Browsing by Author "Koyuncu, H."

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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] .
Determination of Genotoxic Effects of Hookah Smoking by Micronucleus and Chromosome Aberration Methods
(International Scientific Literature Inc., 2016) Eker, E.D.; Koyuncu, H.; Şahin, N.Ö.; Yüksel, A.; Berköz, M.; Diler, S.B.; Akgül, S.A.
Background: Use of a hookah (a type of water pipe) is a traditional way of smoking tobacco, particularly in the Middle East. In Turkey, its popularity has been growing in recent years, especially among young people. It is known that cigarette smoking has genotoxic effects and causes mutations, but no comprehensive study has been done on the genotoxic effects of hookah usage, particularly in Turkey. Material/Methods: We collected peripheral blood/buccal smear samples from 30 subjects who did not smoke cigarettes but who regularly smoke a hookah an average of 2 times per week, and from 30 control subjects who had never smoked cigarettes or a hookah. Chromosome analyses were performed on the samples obtained from peripheral blood of each individual, 25 metaphase plaques were counted for each, and chromosome/chromatid breakage/gap parameters were evaluated. Micronucleus analysis was done on buccal smear samples and micronucleus/binucleus parameters were investigated by counting 2000 cells of each individual. Results: Chromosome breakage ratios were found to be 0.64±0.86 and 0.46±0.71 in the study and control groups, respectively, while chromatid breakage ratios were 0.53±0.83 and 0.53±0.71; fragment ratios were 0.82±1.24 and 0.21±0.49 (p<0.05); and gap ratios were 0.57±0.83 and 0.18±0.53 (p<0.05), respectively. Micronucleus ratio was 6.03±2.06 and 4.43±2.27 (p<0.05) in the study and control groups, respectively, and binucleus ratios were 8.53±3.23 and 12.15±5.18, respectively (p<0.05). Conclusions: Results of our study reveal significant statistical differences between the individuals who smoked hookah and those who did not in terms of fragment, gap, micronucleus, and binucleus parameters, suggesting that smoking a hookah may cause genotoxic effects. © Med Sci Monit.
Removal of Heavy Metals Using Lichen-Derived Activated Carbons: Adsorption Studies, Machine Learning, and Response Surface Methodology Approaches
(Springer, 2025) Koyuncu, H.; Kul, A. R.; Akyavasoglu, O.
Biomass-based activated carbons are promising as they are effective and low-cost for wastewater remediation. In this study, the removal of lead, copper, and zinc was investigated using activated carbons obtained from two different lichens. The performance of the 5th-order Response Surface methodology (RSM), Machine Learning (ML), and Artificial Neural Network (ANN) model based on Face-Centered Central Composite Design (FCCCD) was evaluated considering initial concentration, temperature, and time effects. The effectiveness of using ANN for accurate prediction in lead and copper removal and the superior performance of ML-based 5th-order RSM for zinc removal were demonstrated. Among the Langmuir, Freundlich, and Temkin isotherm models, the Freundlich model best described the adsorption processes, and the Langmuir maximum adsorption capacities were found to be 105.26 mg/g (Pb/AC-1), 59.52 mg/g (Cu/AC-1), and 53.19 mg/g (Cu/AC-2). Additionally, the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were examined, and it was found that the adsorption processes followed the pseudo-second-order kinetics and intra-particle diffusion played a significant role. The activation energies and Delta H0 values less than 40 kJ/mol and Delta G0 values below - 20 kJ/mol showed that the metals were adsorbed by physical mechanisms. The novelty of this study is that the 5th-order RSM model is applied to adsorption processes for the first time, and a multi-faceted approach is used to analyse adsorption processes, including machine learning and ANN, isotherm modeling, thermodynamic evaluation, kinetics analysis, and activation energy calculations.
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.