Sürdürülebilir Kalkınma Amaçları
Yayınlar
- BildiriYalnız künye2012Scopus SJRQ3Biosorption of CR (VI) onto pseudevernia furfuracea /aqueous solution interface
Gürses, Ahmet; Özkan, Esra; Doǧar, Çetin
This study addresses the removal of a heavy metal, Cr (VI), from aqueous solutions by using dried Psedeuvernia furforcea biomass as biosorbent. The effects of factors, such as the initial chromium concentration, contact time, temperature, biosorbent dosage and mixing rate on biosorption of the heavy metal was investigated. Furthermore, the fitting of adsorption data on Langmuir, Freundlich, BET, Temkin, Redlich-Peterson, Henderson, Smith, Halsey and Harkins-Jura adsorption isotherm models was investigated. In order to explain the metal-functional group binding mechanisms, FTIR analysis was carried out. The sorption equilibrium time was determined to be 8 hours. The amount of Cr (VI) adsorbed onto Psedeuvernia furforcea increased with increasing sorbent dosage and increasing temperature indicating endothermic nature of biosorption process. The results suggest that the physical interactions between sorbent particles and sórbate ions play an important role for the adsorption of Cr (VI) onto the biosorbent. It was found that the biosorption data of Cr (VI) by Psedeuvernia furforcea biomass were fit on the Freundlich adsorption isotherms at 293, 313, and 333K. From the experimental results, it can be concluded that Psedeuvernia furforcea can be used as an economical sorbent in the removal of these heavy metal ions.
- BildiriYalnız künye2012Scopus SJRQ3Optimization of process parameters for removal of Cr(VI) by Hypnum cupressiforme using response surface methodology (RSM)
Özkan, Esra; Gürses, Ahmet; Açikyildiz, Metin; Güneş, Kübra
Response surface methodology was applied to optimize the removal of chromium ion by Hypnum cupressiforme from an aqueous solution. Experiments were analyzed using response surface methodology (RSM). The biosorption process was investigated as a function of five independent factors, sorption time, sorption temperature, initial ion concentration, sorbent dosage, and mixing rate. The optimum conditions for the chromium biosorption were found to be 760 min, 313K, 30mg/L, 0.01 mg/100mL, 107 min-1 respectively, for sorption time, sorption temperature, initial ion concentration, sorbent dosage, and mixing rate.
AtıfScopus2
İncele - MakaleAçık Erişim2010Scopus SJRQ1Thermodynamics and kinetic studies of biosorption of a basic dye from aqueous solution using green algae Ulothrix sp.
Doǧar, Çetin; Gürses, Ahmet; Açikyildiz, Metin; Özkan, Esra
This study addresses removal of a basic dye, methylene blue, from aqueous solutions by using dried Ulothrix sp. biomass as biosorbent. The effects of the initial dye concentration, contact time, temperature, solution equilibrium pH, biosorbent dosage, and mixing rate on biosorption of the dye have been investigated. It was found that 30 min is sufficient in order to reach adsorption equilibrium. The amount of methylene blue adsorbed onto Ulothrix sp. increased with increasing equilibrium pH and mixing rate, in contrary, it decreased with increasing temperature and sorbent dosage. The process followed the pseudo-second-order kinetic model. The isosteric enthalpy and entropy values were calculated as -11.8 kJ/mol and 37.5 J/(mol K), respectively. In addition, the results suggest that the physical interactions between sorbent particles and sorbate ions play an important role for the adsorption of methylene blue onto the biosorbent.
AtıfScopus80WoS74OpenAlex85
İncele - MakaleYalnız künye2005Alan Öğretmeni Yetiştirmede Tezsiz Yüksek Lisans Eğitiminin Sonuçlarının Değerlendirilmesi
Özkan, Esra; Yalçın, Mehmet; Açıkyıldız, Metin; Bayrak, Ramiz; Doğar, Esra; Gürses, Ahmet
Eğitim sistemleri, bilim ve teknolojideki hızlı gelişmeler ve toplumun ihtiyaç duyduğu insan gücü çerçevesinde yeniden şekillenmektedir. Öğretmen yetiştirme sistemleri de bu gelişmelerden doğrudan etkilenmekte, programlar, eğitim-öğretim süreçleri ve altyapı bakımından alternatif yaklaşımlar gündeme gelmektedir. Eğitim Fakültelerinin yeniden yapılanması süreci de bu tartışmaların bir sonucu olarak görülebilir. Bu çalışma, tezsiz yüksek lisans eğitimlerini sürdüren kimya öğretmen adaylarının ortaöğretim kimya öğretmenleriyle öğretmenlik mesleğine karşı tutumlarını karşılaştırmak amacıyla yapılmıştır. Araştırmanın örneklemini 2003-2004 yılı güz döneminde tezsiz Yüksek Lisans programına devam eden 36 kimya öğretmen adayı ve 22 ortaöğretim kimya öğretmeni oluşturmaktadır. Veri toplama aracı olarak anket kullanılmıştır (α=0,92). Yapılan anket çalışması sonuçlarından kimya öğretmen adaylarının ortaöğretim kimya öğretmenleriyle öğretmenlik mesleğine yönelik tutumları arasında önemli bir farkın olmadığı tespit edilmiştir.
AtıfTR Dizin4
İncele - BildiriYalnız künye2005Scopus SJRQ4Effect of temperature for the adsorption of methylene blue onto activated carbon produced from waste dogrose seeds
Gürses, Ahmet; Doǧar, Çetin; Açikyildiz, Metin; Özkan, Esra; Bayrak, Ramis
Activated carbon, produced from dogrose (Rosa section Caninae) seeds, was used for the removal of methylene blue (basic dye). Adsorption studies were carried out at 20°C and 40°C at various initial dye concentrations (20, 40, 60, 80, and 100 mg/L) and at different lengths of time (15, 30, 60, and 120 min). Adsorption isotherms of the basic dye on the prepared adsorbent were determined and correlated with common isotherm equations. Fitting of the isotherm data to the BET adsorption isotherm model was better in high concentration ranges than in the other models. Thermodynamic parameters such as change in isosteric adsorption enthalpy (ΔH)y and isosteric adsorption entropy (ΔS)y were also determined to 40.8 kJ and 0.141 kJ, respectively. It was concluded that the adsorption of methylene blue increases with increasing temperature. BET model fitting indicates that the hydrophobic interactions between the dye and the produced active carbon at the first layer and the dipole-dipole interactions between methylene blue molecules and the adsorbed molecules at the secondary layer predominate. To investigate the adsorptive characteristics of the produced active carbon, porosity and BET surface area measurements were made.
AtıfScopus1OpenAlex1İncele