Browsing by Author "Sogut, Eda Gokirmak"

Now showing 1 - 13 of 13

Adsorption of Uranium (Vi) From Aqueous Solutions Using Boron Nitride/Polyindole Composite Adsorbent
(Wiley, 2024) Emre, Deniz; Zorer, Ozlem Selcuk; Bilici, Ali; Budak, Erhan; Yilmaz, Selehattin; Kilic, Necla Caliskan; Sogut, Eda Gokirmak
Turbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT-IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C-0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0-5.5, T = 307 K, t = 10 min, C-0 = 18 mg L-1. These experimental results are evaluated using Freundlich, Redlich-Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (q(m)) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g(-1). The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo-second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4-40 mg L-1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U-O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.
Adsorption of Zinc(Ii) on Diatomite and Manganese-Oxide Diatomite: a Kinetic and Equilibrium Study
(Elsevier, 2011) Caliskan, Necla; Kul, Ali Riza; Alkan, Salih; Sogut, Eda Gokirmak; Alacabey, Ihsan
The removal of Zn(II) ions from aqueous solution was studied using natural and MnO2 modified diatomite samples at different temperatures. The linear Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption equations were applied to describe the equilibrium isotherms. From the D-R model, the mean adsorption energy was calculated as >8 kJ mol(-1), indicating that the adsorption of Zn(II) onto diatomite and Mn-diatomite was physically carried out. In addition, the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to determine the kinetic data. The experimental data were well fitted by the pseudo-second-order kinetic model. Thermodynamic parameters such as the enthalpy (Delta H-0), Gibbs' free energy (Delta G(0)) and entropy (Delta S-0) were calculated for natural and MnO2 modified diatomite. These values showed that the adsorption of Zn(II) ions onto diatomite samples was controlled by a physical mechanism and occurred spontaneously. (C) 2011 Elsevier B.V. All rights reserved.
Effect of Chemical and Thermal Treatment Priority on Physicochemical Properties and Removal of Crystal Violet Dye From Aqueous Solution
(Wiley-v C H verlag Gmbh, 2022) Sogut, Eda Gokirmak
The release of pollutants, especially dyes, has been a significant concern as it affects the stability of ecosystems due to poor implementation of waste protocols. In this study, the diatomite samples were characterized by pH(pzc), ICP, pore size distribution, XRD, TG-DTA, BET, SEM and FTIR (before-after). The adsorption properties of a cationically charged dye, crystal violet (CV), on the diatomite samples were investigated by varying the adsorption parameters with the aim of evaluating the adsorption mechanism. Nonlinear Langmuir, Freundlich, Dubinin-Radushkevich and Redlich-Peterson isotherm models, pseudo-first and pseudo-second order kinetic models, intraparticle diffusion and Boyd models were evaluated. The adsorption mechanism was explained by the Langmuir isotherm model and the maximum adsorption capacities for CV (at pH 7.0) of D-HCl, D800 degrees C+HCl and DHCl+800 degrees C were 5.07 mg g(-1) and 4.93 mg g(-1) and 65.78. mg g(-1) at 298 K, respectively. It was also shown that the CV adsorption was reasonable according to the second-order kinetic model (R-2=1). Adsorption occurred via two mechanisms: hydrophobic interactions and the combination of surface hydrogen bonding between the hydroxyl groups on the diatomite surface and the nitrogen atoms of the CV. The results indicated that using DHCl+800 degrees C would provide a simple, energy-saving, and cost-effective approach to removing cationic dyes from an aqueous solution.
The Effect of Mercapto-Functionalization of Thermo-Acid Activated Diatomite for Dye Removal From Aqueous Solutions
(Taylor & Francis Ltd, 2022) Sogut, Eda Gokirmak; Kilic, Necla Caliskan
For the adsorption of malachite green (MG), 'purified by thermo-acid (HCl) diatomite' (D-TA) and its derivative '3-mercaptopropyltrimethoxysilane functionalised diatomite' (DTA-MTMS) were prepared as adsorbent and the effects of thermo-acid activation and surface functional groups on adsorption were investigated. Many acids dissolve certain substances in diatomite and change their chemical composition. Thermo-acid treatment and silane-modified diatomite fractions were characterised byBrunauer-Emmett-Teller (BET), scanning electron microscope (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal analysis (TG-DTA). The effects of contact time, solution pH, temperature and initial dye concentration on adsorption were investigated. Equilibrium isotherms are defined using nonlinear Langmuir, Freundlich, Dubinin - Radushkevich (D - R) and Sips adsorption isotherm equations. Isotherm data for both adsorbents are best fitted on the Freundlich and Sips model. The q(max) values determined from the Sips model are 18.8415 mgg(-1) and 21.4713 mgg(-1) for D-TA and DTA-MTMS, respectively. It was determined that DTA-MTMS performed better than D-TA for MG adsorption. The results showed that MG adsorption was compatible with the pseudo-second-order (PSO) kinetic model. From the adsorption energy value (E < 8 kJ mol(-1)), it was confirmed that physical adsorption was dominant in the adsorption process. The nature of the sorption process is exothermic and spontaneous (due to negative values Delta H degrees and Delta G degrees). The results of the study showed that prepared D-TA and synthesised DTA-MTMS can be considered as an economical and promising adsorbent in removing organic dyes from wastewater.
Enhancement of Adsorption Capacity of Reduced Graphene Oxide by Sulfonic Acid Functionalization: Malachite Green and Zn (Ii) Uptake
(Elsevier Science Sa, 2020) Sogut, Eda Gokirmak; Karatas, Yasar; Gulcan, Mehmet; Kilic, Necla Caliskan
Graphene oxide (GO) was synthesized according to the Hummers' method developed to remove some impurities such as malachite green dye and Zn (II) metal ion from aqueous solutions. However, due to the problem of dispersion in water, graphene oxide surface is generally functionalized or composites are prepared with different materials. For this reason, the produced graphene oxide is functionalized with sulfanilic acid to obtain reduced sulfonated graphene oxide (rGO-SO3H). For the characterization of materials, DR/UV-vis, Raman, FT-IR, SEM and SEM-EDX mapping techniques were used. Also, reduced graphene oxide (rGO) was evaluated as a comparative example in adsorption. Effect of parameters such as pH, initial concentration and temperature on the removal of metal ions and dye was studied. Equilibrium was achieved in 90 min. The highest percentage removal of rGO and rSGO was observed at pH = 7. Equilibrium isotherms are defined using nonlinear Langmuir, Freundlich, Dubinin - Radushkevich (D - R) and Sips adsorption isotherm equations. Maximum adsorption capacities were determined as 588.23 mg g 1 and 1111.11 mg g(-1) for malachite green, 166.66 mg g(-1) and 322.58 mg g(-1) for Zn (II), respectively for rGO and rGO-SO3H. Kinetic experimental results fit well with the pseudo-second order model for both dye and metal ion; coefficients of determination were close to 1. Thermodynamic studies showed that the adsorption was spontaneous and the adsorption processes were controlled by a physical mechanism.
High-Efficiency Removal of Cationic Dye and Heavy Metal Ions From Aqueous Solution Using Amino-Functionalized Graphene Oxide, Adsorption Isotherms, Kinetics Studies, and Mechanism
(Tubitak Scientific & Technological Research Council Turkey, 2022) Celebi, Metin; Sogut, Eda Gokirmak
GO-NH2 (amino functionalized graphene oxide) was synthesized by grafting (3-aminopropyl) triethoxysilane onto the surface GO (graphene oxide). The GO-NH2 with a higher surface area and many active sites was characterized and its effectiveness in removing Rhod B dye and Ni(II) ions from wastewater by adsorption was observed. The effects of pH, time, and strange ions on the adsorption efficiency were investigated. The equilibrium isotherm data confirmed that it fits the Langmuir and Freundlich isotherm models. GO and GO-NH2 exhibited high adsorption capacity (QM); 2500 (mg L-1) and 3333 (mg L-1) for Rhod B dye, and 312.5 (mg L-1), and 714.28 (mg L-1) for Ni(II) ions, respectively. The kinetics of adsorption was studied using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and the Boyd model. It was found that the adsorption followed pseudo-second-order and film diffusion model are effective in this adsorption process. Adsorption mechanisms have been attributed to possible electrostatic attractions, hydrogen bonding, and interactions. In summary, the experimental results showed the synthesized GO and GO-NH2 would be promising adsorbents to remove aqueous solutions contaminated with Rhod B dye and Ni(II) ions.
Isotherm and Kinetic Studies of Pb(Ii) Adsorption on Raw and Modified Diatomite by Using Non-Linear Regression Method
(Parlar Scientific Publications (p S P), 2017) Sogut, Eda Gokirmak; Caliskan, Necla
This study presents the evaluation of the original diatomite (D-O) and manganese oxide modified (D-mn) diatomite used as adsorbents for Pb (II) removal from aqueous solution. The experimental data were fitted to the non-linear two parameter equation of Langmuir, Freundlich, Dubinin-Radushkevich, and non-linear three parameter equation of Redlich-Peterson, Sips and Toth Isotherms. The correlation coefficient (R-2), standard error (S.E) and Chi-square (x(2)) values were used to select the best theoretical isotherm. Adsorption mechanism of Pb(H) ion onto the D-O was explained by heterogeneous adsorption model while homogenous adsorption model was used to explain the adsorption on D-mn. Also, both adsorbents were observed to comply better with the three-parameter isotherms. Pseudo first-order, pseudo second-order, Elovich and intraparticle diffusion equations were used to describe the adsorption rate of Pb(II). The experimental data were well fitted by the pseudo second-order kinetic model. Thermodynamic parameters such as free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees) showed spontaneous and endothermic in nature of adsorption for both of adsorbents.
Methylene Blue Adsorption From Aqueous Solution by Functionalized Perlites: an Experimental and Computational Chemistry Study
(desalination Publ, 2021) Sogut, Eda Gokirmak; Ergan, Erdem; Kilic, Necla Caliskan; Donmez, Hakan; Akbas, Esvet
In this study, 3-aminopropyltrimethoxy-silane (3-APTMS) and 3-mercaptopropyltrimethoxy-silane (3-MPTMS) were used to functionalize perlite in order to increase the adsorption capacity of methylene blue (MB). These materials were characterized by X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermal (thermogravimetry/ differential thermal analysis) analyzes. The performance of perlite and functionalized derivatives was tested by adsorption of MB in a batch system under a variable pH (2-11) and initial MB concentration (10-60 mg L-1). Nonlinear and linear Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Sips adsorption equations were applied to define equilibrium isotherms. The maximum dye sorption was found to be at a pH of 11.0 (96.44% for P-A, 96.51% for P-APTMS, and 96.73% for P-MPTMS). The adsorption capacity for the dye was found to be 4.9445, 5.2014, and 5.3112 mg g(-1) for P-A, P-APTMS, and P-MPTMS, respectively, at 298 K. The adsorption kinetics was best described by the pseudo-second-order model. The obtained results confirm that amino and mercapto functional groups have positive effects on the adsorption of methylene blue by the adsorbents used in this work. Quantum chemical analysis supported better adsorption of methylene blue dye on amine and mercapto-functionalized perlite surfaces than the unmodified surface and the most suitable site for MB adsorption was suggested by Fukui function analysis.
Porous Graphitic Carbon Nitride Nanosheets Coated With Polyfluorene for Removal of Malachite Green and Methylene Blue Dyes and Cu (Ii) Ions
(Elsevier Science Sa, 2022) Sogut, Eda Gokirmak; Emre, Deniz; Bilici, Ali; Kilic, Necla Caliskan; Yilmaz, Selehattin
Dyes and heavy metal ions are of great interest for environmental studies as they are common pollutants in industrial applications. Therefore, development of innovative adsorbents has received tremendous interest in wastewater treatment studies. In this study, a new hybrid adsorbent (g-C3N4/AFP) was prepared by modifying porous graphitic carbon nitride surface (g-C3N4) with 2-amino fluorene polymer (AFP) and investigated its adsorptive behaviour for removal of representative dyes and heavy metal from aqueous solution. Experimental data obtained from batch tests were analysed using two parameters (Freundlich, Langmuir and Dubi-nin-Radushkevich) and three parameters (Sips) isotherm models. Langmuir isotherms were the best model to describe the experimental results of Methylene blue (MB) and Malachite green (MG) dye adsorptions, while Freundlich isotherms were the best for Cu (II) ions. Sips isotherm model was found to have the highest regression coefficient (>= 0.99) among the two-parameters isotherms studied. The maximum adsorption capacities of g-C3N4 and g-C3N4/AFP were found to be 226.88 and 327.83 for MG, 85.73 and 221.85 for MB and 184.51 and 452.19 mg g(-1) for Cu (II), respectively. This increase in adsorption capacity can be explained by the improved textural properties of the new hybrid adsorbent and the presence of multiple functional groups in its structure. A possible adsorption mechanism was suggested using FTIR and pH(pzc) data.
Removal of Cu(Ii) and Cd(Ii) Ions From Aqueous Solutions Using Local Raw Material as Adsorbent: a Study in Binary Systems
(desalination Publ, 2017) Caliskan, Necla; Sogut, Eda Gokirmak; Savran, Ali; Kul, Ali Riza; Kubilay, Senol
The purpose of this study is to examine the interaction of Cu(II) and Cd(II) ions in solution with the local raw clayey material of Tilkitepe located in the eastern shore of Lake Van in East Anatolia (Turkey). This material was used as an adsorbent without any chemical or physical treatment and was characterized by X-ray fluorescence, X-ray diffraction, scanning electron microscope, Fourier transform infrared and differential thermal analysis-thermogravimetric analyses. Langmuir, Freundlich, Dubinin-Kaganer-Radushkevich, Temkin and Harkins-Jura non-linear adsorption isotherm models were applied to the experimentally obtained adsorption data and the isotherm constants were calculated. The highest R-2 values for adsorption of both ions in the binary system were obtained by applying the experimental data to the Freundlich isotherm model. In binary system, the experimental adsorption capacities for Cu(II) and Cd(II) ions obtained by kinetic data were 52.631 and 44..843 mg g(-1) at 600 mg L-1 initial metal ion concentrations, respectively In the competitive adsorption, the affinity of Cu(II) toward the adsorbent was much higher than that of the Cd(II). Adsorption kinetics was evaluated using the pseudo-first-order, pseudo-second-order, intraparticle diffusion, Avrami and mass transfer kinetic models. The experimental data proved a closer fit to the pseudo-second-order model. Thermodynamic parameters such as enthalpy (Delta H degrees), Gibbs free energy (Delta G degrees) and entropy (Delta S degrees) were calculated using adsorption isotherms obtained at different temperatures. The results show that the adsorption is spontaneous and controlled by a physical mechanism.
Removal of Lead, Copper and Cadmium Ions From Aqueous Solution Using Raw and Thermally Modified Diatomite
(desalination Publ, 2017) Sogut, Eda Gokirmak; Caliskan, Necla
In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite. The prepared calcined diatomite samples were characterized by the X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. The raw and thermally modified diatomite at 500 degrees C was tested for the adsorption of Pb(II), Cu(II) and Cd(II) from aqueous solutions. Adsorption experiments were performed under batch process, using metal ions initial concentration, contact time and temperature as variables. The linear Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption equations were applied to describe the equilibrium isotherms. Equilibrium studies showed that thermally modified diatomite has a higher removal capacity for Pb(II), Cu(II) and Cd(II) from water than untreated diatomite. The kinetic data were evaluated using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic equations. The experimental data proved a closer fit to the pseudo-second-order model. Thermodynamic parameters such as the enthalpy (Delta H-0), Gibbs' free energy (Delta G(0)) and entropy (Delta S-0) were calculated for raw and thermally modified diatomite. These values showed that the adsorption of Pb(II), Cu(II) and Cd(II) ions onto diatomite samples was controlled by a physical mechanism and occurred spontaneously.
Removal of Thioflavin T and Co(Ii) Ions From Aqueous Solution Using Go and Go- Edta; Adsorption Parameters and Mechanism
(Gazi Univ, Fac Engineering Architecture, 2024) Sogut, Eda Gokirmak; Celebi, Metin
Dyes and heavy metals are typical pollutants causing environmental problems. In this study, the efficiency of GO and GO-EDTA used as adsorbents for Thioflavin T (TFT) and Co(II) metal ion removal from aqueous solution under optimum conditions was investigated. GO-EDTA was characterized by DR-UV/VIS, Raman spectra, FTIR and zero charge points (pHpzc) were determined using pH drift method. The maximum adsorption capacities (qM) of the adsorption process according to the Langmuir isotherm model, one of the isotherm models, refer to GO or GO-EDTA; It is 389.3178 mg g(-1) and 1009.5300 mg g(-1) for TFT dye, 736.9153 mg g(-1) and 1304.3525 mg g(-1) for Co(II) ion (pH=7, t=150 min, 298 K). The kinetic data fit the pseudo-second order model quite well. In the desorption graph, TFT dye desorption was observed to be quite efficient, while the reason for the decrease in the desorption of Co(II) ion was considered to be the strong bond formed as a result of ion exchange at the-COONa end in the EDTA structure. It was supposed that pi-pi interactions with benzene rings in GO and GO-EDTA structure, hydrogen bonding with functional groups on the structure and electrostatic interactions as a result of ion exchange at the carboxylic acid ends were generally effective in the adsorption mechanism. In conclusion, it was shown that GO and GO-EDTA nanomaterials can be effectively used as advanced adsorbents instead of traditional adsorbents for the removal of organic and inorganic pollutants from aqueous solution.
Single-Walled Carbon Nanotube Supported Pt-Ru Bimetallic Superb Nanocatalyst for the Hydrogen Generation From the Methanolysis of Methylamine-Borane at Mild Conditions
(Nature Portfolio, 2019) Sogut, Eda Gokirmak; Acidereli, Hilal; Kuyuldar, Esra; Karatas, Yasar; Gulcan, Mehmet; Sen, Fatih
Several metal nanoparticle based catalysts have been synthesized for catalyzing the hydrogen production process by hydrolysis of methylamine-borane (MeAB). However, there was only one study that catalyzes the producing of hydrogen via the methanolysis of MeAB, and it was carried out by our research group. For this reason, in this work, a new catalyst system entitled by single-walled carbon nanotube (SWCNT) supported bimetallic platinum-ruthenium nanoparticles were developed and called as PtRu@SWCNT. These NPs were characterized by several techniques (XRD, XPS, Raman, and TEM), and they were performed for the methanolysis of MeAB with high catalytic activity. The prepared PtRu@SWCNT NPs were also tested in the methanolysis of MeAB at different parameters including different temperatures, catalyst and substrate concentrations, and reusability performance. Experimental results revealed that the new PtRu@SWCNT NPs had excellent catalytic activity and reusability for removing of hydrogen from the methanolysis of MeAB at ambient conditions. According to the obtained data, the turnover frequency is 136.25 mole H-2/mole PtRu x min, and the activation energy (Ea) is 17.29 kJ/mole. More than 99% of conversion was observed at room temperature.