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Erdem, Sezer,Erdem, Beyhan,Oksuzoglu, Ramis Mustafa,Citak, Alime Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.5
Bifunctional Fe-SBA-15-$SO_3H$ mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, $N_2$-adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and $N_2$ sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-$SO_3H$. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-$SO_3H$, the acid sites substantially increased because of the self-separated acidity of the hydrolysis of $Fe^{3+}$ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.
Beyhan Erdem,Mustafa Cebe 한국화학공학회 2006 Korean Journal of Chemical Engineering Vol.23 No.6
of n-amyl alcohol with propionic acid catalyzed by macroporous (Amberlyst-15) and micro-When these catalysts were used as commercially available, Amberlyst-15 was observed to be the most effective catalystwith respect to rate constants, but after drying it became the less effective one. The reaction rate increased with increasein catalyst concentration and reaction temperature. Stirrer speed and different mesh sizes had virtually no effect on therate under the experimental conditions. The effect of divinylbenzene content was examined for the microporous resinDowex 50 W, and the results showed that the propionic acid conversion decreased as the divinylbenzene content wasincreased. The rate data were correlated with a second-order homogeneous reaction model. The apparent activationenergies, reaction enthalpies and entropy values were calculated for each catalyst. Reaction monitoring is simple and% 2.54.
Beyhan Erdem,Sezer Erdem,Nalan Tekin 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.7
Fe3O4-SiO2-NH2, Fe3O4-CTABSiO2-NH2 and Fe3O4-SiO2-CTABSiO2-NH2 magnetic adsorbents were successfully prepared and could be used effectively for the adsorption of Light Green from aqueous solutions. Unlike the first sample, mesoporous silica coatings were created using cetyltrimethylammoniumbromide micelles as molecular templates on superparamagnetic iron oxide in one sample, and on silica-coated iron oxide in the other sample to improve the adsorptive properties of the nanocomposites. The characterization by FT-IR, SEM/EDX, Zeta-potential, XRD, VSM, and N2-adsorption/desorption confirmed the production of mesoporous silica layer. Although coating processes with both silica and mesoporous silica layers led to a vaguely decrease in saturation magnetization of the Fe3O4- SiO2-CTABSiO2-NH2, the nanoparticles were protected with silica coatings for environment conditions and made more suitable for subsequent amino functionalization. The results determined from Batch adsorption experiments fitted to Langmuir isotherm model with maximum adsorption capacity (qmax) equal to 56.18, 196.08 and 227.27mg g1, for Fe3O4-SiO2-NH2, Fe3O4-CTABSiO2-NH2 and Fe3O4-SiO2-CTABSiO2-NH2, respectively, and it was seen from the kinetic results, the LG adsorption was identified by pseudo-second-order kinetics, revealing that LG adsorption process is homogeneous, monolayer and based on chemical interactions. According to the results, both silica and mesoporous silica coating strategy can play crucial role in improving the adsorptive properties of nanocomposites.
Sezer Erdem,Beyhan Erdem,Ramis Mustafa Öksüzo lu,Alime Ç tak 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.5
Bifunctional Fe-SBA-15-SO3H mesoporous materials with different Si/Fe molar ratios (3, 5, and 7) have been synthesized via a simple direct hydrothermal method and characterized by XRD, N2-adsorption/desorption, TG/DTG and FT-IR techniques, and used as solid acid catalysts in the esterification of lactic acid with methanol. XRD and N2 sorption characterizations show successful iron doping within the mesoporous channels of SBA-15-SO3H. The FT-IR and TG/DTG characterizations also reveal the presence of iron. With the incorporation of Fe ions into the SBA-15-SO3H, the acid sites substantially increased because of the selfseparated acidity of the hydrolysis of Fe3+ solutions. However, in the Si/Fe = 3 molar ratio, the catalytic conversion decreased which is caused by the reduced cooperation effect between the acid pairs due to the weakened hydrogen bonds and collapse of the pore structure. This further suggests that the mesoporous structure decreases with the decrease in Si/Fe ratio.
DEDE SAGSOZ, Yesim,YILMAZ, Alper Erdem,EKMEKYAPAR TORUN, Fatma,KOCADAGISTAN, Beyhan,KUL, Sinan The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.2
In this study, electrochemical treatment of urban wastewater with electrical conductivity of 1000 μS cm<sup>-1</sup> and chemical oxygen demand of 250 mg L<sup>-1</sup> was investigated using the variables of initial pH value, current density and flow rate. Electrocoagulation was used, in which aluminum and stainless steel were selected, as the electrochemical treatment process. The electrocoagulation process was operated in continuous mode. The data obtained in experimental studies show that the best COD removal efficiency occurred in experiments where the initial pH value was 6. The increase in current density from 5 A to 15 A decreased the removal efficiency from 79 to 67%. The increase in flow rate under constant current density also reduced the efficiency of removal as expected. In experiments in which current density and flow rate were examined together, the increase in flow rate allowed the application of higher current densities. This situation led to considerable reductions in energy consumption values, even if the COD removal efficiency did not significantly increase. The high COD removal obtained with the use of high flow rate and high current density indicates that the electrocoagulation process can be used for high flow rate municipal wastewater treatment.