Browsing by Author "Aldemir, A."

Now showing 1 - 8 of 8

Adsorption of Acid Blue 25 on Peach Seed Powder: Isotherm, Kinetic and Thermodynamic Studies
(Yildiz Technical University, 2019) Kul, A.R.; Aldemir, A.; Elik, H.
In the present study peach seed powder (PSP) was used as an adsorbent to remove Acid Blue 25 (AB25) a common basic dye, from aqueous solution. The adsorption experiments were carried out in a batch system and the effects of initial concentration, interaction time and temperature were investigated. The Langmuir, Freundlich and Temkin adsorption isotherms were used to model the equilibrium data. The kinetic parameters were determined by the pseudo first order (PFO), pseudo second order (PSO) and intra-particle diffusion (IPD) models. According to the results, the Freundlich isotherm model is a more convenient option compared with the Langmuir and Temkin models. The Freundlich model coefficients increased as the temperature increased, which shows that the adsorption process becomes more favorable with higher temperature. The experimental and calculated qe values close to one another indicated that this process fits the PSO kinetic model with higher R2 values than the other two models. Kinetic constants become closer to both the temperatures and initial concentrations and qe values increases with the increasing concentration of AB25. The initial dye concentration increased from 25 to 150 mg L-1, while the dye adsorption capacity onto PSP increased from 4.80 to 39.01 mg g-1, from 5.57 to 44.27 mg g-1 and from 6.80 to 49.22 mg g-1 for 298, 308 and 323 K, respectively. The monolayer adsorption capacity (qm) of PSP was determined to be 56.18, 64.94, 95.24 mg g-1 for 298, 308 and 323 K, respectively. Thermodynamic parameters for free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of the separation process were determined as -1737,1 J mol-1, 14.776 kJ mol-1 and 55,413 J mol-1, respectively. The negative values of ΔGo showed that this separation process was endothermic and natural. The results of the present study demonstrated that PSP can be used as an alternative material in dye removal. © 2023 Bulletin of Monetary Economics and Banking.
Adsorption of Basic Blue 41 Using Juniperus Excelsa: Isotherm, Kinetics and Thermodynamics Studies
(Yildiz Technical University, 2019) Kul, A.R.; Aldemir, A.; Alkan, S.; Elik, H.; Caliskan, M.
In this study Juniperus excelsa shavings powder (JESP) was utilized as an adsorbent for the removal of Basic Blue 41 (BB 41) which is one of the common basic dyes, from aqueous solution. The adsorption experiments were carried out in a batch system and effects of initial concentration of dye, interaction time and temperature were investigated. Langmuir, Freundlich and Temkin adsorption isotherms were used to model equilibrium data. According to the results, Freundlich isotherm model becomes more convenient option compared with Langmuir and Temkin models. Freundlich model coefficients are raise as the temperature rises, showing that the adsorption process becomes favorable higher temperature. The kinetic parameters were determined by pseudo first order (PFO), pseudo second order (PSO) and intra-particle diffusion (IPD) models. Results indicated that experimental and calculated qe values are matched to each other. Thus the process fits PSO kinetic model with higher R2 values than other two models. Kinetic constants become closer to both temperatures and initial concentrations and qe values are increases with increasing concentration of BB 41. Initial dye concentration elevates from 25 to 100 mg L-1, dye adsorption capacity onto JESP from 3.06 to 16.53 mg g-1, respectively. Thermodynamic parameters for instance free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) were assessed. Enthalpy and entropy of this separation process are determined from 3081.91 J mol-1 and 12.33 kJ mol-1, respectively. The negative values of ΔG° showed that this separation process was endothermic and natural. The research results demonstrate that JESP may be a substitute than pricey adsorbents for dye removal. © 2019 Yildiz Technical University. All rights reserved.
Comprehensive Investigation of Basic Red 46 Removal by Pinecone Adsorbent: Experimental, Isotherm, Kinetic and Thermodynamic Studies
(Springer, 2023) Aldemir, A.; Turan, A.; Kul, A. R.; Koyuncu, H.
In this study, pinecone sawdust (PCS) performance was investigated for Basic Red 46 (BR 46) dye adsorption from aqueous solutions. The physicochemical and morphological characterization of PCS before and after BR 46 adsorption were evaluated with the help of Fourier transform infrared spectra, X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectroscopy analysis. Effects of initial dye concentration, temperature and contact time were determined for BR 46 adsorption. Seventeen equilibrium isotherm models and eight kinetic models were compared at 298 K, 308 K and 318 K temperatures for five different concentrations which varied from 20 to 60 mg/L. The obtained adsorption data best-fit the Freundlich model among all the applied isotherm models, and the maximum adsorption capacity (q(m)) was calculated as 129.87 mg/g at 298 K. The pseudo-second-order model was the best choice to describe the adsorption behavior among all the applied kinetic models. The removal percentage of BR 46 dye with PCS was 74.52% at 318 K for 60 mg/L concentration. The negative free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (Delta S degrees) values of adsorption were calculated as - 2837 kJ/mol, 18,898 kJ/mol and 68.51 J/mol K, respectively. This adsorption process was spontaneous and favorable, coinciding with the negative free energy. The activation energy (E-A) value of this process was determined with the Arrhenius equation as 19.92 kJ/mol. The reliability of all results was analyzed statistically and evaluated with correlation coefficient (R-2), sum of squares, sum of the square of error and mean square of error values. As a result of this study, PCS can be used effectively for BR 46 dye removal. [GRAPHICS] .
Damage From Two Consecutive Earthquakes at City of Van (Turkey)
(Earthquake Engineering Research Institute, 2014) Aldemir, A.; Erdil, B.; Demirel, I.O.; Yakut, A.; Binici, B.
One of the most devastating natural events is, definitely, earthquake. The energy released from earthquakes test performance of a large building stock. Distressingly, some buildings fail to possess enough strength and/or ductility during these events, causing loss of lives and property. Therefore, the observations from past natural events play an important role in decreasing the losses during future natural disasters. In 2011, two consecutive earthquakes occurred in Van region, eastern part of Turkey in a three-week period. United States Geological Survey (USGS) reported the magnitudes as 7.1 and 5.6 with focal depths of 16 km and 5 km, respectively. Teams from the Earthquake Engineering Research Center (EERC) of Middle East Technical University (METU) visited the site after each earthquake and made a reconnaissance survey, which enabled to monitor the damage distributions and structural deficiencies. In this study, the damage accumulation at Van city and Ercis district is summarized by focusing on approximately 100 structures, surveyed after both earthquakes. The observed structural damages as well as the parameters affecting damage are discussed based on statistical data collected from site observations.
Investigating the Effects of a Novel Combined Infrared-Vacuum Dryer on the Drying Kinetics and Quality Parameters of Apple Chips
(Iranian Institute of Research and Development in Chemical Industries, 2023) Uğurlu, S.; Aldemir, A.; Bakkalbaşı, E.
In this study, the kinetic and quality parameters of apple chips dried by a novel dryer equipped with two-way infrared heating (180, 275, and 325 W) and vacuum pump systems (100 and 400 mmHg) were investigated. The final drying time of the sample was reduced with the increasing infrared power. However, it significantly decreased with the increasing vacuum pressure at only 180 W. While the rehydration ratio and sugar content decreased at higher infrared power, the degree of browning and 5-hydroxymethylfurfural increased. Apple chips had high HMF contents (205.39-351.30 mg/kg DM). After sensory evaluation, the highest color, crispness, chewiness, taste, and general acceptance values were determined in the apple chips dried at 275 W and 400 mmHg. The results showed that Midilli’s model was the best option to describe the experimental drying data. The effective moisture diffusivity increased with increasing power and ranged from 1.4499 to 2.9362 × 10−8 m2/s. The activation energies of drying kinetics for 100 and 400 mmHg were 40.5507 and 36.5134 kJ/mol, respectively. Results showed that the higher energy efficiency and product quality for apple chips could be obtained with a specially designed infrared vacuum combined dryer (275 W and 400 mmHg). © 2023, Iranian Institute of Research and Development in Chemical Industries. All rights reserved.
Isotherm, Kinetic and Thermodynamic Studies of Methylene Blue Adsorption Using Leucaena Leucocephala
(Yildiz Technical University, 2021) Kul, A.R.; Aldemir, A.
In recent years, great focused has been placed on the development of low-cost adsorbents to be used for applications regarding treatment of wastewater. In this study, Leucaena leucocephala peel (LLP) was used for adsorption of methylene blue from aqueous solutions. The experiments were conducted at seven concentrations (15, 30, 45, 60, 75, 90, 105 mg L-1) and three temperatures (298, 308, 318 K). The obtained data were applied to adsorption isotherm, kinetic and thermodynamic calculations. The results showed that Freundlich isotherm was more appropriate compared to Langmuir and Temkin isotherms. The kinetic results indicated that the process fitted pseudo second order model with higher R2 values compared to pseudo first order and intra-particle diffusion models. Gibbs free energy, enthalpy and entropy values were calculated for 298 K as 2.776 kJ mol-1, 6.262 kJ mol-1 and 11.699 J mol-1, respectively. © Yildiz Technical University, Environmental Engineering Department. All rights reserved.
Optimization of Aniline Biopolymerization Reaction Conditions by Response Surface Methodology (Rsm)
(Science and Engineering Research Support Society, 2014) Aldemir, A.; Birhanlı, E.; Aktaş, N.; Yeşilada, Ö.
Response Surface Methodology(RSM) was applied to enzymatic polymerization of aniline, which was conducted in a closed system containing sodium acetate buffer and presence of poly(sodium 4-styrene sulfonate) (SPS) polyelectrolyte as a template with laccase enzyme to produce water soluble polyaniline. Laccase enzyme used as catalyst was isolated from Trametes versicolor (ATCC 200801). The enzymatic polymerization rate of aniline based on measurements of initial dissolved oxygen (DO) consumption rate in the closed system, was optimized by the application of RSM. The independent variables, which had been found the most effective variables on the initial DO consumption rate by screening experiments, were determined as monomer concentration, medium temperature and medium pH. A quadratic model was developed through RSM in terms of related independent variables to describe the initial DO consumption rate as the response. Based on statistic analysis, optimum reaction conditions for the maximum initial DO consumption rate determined 42.50 mM, 39.34 °C and 5.45 as monomer concentration, medium temperature and medium pH, respectively. © 2014 SERSC.
Removal of Thymol Blue From Aqueous Solution by Natural and Modified Bentonite: Comparative Analysis of Ann and Anfis Models for the Prediction of Removal Percentage
(University of Tehran, 2021) Koyuncu, H.; Aldemir, A.; Riza Kul, A.; Canayaz, M.
In this study natural bentonite (NB) and acid-thermal co-modified bentonite (MB) were utilized as adsorbents for the removal of Thymol Blue (TB) from aqueous solution. The batch adsorption experiments were conducted under different experimental conditions. The artificial neural network (ANN) and adaptive neuro fuzzy inference systems (ANFIS) were applied to estimate removal percentage (%) of TB. Mean squared error (MSE), root mean square error (RMSE) and coefficient of determination (R2) values were used to evaluate the results. In addition, the experimental data were fitted isotherm models (Langmuir, Freundlich and Temkin) and kinetic models (pseudo first order (PFO), pseudo second order (PSO) and intra-particle diffusion (IPD)). The adsorption of TB on both the NB and MB followed well the PSO kinetic model, and was best suited Langmuir isotherm model. When the temperature was increased from 298 K to 323 K for 20 mg/L of TB initial concentration, the removal percentage of TB onto the NB and MB increased from 74.91% to 84.07% and 81.19% to 93.12%, respectively. This results were confirmed by the positive ΔH° values indicated that the removal process was endothermic for both the NB and MB. The maximum adsorption capacity was found as 48.7805 mg/g and 117.6471 mg/g for the NB and MB, respectively (at 323 K). As a result, with high surface area and adsorption capacity, the MB is a great candidate for TB dye removal from wastewater, and the ANFIS model is better than the ANN model at estimating the removal percentage of the dye. © 2021 University of Tehran.