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Öğe Batch and fixed-bed column adsorption of crystal violet and safranin by zero-valent iron (nZVI) and nZVI-modified S. cerevisiae(DESALINATION PUBL, 2018) Guler, Ulker Asli; Kundakci, OzgeBatch and continuous studies were conducted to examine the adsorption and degradation of zero-valent iron (nZVI) and nZVI-modified S. cerevisiae (magnetic yeast) to remove crystal violet (CV) and safranin (SF) from synthetic wastewater. The nZVI and magnetic yeast were characterized using FTIR, SEM, EDX, and BET analysis. pH, initial dye concentration, contact time, adsorbent dosage, temperature, ion selectivity, and the effect of ionic and cationic strength were examined. The adsorption equilibrium data are an excellent fit to the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. Different adsorption kinetics were used to examine the removal process of CV and SF, which followed a pseudo-second-order model. Adsorption was spontaneous. The adsorption of CV and SF dyes by nZVI-alginate and magnetic biosorbent-alginate in a column was studied. Regeneration efficiency was 76-87% after two cycles.Öğe EXPERIMENTAL DATA AND MODELING FOR THE ADSORPTION/DESORPTION OF TETRACYCLINE AND DICLOFENAC ON THE AGRICULTURAL SOILS(2022) Guler, Ulker Asli; Tuncel, ElizaThe adsorption-desorption characteristics of tetracycline and diclofenac onto two different agricultural soils (S1 and S2) were investigated using the batch equilibrium method. The adsorption experiments were used to optimize the two variable parameters (contact time (5-120 min), initial pollutant concentration (5-300 mg/L)) on the adsorption of tetracycline and diclofenac. The adsorption kinetics for tetracycline and diclofenac onto soil are well described by a bi-exponential adsorption model characterized by fast and slow adsorption rates. Non-linear adsorption curves fitted well to the Langmuir, Freundlich and Temkin equations. The maximum adsorption capacity (qm) of tetracycline and diclofenac onto the soils S1 and S2 were calculated to be 55.90 mg/g, 41.92 mg/g, 26 mg/g and 6.42 mg/g, respectively. Kd, Koc, foc and qa values were calculated. The adsorption efficiency of tetracycline and diclofenac by the soils S1 and S2 was over 97%. The Kd parameters for the adsorption of tetracycline and diclofenac onto the soils S1 and S2 were found to be 3537 L/kg, 654 L/kg, 1669 L/kg and 3105 L/kg, respectively. The reversibility of the adsorption process was evaluated by desorption experiments using different concentrations of HDTMA and Triton-x surfactants. The desorption rates were higher for diclofenac than for tetracycline.Öğe Investigation of the adsorption of Astrazon Blue FGRL dye in synthetic wastewater using waste mine clay(2021) Özyonar, Fuat; Kobya, Mehmet; Guler, Ulker AsliIn this investigation is aimed at the removal of Astrazon Blue FGRL (AB FGRL) (basic dye) from an aqueous solution using waste clay (MC) obtained from the gold mine area. The natural clay was characterized and identified using X-ray diffraction (XRD) analysis.Then, the contact time, adsorbent dosage, pH, initial dye concentration and temperature experiments were carried out in a batch system. The removal efficiency was found to be 97% at pH 7, 80 min, 30oC, 4 g/L MC dosage, 50 mg/L initial dye concentration. The adsorption data are applied to the Langmuir, Freundlich, and Temkin isotherm models. The maximum capacity of waste mine clay (MC) was found to be 191.75 mg/g. The pseudo-second-order kinetic models and Elovich kinetic model were used to examine the adsorption process of Astrazon Blue FGRL. The results of kinetic experiments were defined by the pseudo-second-order model point out a chemisorption reaction. The adsorption thermodynamics were investigated using parameters such as enthalpy change (?Ho), Gibbs free energy change (?Go) as well as entropy change (?So). These calculations reveal that sorption of Astrozon Blue FGRL is endothermic, spontaneous and enthalpy driven. This work provides guidance for using of waste clay materials for applications in the adsorption removal of dye from aqueous solution.Öğe Investigation of the removal of color and heavy metal from wastewater using activated sludge continuous system and application of models(Elsevier, 2024) Cebeci, Meltem Sarioglu; Guler, Ulker AsliIn the continuous system studies, the natural state of the activated sludge was used in the fixed bed column and fluidized bed column, and the studies were carried out with the synthetic solution wastewater similar to the metal coating industry. Experiments at operating conditions of bed heights 20 cm, initial Cu2+, Ni2+, and Methylene Blue concentrations of 100 mg/L, pH 5.0 and flow rates 2 mL/min were performed to study the performance of the fixed bed column and fluidized bed column. It is seen that the removal efficiencies of the fixed bed and fluidized bed column are very close to each other. Thomas, Yoon-Nelson and Bohart-Adams models were applied to the data obtained in the fixed bed column system. It has been observed that there is a good agreement between the experimental breakthrough curves and the model predictions. In addition, regeneration of activated sludge with 0.1 M HCl and a reuse experiments were carried out, and it was observed that the efficiency decreased considerably in the second use. The results are promising and shall serve to design the activated sludge based fixed bed column and fluidized bed column to obtain cleaner and sustainable treatment of industrial wastewaters containing Cu, Ni and Methylene Blue.Öğe Mann-Kendall trend analizi ile Sivas ilindeki sıcaklık ve yağış trendlerinin belirlenmesi(2022) Karakuş, Can; Guler, Ulker AsliBu çalışmanın amacı; Sivas ilindeki 9 meteoroloji istasyonu için sıcaklık ve yağış trendlerinin ortaya konulmasıdır. Bu meteoroloji istasyonlarının farklı rasat yılı aralıklarındaki sıcaklık ve yağış verileri (Sivas Merkez (1929-2019), Kangal (1959-2019), Suşehri (1970-2019), Zara (1964-2019), Divriği (1959-2019), Gemerek (1963-2019), Gürün (1964-2019), Şarkışla (1963-2019) ve Ulaş (1957-2019)) Sivas Meteoroloji Müdürlüğü’nden temin edilmiştir. Mann-Kendall trend testi yardımıyla ilkbahar, yaz, sonbahar, kış ve yıllık periyot için trend analizi gerçekleştirilmiştir. Gürün ve Ulaş ilçeleri dışındaki tüm istasyonlarda yıllık ortalama sıcaklık değerlerinin istatistiksel açıdan anlamlı bir artış trendi gösterdiği belirlenmiştir. Yıllık ortalama yağış değerleri açısından ise Kangal, Şarkışla ve Ulaş ilçelerinde istatistiksel açıdan anlamlı bir azalış trendi görülmüştür. Sivas Merkez istasyon için sıcaklık değerleri ortalama 2 oC artış göstermiş, yağış değerleri ise 10 mm azalış göstermiştir. Çalışma alanının genelinde sıcaklıklar artış göstermiş, Şarkışla ve Ulaş ilçelerinde yağış değerleri azalmıştır. Bu çalışma, sıcaklık ve yağış trendlerindeki değişimlerin çalışma alanındaki iklim değişikliği olgusunu desteklediğini ortaya koymuştur. Çalışma sonuçlarının iklim kaynaklı risklere ve su kaynakları yönetimine yardımcı olması beklenmektedir.Öğe Mono and binary component biosorption of Cu(II), Ni(II), and Methylene Blue onto raw and pretreated S. cerevisiae: equilibrium and kinetics(TAYLOR & FRANCIS INC, 2014) Guler, Ulker Asli; Sarioglu, MeltemThe mono and binary biosorption of Cu(II) ions, Ni(II) ions, and Methylene Blue dye onto raw and pretreated S. cerevisiae was investigated in a batch system. The biosorption mechanism was characterized by FT-IR, XRD, and SEM analyses. The effects of pH, contact time, initial pollutant concentration, temperature, and biosorbent dosage on the biosorption studies were determined. The experimental data were analyzed by Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The results were compatible with both Langmuir and Freundlich isotherm models. The mean free energy (E) values indicated that the biosorption of Cu(II), Ni(II), and Methylene Blue onto raw and pretreated S. cerevisiae took place by chemical-ion exchange. Kinetic data fitted well into the pseudo-second-order model. The calculated thermodynamic parameters (Delta H, Delta S, and Delta G) showed that the biosorption of Cu(II), Ni(II), and Methylene Blue onto raw and pretreated S. cerevisiae was exothermic and spontaneous. Desorption, ion selectivity, and the effect of ionic strength (NaCl) studies were also conducted. Competitive biosorption of binary mixtures of Cu(II), Ni(II), and MB was investigated in terms of biosorption capacity and found that the biosorption capacity of biosorbent decreased with increasing competing pollutant concentration.Öğe Mono and simultaneous removal of crystal violet and safranin dyes from aqueous solutions by HDTMA-modified Spirulina sp.(INST CHEMICAL ENGINEERS, 2016) Guler, Ulker Asli; Ersan, Mehtap; Tuncel, Eliza; Dugenci, FerideThe process of mono and binary removal of crystal violet and safranin dyes by Spirulina sp. (blue-green algae) modified with cationic surfactant is evaluated. The surfactant used was hexadecyltrimethylammonium bromide (HDTMA). Spirulina sp. was cultivated in Zarrouk's medium. The adsorptive properties of the modified Spirulina sp. (HDTMA-algae) were tested as a function of pH (2-10), contact time (5-180 min), temperature (25-45 degrees C, and initial dye concentrations (25-300 mg/L) and characterized with FTIR, SEM, EDX, XRD and BET analyses. The specific surface area of HDTMA-algae was 0.1990 m(2)/g. The data were fitted to non-linear Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models and non linear pseudo-first-order and pseudo-second-order kinetic models. The adsorption was 75% and 88% at pH 2 for Crystal Violet and Safranin dye, respectively. The maximum adsorption capacities were 101.87 mg/g and 54.05 mg/g and the k(F) values were 0.96 L/g and 3.56 L/g for Crystal Violet and Safranin, respectively. The kinetics of Crystal Violet and Safranin dyes onto HDTMA-algae were best described by the pseudo-second-order kinetic model. The negative values of free energy and enthalpy change indicated the feasibility, spontaneity, and exothermic nature of the adsorption process. Also, binary adsorption of Crystal Violet and Safranin dyes onto HDTMA-algae from binary dye mixtures is compared. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.Öğe Potential of pumice modified with iron(III) for copper removal from aqueous solutions(Wroclaw University of Science and Technology, 2017) Guler, Ulker Asli; Cebeci, Meltem SariogluIron-modified pumice (Fe-P) was prepared by the ion-exchange method using natural pumice from Kayseri, Turkey at room temperature without calcination. SEM, FTIR, XRD, and SBET measurement were used to investigate the copper removal mechanism. The results show that the SBET of the pumice increased from 11.88 m2/g to 21.01 m2/g after iron modification. The effects of pH, contact time, initial copper concentration, temperature, and various cations (Na+, K+, Ca2+, Mg2+ and Al3+) at various pH were investigated in batch experiments. More than 92% of Cu(II) was removed after 180 min. Langmuir, Freundlich, Dubinin–Radushkevich and Temkin isotherm models were applied to the equilibrium data at 298, 308 and 318 K. The maximum adsorption capacity at 298, 308 and 318 K was found to be 21.52, 19.48, and 19.67 mg/g, respectively. The kinetics of copper on Fe-P was best described by the pseudo-second order kinetic model. The negative values of free energy change and enthalpy change indicated that the adsorption process was feasible, spontaneous and exothermic. © 2017 Technical University of Wroclaw. All rights reserved.Öğe REMOVAL OF TETRACYCLINE FROM AQUEOUS SOLUTIONS USING NANOSCALE ZERO VALENT IRON AND FUNCTIONAL PUMICE MODIFIED NANOSCALE ZERO VALENT IRON(VILNIUS GEDIMINAS TECH UNIV, 2017) Guler, Ulker AsliNanoscale zero valent iron (nZVI) and functional pumice modified nanoscale zero valent iron (P-nZVI) were successfully synthesized and used for the removal of tetracycline (TC). These materials were characterized by SEM, TEM, XRD, FTIR, BET. Different factors such as the mass ratio, dosage of adsorbent, pH, initial TC concentration and temperature were investigated. Based on these results; a possible removal mechanism was proposed including TC adsorption and TC reduction via oxidation of Fe-0 to Fe3+. In addition, isotherm and thermodynamic parameters were applied to the equilibrium data. The maximum adsorption capacity of TC by nZVI and P-nZVI was 105.46 mg/g and 115.13 mg/g, respectively. Adsorption and reduction kinetics were examined for the TC removal process. The pseudo-second-order model and pseudo-first-order model was observed for adsorption and reduction process, respectively. Finally, more than 90% of TC from aqueous solutions was removed by nZVI and P-nZVI.Öğe Removal of tetracycline from wastewater using pumice stone: equilibrium, kinetic and thermodynamic studies(BIOMED CENTRAL LTD, 2014) Guler, Ulker Asli; Sarioglu, MeltemIn this study, pumice stone was used for the removal of tetracyline (TC) from aqueous solutions. It was characterized by XRD, FT-IR, SEM and BET analyses. Cation exchange capacity of pumice stone was found to be 9.9 meq/100 g. Effect of various parameters such as solution pH (2-11), adsorbent dosage (0.5-10 g/L), contact time (2.5-120 min), initial TC concentration (5-300 mg/L) and temperature (20-50 degrees C) on TC adsorption onto pumice was investigated. Also the adsorption of TC on pumice stone was studied as a function of Na+ and Cu2+ cations changing pH from 2 to 11 using batch experiments. The best removal efficiency performance was exhibited at adsorbent dosage 10 g/L, pH 3, contact time 120 min. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were applied to the equilibrium data. The result has shown that the adsorption was favorable, physicochemical in nature and agrees well with Langmuir and Freundlich models. The maximum Langmuir adsorption capacity was found to be 20.02 mg/g. The adsorption behavior of TC on pumices stone was fitted well in the pseudo-second order kinetics model. Thermodynamic parameters calculated from the adsorption data at different temperature showed that the adsorption reaction was feasible, spontaneous and exothermic.Öğe S. cerevisiae cells modified with nZVI: a novel magnetic biosorbent for nickel removal from aqueous solutions(DESALINATION PUBL, 2016) Guler, Ulker Asli; Ersan, MehtapThe present study was conducted to evaluate the applicability of S. cerevisiae cells modified with nZVI (magnetic biosorbent) for the Ni(II) ions removal from aqueous solutions. This composite was synthesized in ethanol using a borohydride reduction method in atmospheric conditions and characterized by FTIR, XRD, and SEM analyses. Batch experiments were examined the effects of initial solution pH, magnetic biosorbent amount, contact time, initial Ni(II) concentration, and temperature. Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm models were applied to the equilibrium data. The maximum biosorption capacity of the magnetic biosorbent was found to be relatively high (54.23 mg/g). The reductive power of the Fe-0 and functional groups on the yeast cell surface contributed to the removal of Ni(II) ions. The kinetics data were best described by the pseudo-secondorder kinetics model. Thermodynamics parameters were calculated from the experimental data. Ni(II) removal onto magnetic biosorbent was favorable, physicochemical in nature. Also, the Ni(II) removal onto magnetic biosorbent decreased with increasing in Na concentration in aqueous solutions. The results of this study suggest that the magnetic biosorbent is effective for Ni(II) removal from aqueous solutions.Öğe Synthesis of hydroxyapatite/clay and hydroxyapatite/pumice composites for tetracycline removal from aqueous solutions(INST CHEMICAL ENGINEERS, 2015) Ersan, Mehtap; Guler, Ulker Asli; Acikel, Unsal; Sarioglu, MeltemSynthesized hydroxyapatite/clay (HA-C) and hydroxyapatite/pumice (HA-P) composites were used for tetracycline (TC) uptake studies from aqueous solution and their uptake capacities were compared. HA-C and HA-P composites were synthesized by precipitation method and the structures of the synthesized composites were characterized by XRD, SEM and BET analyses. Cation exchange capacities of HA-C and HA-P were found to be 84 meq/100 g and 33 meq/100 g, respectively. The TC adsorption using HA-C and HA-P was studied on batch mode. Various parameters such as contact time, solution pH, initial TC concentration, composite dosage, salinity and temperature were optimized. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models were applied to the equilibrium data. The maximum adsorption capacity onto HA-C was found to be 76.02 mg/g and about four times larger than the adsorption capacity of the HA-P (17.87 mg/g). The results indicated that the TC uptake onto HA-C and HA-P composites is mainly by a surface complexation and ion-exchange mechanism which depend on the solution pH. The calculated values of thermodynamic parameters indicated that the TC adsorption is favorable, physicochemical in nature. The sorption process follows pseudo-second-order and intraparticle diffusion kinetic models. The TC adsorption mechanism by HA-C and HA-P has been proposed. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
