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    ADSORPTION OF CRYSTAL VIOLET FROM AQUEOUS SOLUTION ON ACTIVATED CARBON DERIVED FROM GOLBASI LIGNITE
    (Oficyna Wydawnicza Politechniki Wroclawskiej, 2012) Depci, Tolga; Kul, Ali Riza; Onal, Yunus; Disli, Erkan; Alkan, Salih; Turkmenoglu, Z. Funda
    Activated carbon (AC) was obtained from lignite of the local resource, Golbasi - Adiyaman (Turkey) by chemical activation. The Golbasi 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.
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    Adsorption of Crystal Violet on Activated Carbon Prepared from Coal Flotation Concentrate
    (Iop Publishing Ltd, 2016) Aydogmus, Ramazan; Depci, Tolga; Sarikaya, Musa; Kul, Ali Riza; Onal, Yunus
    The objective of this study is firstly to investigate the floatability properties of Zilan-Van coal after microwave irradiation and secondly to produce activated carbon from flotation concentrate in order to remove Crystal Violet (CV) from waste water. The flotation experiments showed that microwave heating at 0.9 kW power level for 60 sec exposure time enhanced the hydrophobicity and increased the flotation yield. The activated carbon with remarkable surface area (696 m(2)/g) was produced from the flotation concentrate and used to adsorb CV from aqueous solution in a batch reactor at different temperature. The adsorption properties of CV onto the activated carbon are discussed in terms of the adsorption isotherms (Langmuir and Freundlich) and found that the experimental results best fitted by the Langmuir model.
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    CHARACTERISTIC PROPERTIES OF ADSORBED CATALASE ONTO ACTIVATED CARBON BASED ADIYAMAN LIGNITE
    (Parlar Scientific Publications (P S P), 2011) Depci, Tolga; Alkan, Salih; Kul, Ali Riza; Onal, Yunus; Alacabey, Ihsan; Disli, Erkan
    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 (Golbasi-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.
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    Competitive adsorption of lead and zinc from aqueous solution on activated carbon prepared from Van apple pulp: Study in single- and multi-solute systems
    (Elsevier Science Sa, 2012) Depci, Tolga; Kul, Ali Riza; Onal, Yunus
    The potential of activated carbon (VAAC) prepared from local agricultural waste, apple pulp, as an alternative low-cost adsorbent was investigated for the removal of lead and zinc from single- and multi metal aqueous solution. VAAC was produced with a reasonable yield, 43% and has remarkable surface area (1067.01 m(2)/g) with a well-developed pore structure. To determine the adsorption process and properties, the effects of various operating parameters, pH of the solutions (2-6), adsorbent dosage (0.01-0.2 g), initial concentration of metal ions (25-40 mg/L), contact time (3-120 min) and temperature (298-308 K) were investigated in a batch adsorption technique. The adsorption isotherm data were better fitted by Langmuir model. The pseudo second-order model was found more applicable to describe the kinetic of system in both the single- and multi-solute system. The adsorption capacities of heavy metals decrease in the order of Pb(II) (15.96 mg/g) < Pb (Pb + Zn) (13.23 mg/g) < Zn(II) (11.72 mg/g) < Zn (Pb + Zn) (7.54 mg/g) at 298 K. Although individual metal ions adsorption decreases in multi-system. the more metal ions are adsorbed (20.77 mg/g). The intraparticle diffusion model, external mass transfer coefficient, film and pore diffusion coefficient at different temperatures were also evaluated to investigate the adsorption mechanisms of both systems. The adsorption was mainly controlled film diffusion process at all operating temperatures and concentrations. The thermodynamic parameters indicate that the adsorption process is endothermic, feasible and thermodynamically favored. (C) 2012 Elsevier B.V. All rights reserved.
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    A new statistical physics model to interpret the binary adsorption isotherms of lead and zinc on activated carbon
    (Elsevier Science Bv, 2016) Sellaoui, Lotfi; Depci, Tolga; Kul, Ali Riza; Knani, Salah; Ben Lamine, Abdelmottaleb
    New statistical physicochemical interpretations of an adsorption process at molecular level were developed to explain the binary adsorption isotherms of lead and zinc ions on activated carbon derived from Styrax officinalis seeds (Balikesir, Turkey) and a commercial activated carbon at different temperatures, 298, 308 and 318 K. The extended Hill model was developed to explain heterogeneous model in terms of the grand canonical ensemble in statistical physics. Steric and energetic parameters, like the numbers of ions per site n(1) and n(2), the densities of receptor sites N-M1 and N-M2 and the adsorption energies (-epsilon(1)) and (-epsilon(2)) were directly obtained from the fitting of the experimental adsorption isotherms by numerical simulation to describe the process. The simulation results suggested that two adsorbates per site were anchored on activated carbon surface. The magnitudes of the calculated adsorption energies indicated that Zn2+ and Pb2+ were physically adsorbed by the activated carbon. Thermodynamic potential functions, namely entropy, enthalpy and internal energy were calculated to explain the order and disorder of the adsorbate at the adsorbent surface during the binary adsorption process. The values of the free enthalpy and the internal energy indicated spontaneous adsorption process. (C) 2015 Elsevier B.V. All rights reserved.