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Öğe Adsorption of crystal violet from aqueous solution on activated carbon derived from Gölbaşi lignite(2012) Depci T.; Kul A.R.; Onal Y.; Disli E.; Alkan S.; Turkmenoglu Z.F.Activated carbon (AC) was obtained from lignite of the local resource, Gölbaşi{dotless};- Adi{dotless};yaman (Turkey) by chemical activation. The Gölbaşi{dotless}; lignite was chosen as the precursor for its availability and low cost. The BET surface area of the activated carbon was found 921 m2/g. The AC was used as an adsorbent for Crystal Violet (CV) in aqueous solution. The adsorption properties of CV onto the activated carbon are discussed in terms of the adsorption isotherms (Langmuir and Freundlich) and the kinetic models (pseudo-first-order, pseudo-second-order and intraparticle diffusion model). It was shown that the experimental results best fitted by the Langmuir model, and the second-order kinetic equation. The thermodynamic parameters show that the adsorption process is endothermic. The experimental results point out that the obtained activated carbon is a viable candidate for sorbent removing CV from aqueous solutions.Öğe Characteristic properties of adsorbed catalase onto activated carbon based adiyaman lignite(2011) Depci T.; Alkan S.; Kul A.R.; Önal Y.; Alacabey I.; Dişli E.Catalase is one of the most common and important enzymes in biological systems. However, its purification process has some difficulties and it can be easily decomposed in aqueous or nonaqueous solutions. Therefore, a catalase should be adsorbed on solid materials to reduce its inactivation and to increase its economic value. Activated carbon which was obtained from Turkish low-rank coal (Gölbaşi-Adiyaman) by chemical activation was used as a solid carrier to adsorb catalase for the first time in this research. The pore structure of the activated carbon was determined by A Tri Star 3000 (Micromeritics, USA) surface analyzer and scanning electron microscope. In order to determine adsorption properties of catalase, ionic strength effect, temperature-activity, pH-activity, storage stability and operational stability of the activated carbon were investigated. The kinetic and thermodynamic mechanisms of adsorbed enzyme were also studied. The experimental results pointed out that the obtained activated carbon is a viable candidate for an alternative solid carrier for catalase and it may be a promising material for various biotechnological applications. © by PSP.Öğe Equilibrium, kinetic and thermodynamic studies of nickel adsorption onto natural and modified kaolinites(2011) Kul A.R.; Depci T.; Alacabey I.; Alkan S.; Onal Y.Availability of clay and its modified forms makes them a viable candidate for an alternative adsorbent.this study, kaolinite and modified kaolinites were tested to determine their suitability for removal of Ni (II) ions from aqueous medium. Parameters, such as kaolinite type, concentration of Ni ions, time and temperature of interaction, were investigated to evaluate the adsorption capacity, kinetics, equilibrium and thermodynamic properties of Ni (II) adsorption. The adsorption isotherms followed Freundlich, Dubinin-Redushkevich (D-R) and Halsey isotherms but DR isotherm was chosen due to its applicability to all adsorption isotherms. The kinetics of adsorption mechanism of Ni (II) was tested using pseudo-first-order, pseudosecond-order and intraparticle diffusion models. The results showed that adsorption mechanism could be perfectly explained with pseudo-second order equation. The intraparticle diffusion of Ni (II) ions within the natural and modified kaolinite was more likely to be governed by the diffusion step. Adsorption mechanism for activated kaolinite was intra-particle diffusion model. Ni (II) adsorptions on activated kaolinites were exothermic and spontaneous in nature. The results of this study indicated that activated kaolinite can be employed for removal of Ni (II) from industrial wastewater. © by PSP.
