90 degrees C. For all the metal cations studied, the maximum adsorption was observed at 20 degrees C. The batch method has been employed using initial metal concentrations in solution ranging from 15 to 70 mL(-1) at pH 3.0, 5.0, 7.0 and 9.0. A flame atomic absorption spectrometer was used for measuring the heavy metal concentrations before and after adsorption. The percentage adsorption and distribution coefficients (K-d) were determined for the adsorption system as a function of adsorbate concentration. In the ion exchange evaluation part of the study, it is determined that in every concentration range, adsorption ratios of bentonitic clay-heavy metal cations match to Langmuir, Freundlich and Dubinin-Kaganer-Radushkevich (DKR) adsorption isotherm data, adding to that every cation exchange capacity of metals has been calculated. It is shown that the bentonite is sensitive to pH changes, so that the amounts of heavy metal cations adsorbed increase as pH increase in adsorbent-adsorbate system. It is evident that the adsorption phenomena depend on the surface charge density of adsorbent and hydrated ion diameter depending upon the solution pH. According to the adsorption equilibrium studies, the selectivity order can be given as Zn2+ > Cu2+ > Co2+. These results show that bentonitic clay hold great potential to remove the relevant heavy metal cations from industrial wastewater. Also, from the results of the thermodynamic analysis, standard free energy Delta G(0), standard enthalpy Delta H-0 and standard entropy Delta S-0 of the absorption process were calculated.