Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2016/r/gumushane/15022
  A novel carrier element-free co-precipitation method for separation/preconcentration of lead and cadmium ions from environmental matrices

  Bulut, Volkan Numan; Demirci, Hamit; Ozdes, Duygu; Gundogdu, Ali; Bekircan, Olcay; Soylak, Mustafa; Duran, Celal

  A new separation and pre-concentration method was presented in this study for two trace heavy metal ions, lead (Pb2+) and cadmium (Cd2+) from aqueous solutions, based on a carrier element free co-precipitation (CEFC) method using a triazole derivate, 3-(4-tert-butylphenyl)−5-phenyl-4-(2-hydroxy-5-methoxybenzylamino)−4H-1,2,4-triazole as an organic co-precipitating agent. The method was optimized with some analytical parameters which affect the quantitative recoveries of study metals. According to the results, optimum pH of solution, quantity of co-precipitating agent, centrifugation and incubation time, and sample volume were determined as 6.0, 1.5 mg, 10 min, and 10 min, and 100 mL, respectively. In addition, no significant matrix interferences were observed over the recovery of the metal ions. For analytical figure of merit, RSD values of the method were found as 5.7 and 4.8 for Pb2+ and Cd2+, respectively. LOD values were also calculated as 2.0 µg L−1 for Pb2+ and 0.2 µg L−1 for Cd2+. The accuracy of method was checked with spiked/recovery tests and analysis of a standard reference material. The developed method was finally applied to the real liquid/solid samples under the optimum conditions.

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• MakaleYalnız künye2015/r/gumushane/13372
  Equilibrium, kinetics, and thermodynamic evaluation of mercury (II) removal from aqueous solutions by moss (Homalothecium sericeum) biomass

  Ozdes, Duygu; Duran, Celal

  In the present research, Homalothecium Sericeum was utilized for the first time as an effective and readily available adsorbent in removal of Hg(II) ions from aqueous solutions through a batch adsorption technique. The effects of initial solution pH, contact time, initial Hg(II) and adsorbent concentration, temperature, and ionic strengths were evaluated on the removal efficiency of Hg(II) ions, after being characterized of H. sericeum by different techniques. The maximum Hg(II) adsorption was obtained as 128.2 mg g-1 at initial pH 6.0 with an equilibrium time of 60 min, adsorbent dosage of 5.0 g L-1 and initial Hg(II) concentration range of 50-750 mg L-1. The adsorption behaviors of Hg(II) ions onto H. sericeum were investigated in terms of kinetics (pseudo-first order, pseudo-second order, and intraparticle diffusion models), isotherms (Langmuir, Freundlich, and Dubinin Radushkevich models), and thermodynamics evaluation. Both the Langmuir and Freundlich isotherm models were found to be suitable to describe the adsorption equilibrium while the adsorption kinetics followed by the pseudo-second order model. Thermodynamic parameters including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes indicated that the adsorption of Hg(II) ions onto H. sericeum was feasible, spontaneous, and endothermic in nature.

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