In this study, a mild chemical method was developed to synthesize manganese oxide coated sepiolit... more In this study, a mild chemical method was developed to synthesize manganese oxide coated sepiolite from RS, Mn(NO 3) 2 and H 2 O 2 in an alkaline solution at room temperature. The samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), infrared (IR) and thermal analysis (TA). After heating up to 600 °C, the structure of the γ-MnO 2 phase gradually transformed into the Mn 2 O 3 phase. TA indicated the transformation of γ-MnO 2 into Mn 2 O 3 between 400 and 600 °C. IR spectra of manganese oxides showed signature bands between 400 and 650 cm − 1 due to Mn–O lattice vibrations. The thermal desorption of pyridine was followed by IR and TA techniques to estimate the acidity of the samples. Decomposition of formic acid over RS and MCS was studied by IR spectroscopy at 100–400 °C. Monodentate symmetric and asymmetric formates were observed after formic acid adsorption between 100 and 300 °C.
The difference in the basal spacing (8.79Å) and a higher mass loss (6.2%) in the temperature rang... more The difference in the basal spacing (8.79Å) and a higher mass loss (6.2%) in the temperature range of 200–750 • C of naproxen-bentonite (N-bentonite) comparing to that of Unye bentonite (UB) signified the existence of thermally stable organic species in the interlamellar space of the bentonite clay. The asym-metric OCO − stretching band (1607 cm −1) of N-bentonite became stronger in the temperature interval of 100–400 • C as a result of binding via the C O group of the ligand to exchangeable cation and/or water molecule whereas the OH bending peak of water (1633 cm −1) and the C C stretching vibration of aromatic ring (1531 cm −1) became weaker on thermal treatment. The effect of ionic strength on the des-orption of naproxen species and the related kinetic data revealed that the release mechanism at pH = 7.4 is unrestricted diffusion controlled and governed by the repulsive interactions between the bentonite surface and the negatively charged species. The pore structure characteristics of the bentonite samples corresponding to the surface area, pore volume and pore size were determined by using the conventional analysis of the nitrogen adsorption–desorption isotherms.
This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-bir... more This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-birnessite sample. Changes in the surface and structure were characterized using infrared spectroscopy, N2 gas adsorption–desorption, and thermal analysis techniques. The acid sites of H-birnessite were investigated by infrared and thermal analysis using pyridine as a molecular probe. Decomposition of formic acid started on H-birnessite at 120C and was complete at 400C. Infrared spectra revealed that the molecularly adsorbed formic acid species were transformed to a formate species, and the formate species were transformed to CO. The most stable adsorption structure for formic acid was found as a molecular monodentate configuration.
Adsorption Pb(II) This paper presents the synthesis, structural characterization and Pb(II) adsor... more Adsorption Pb(II) This paper presents the synthesis, structural characterization and Pb(II) adsorption behavior of K-birnessite and H-birnessite samples. Changes in the surfaces and structure of birnessite samples were characterized by means of infrared spectroscopy (IR), N 2 gas adsorption and thermal analysis (TG–DTA) techniques. Adsorption of Pb(II) by samples was investigated as a function of the initial Pb(II) concentration, solution pH, ionic strength, temperature and inorganic ligand (NO 3 − , Cl −). The Langmuir monolayer adsorption capacities of K-birnessite and H-birnessite samples in 0.1 M NaNO 3 solution at 298 K were estimated as 164.30 and 133.17 mg/g, respectively. Thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated for K-birnessite and H-birnessite to be −22.43 kJ/mol (at 298 K), 23.90 kJ/mol, 155 J/mol K, and −18.50 kJ/mol (at 298 K), 10.57 kJ/mol, 98 J/mol K, respectively.
In this study, new type of polysulfone (PSf) composite ultrafiltration membranes were prepared by... more In this study, new type of polysulfone (PSf) composite ultrafiltration membranes were prepared by blending PSf with poly[2,2 0-(m-phenylene)-5,5 0-dibenzimidazole] (PBI). The prepared membranes were characterized by water contact angle, SEM, FTIR, DSC, TG/DTG and cross-flow filtration techniques. We demonstrated that membrane characteristics such as porosity, hydrophilicity and thermal stability of PSf can be significantly enhanced with the incorporation of PBI. The composite membranes exhibited comparable bovine serum albumin (BSA) retention (69% vs. 36%) and water fluxes (355 vs. 228 L/m 2 h) against pristine PSf membranes.
Antibacterial effective, high performanced, novel ZnO embedded composite membranes were obtained ... more Antibacterial effective, high performanced, novel ZnO embedded composite membranes were obtained by blendig ZnO nanoparticles with polysulfone. IR, TG/DTG, XRD and SEM analysis were performed to characterize structure and morphology of ZnO nanoparticles and composite membranes. Contact angle, EWC, porosity and pore structure properties of composite membranes were investigated. Cross-flow filtration studies were performed to investigation of performances of prepared membranes. It was found from the cross section SEM images that ZnO nanoparticles dispersed homogenously up to additive amount of 2% and the membrane skin layer thicknesses increased in the presence of ZnO. Contact angle of pure PSf membranes were reduced from 70° to 55° after addition of 4% ZnO. Porosity of composite membrane contains 1% ZnO was higher about 22% than pure PSf membrane. BSA rejection ratio and PWF of 0.5% ZnO embedded composite membrane became 2.2 and 2.3 times higher than pure PSf membrane. It was determined from flux recovery ratios that ZnO additive increased the fouling resistance of composite membranes. Also, the bacterial killing ability of ZnO is well known and there are many researches related to this in the literature. Therefore, it is expected that prepared composite membranes will show antibacterial effect.
In this study, a mild chemical method was developed to synthesize manganese oxide coated sepiolit... more In this study, a mild chemical method was developed to synthesize manganese oxide coated sepiolite from RS, Mn(NO 3) 2 and H 2 O 2 in an alkaline solution at room temperature. The samples were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), infrared (IR) and thermal analysis (TA). After heating up to 600 °C, the structure of the γ-MnO 2 phase gradually transformed into the Mn 2 O 3 phase. TA indicated the transformation of γ-MnO 2 into Mn 2 O 3 between 400 and 600 °C. IR spectra of manganese oxides showed signature bands between 400 and 650 cm − 1 due to Mn–O lattice vibrations. The thermal desorption of pyridine was followed by IR and TA techniques to estimate the acidity of the samples. Decomposition of formic acid over RS and MCS was studied by IR spectroscopy at 100–400 °C. Monodentate symmetric and asymmetric formates were observed after formic acid adsorption between 100 and 300 °C.
The difference in the basal spacing (8.79Å) and a higher mass loss (6.2%) in the temperature rang... more The difference in the basal spacing (8.79Å) and a higher mass loss (6.2%) in the temperature range of 200–750 • C of naproxen-bentonite (N-bentonite) comparing to that of Unye bentonite (UB) signified the existence of thermally stable organic species in the interlamellar space of the bentonite clay. The asym-metric OCO − stretching band (1607 cm −1) of N-bentonite became stronger in the temperature interval of 100–400 • C as a result of binding via the C O group of the ligand to exchangeable cation and/or water molecule whereas the OH bending peak of water (1633 cm −1) and the C C stretching vibration of aromatic ring (1531 cm −1) became weaker on thermal treatment. The effect of ionic strength on the des-orption of naproxen species and the related kinetic data revealed that the release mechanism at pH = 7.4 is unrestricted diffusion controlled and governed by the repulsive interactions between the bentonite surface and the negatively charged species. The pore structure characteristics of the bentonite samples corresponding to the surface area, pore volume and pore size were determined by using the conventional analysis of the nitrogen adsorption–desorption isotherms.
This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-bir... more This paper presents the adsorption and thermal decomposition mechanism of formic acid on an H-birnessite sample. Changes in the surface and structure were characterized using infrared spectroscopy, N2 gas adsorption–desorption, and thermal analysis techniques. The acid sites of H-birnessite were investigated by infrared and thermal analysis using pyridine as a molecular probe. Decomposition of formic acid started on H-birnessite at 120C and was complete at 400C. Infrared spectra revealed that the molecularly adsorbed formic acid species were transformed to a formate species, and the formate species were transformed to CO. The most stable adsorption structure for formic acid was found as a molecular monodentate configuration.
Adsorption Pb(II) This paper presents the synthesis, structural characterization and Pb(II) adsor... more Adsorption Pb(II) This paper presents the synthesis, structural characterization and Pb(II) adsorption behavior of K-birnessite and H-birnessite samples. Changes in the surfaces and structure of birnessite samples were characterized by means of infrared spectroscopy (IR), N 2 gas adsorption and thermal analysis (TG–DTA) techniques. Adsorption of Pb(II) by samples was investigated as a function of the initial Pb(II) concentration, solution pH, ionic strength, temperature and inorganic ligand (NO 3 − , Cl −). The Langmuir monolayer adsorption capacities of K-birnessite and H-birnessite samples in 0.1 M NaNO 3 solution at 298 K were estimated as 164.30 and 133.17 mg/g, respectively. Thermodynamic parameters such as change in free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were evaluated for K-birnessite and H-birnessite to be −22.43 kJ/mol (at 298 K), 23.90 kJ/mol, 155 J/mol K, and −18.50 kJ/mol (at 298 K), 10.57 kJ/mol, 98 J/mol K, respectively.
In this study, new type of polysulfone (PSf) composite ultrafiltration membranes were prepared by... more In this study, new type of polysulfone (PSf) composite ultrafiltration membranes were prepared by blending PSf with poly[2,2 0-(m-phenylene)-5,5 0-dibenzimidazole] (PBI). The prepared membranes were characterized by water contact angle, SEM, FTIR, DSC, TG/DTG and cross-flow filtration techniques. We demonstrated that membrane characteristics such as porosity, hydrophilicity and thermal stability of PSf can be significantly enhanced with the incorporation of PBI. The composite membranes exhibited comparable bovine serum albumin (BSA) retention (69% vs. 36%) and water fluxes (355 vs. 228 L/m 2 h) against pristine PSf membranes.
Antibacterial effective, high performanced, novel ZnO embedded composite membranes were obtained ... more Antibacterial effective, high performanced, novel ZnO embedded composite membranes were obtained by blendig ZnO nanoparticles with polysulfone. IR, TG/DTG, XRD and SEM analysis were performed to characterize structure and morphology of ZnO nanoparticles and composite membranes. Contact angle, EWC, porosity and pore structure properties of composite membranes were investigated. Cross-flow filtration studies were performed to investigation of performances of prepared membranes. It was found from the cross section SEM images that ZnO nanoparticles dispersed homogenously up to additive amount of 2% and the membrane skin layer thicknesses increased in the presence of ZnO. Contact angle of pure PSf membranes were reduced from 70° to 55° after addition of 4% ZnO. Porosity of composite membrane contains 1% ZnO was higher about 22% than pure PSf membrane. BSA rejection ratio and PWF of 0.5% ZnO embedded composite membrane became 2.2 and 2.3 times higher than pure PSf membrane. It was determined from flux recovery ratios that ZnO additive increased the fouling resistance of composite membranes. Also, the bacterial killing ability of ZnO is well known and there are many researches related to this in the literature. Therefore, it is expected that prepared composite membranes will show antibacterial effect.
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