Sürdürülebilir Kalkınma Amaçları
Yayınlar
- Book ChapterYalnız künye2015Removal of Organic Dyes from Industrial Effluents: An Overview of Physical and Biotechnological Applications
Ejder-Korucu, Mehtap; Gürses, Ahmet; Dogar, Çetin; Sharma, Sanjay K.; Açikyildiz, Metin; Sharma, SK
The textile industry produces a large amount of dye effluents, which are highly toxic as they contain a large number of metal complex dyes. The use of synthetic chemical dyes in various industrial processes, including paper and pulp manufacturing, plastics, dyeing of cloth, leather treatment and printing has increased considerably over the last few years, resulting in the release of dye-containing industrial effluents into the soil and aquatic ecosystems. The textile industry generates highly polluted wastewater and its treatment is a very serious problem due to high total dissolved solids (TDS), the presence of toxic heavy metals and the non-biodegradable nature of the dyestuffs present in the effluents. There are many processes available for the removal of dyes by conventional treatment technologies including biological and chemical oxidation, coagulation and adsorption, but they cannot be effectively used individually. Many approaches, including physical, chemical and/or biological processes have been used in the treatment of industrial wastewater containing dye, but such methods are often very costly and not environmentally safe. Furthermore, the large amount of sludge generated and the low efficiency of treatment with respect to some dyes have limited their use.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2014The investigation of electrokinetic behaviour of micro-particles produced by CTA + ions and Na-montmorillonite
Gürses, Ahmet; Güneş, Kübra; Mindivan, Ferda; Korucu, Mehtap Ejder; Açikyildiz, Metin; Doʇar, Çetin
In this study, the interactions between clay platelets and CTA + ions in aqueous dispersions of Na-montmorillonite (Na-MMT) were examined in detail by using electro kinetic parameters such as electrical conductivity and zeta potential and by considering XRD patterns and d-spacing values of the organoclay samples as a function of both surfactant concentration (CTAB, cetyltrimethylammonium bromide) and clay amount. The amounts adsorbed and zeta potentials of the particles increased with an increase in the initial concentration of CTAB in parallel with the electrical conductivity values. The adsorption mechanisms which predominate at certain ranges of CTAB concentration were proposed and schematized by considering the d-spacing values calculated and the zeta potential values of particles. For the different solid/liquid ratios, the initial concentrations of CTAB, in which appeared significant increases in the d-spacing values were found as 200, 280 and 300 mg/L, respectively. The d-spacing values which correspond to these concentrations are, respectively 1.82, 1.82 and 1.68 nm. It is remarkable that at first three solid/liquid ratios, a "stress region" to be related with hydrophobic binding appeared. Thermodynamic parameters such as Gibbs free energy (ΔG o ), isosteric enthalpy (ΔH o ads ) q , and isosteric entropy (ΔS o ads ) q were also calculated by using experimental data. These parameters indicate that adsorption of CTAB onto Na-montmorillonite is spontaneous and exothermic in the temperature range studied. The ((ΔS o ads ) q , (ΔH o ads ) q and (ΔG o )) values calculated are highly negative. This reveals that the adsorption of CTA + ions at the interlayer region of clay carried out with more order stacking of CTA + ions.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2010Thermodynamics 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.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010An investigation on teachers to whom positive attitudes were developed by students
Gürses, Ahmet; Çamuroǧlu, Tuba; Açikyildiz, Metin; Doǧar, Çetin; Keser, H; Ozcinar, Z; Kanbul, S
In this study, it is aimed to analyze the effects of out of school activities of teachers to whom positive attitudes were developed by the students in instructional process and heir some personal features on developed attitude. For this aim, semi-structured interviews were applied to 80 students and 10 teachers working in three different high schools under the authority of Erzurum Directorate of National Education in the first semester of the academic year 2009-2010. After the analyses of gained data, it was found that teachers' personal features are much more effective than their professional knowledge in the process of developing positive attitudes.
RDL Kalıcı Kaydıİncele - Conference ObjectAçık Erişim2010Science and social science teacher's attitudes towards project studies
Gürses, Ahmet; Tutar, Zafer A.; Doǧar, Çetin; Mindivan, Ferda; Açikyildiz, Metin; Gözöm, Seda; Keser, H; Ozcinar, Z; Kanbul, S
This study aims to determine the ideas about project and project studies of teachers working at social and science branches of high schools. To accomplish this, a survey including twenty-five items about project attitudes scale and personal information was administrated to 10 social branch teachers and 15 science branch teachers working in Erzurum, Turkey. Studies of frequency, arithmetic mean, percentage, t-test and ANOVA techniques were used to analyze the obtained data. The results show that teachers are more optimistic in social branches towards project and project studies than those working in science branches. In addition, there is no statistically meaningful relationship among science and social science teachers' approaches to project studies, teachers' experiences, academic careers and project attendance. Finally, with results, suggestions on the effective usage of project studies are given.
RDL Kalıcı Kaydıİncele - ArticleYalnız künye2006An investigation on effects of various parameters on viscosities of coal-water mixture prepared with Erzurum-Aşkale lignite coal
Gürses, Ahmet; Açikyildiz, Metin; Doǧar, Çetin; Karaca, Semra; Bayrak, Ramis
In this study the effects of parameters such as coal loading (wt.%), the initial pH of mixture, the addition of various electrolytes, surfactants and temperature on the viscosity and rheologic parameters of coal-water mixture (CWM) have been investigated. The apparent viscosity was measured with a RV8-Brookfield rotating type viscosimeter. The additives used were AlCl3 and K2HPO4 as the electrolytes and Cetyltrimethyl Ammonium Bromide (CTAB), Sodium Dodecyl Sulphate (SDS) and Borrosperse NA-3A as the surfactants. It was found that the most effective additives, in terms of the viscosity reduction, were CTAB and K2HPO4, and that the CWM which had coal concentrations up to 50% (based on the weight of dry coal) could be prepared by using each additives. In addition, the viscosities of CWM with increasing temperature were found to increase at low speed, and decrease at high speed.
RDL Kalıcı Kaydıİncele - Conference ObjectYalnız künye2005Effect 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.
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