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    Adsorption of some highly toxic dyestuffs from aqueous solution by chitin and its synthesized derivatives
    (Elsevier Science Bv, 2009) Akkaya, Guelbahar; Uzun, Ilhan; Guzel, Fuat
    The adsorption of indigo carmine (IC) and trypan blue (TB) by chitin was kinetically investigated as dependent on temperature and pH. Experimental data obtained at different temperatures for the adsorption of each dyestuff were applied to the pseudo first-order, the pseudo second-order and the intraparticle diffusion rate equations, and the pseudo first-order rate constants (k(1)), the pseudo second-order rate constants (k(2)) and the intraparticle diffusion rate constants (k(p)) at these temperatures were calculated, respectively. In addition, adsorption isotherms of each dyestuff by chitin were also determined at different temperatures. It was seen that adsorption isotherms fitted the H type. Chitin was then modified via ring-opening reaction with cyclic acid anhydrides (succinic, maleic and 1,2,4-benzenetricarboxylic) in lithium chloride/N,N-dimethylacetamide. Chitin derivatives obtained were compared according to their capabilities to adsorb IC and TB. It was determined that IC and TB were more adsorbed by chitin modified with 1,2,4-benzenetricarboxylic anhydride (CBA) and chitin modified with maleic anhydride (CMA), respectively. 31.33% of IC (C-0: 300 ppm) by CBA, and 44.29% of TB (C-0: 200 ppm) by CMA were adsorbed. Then, the adsorption of IC by CBA and of TB by CMA was kinetically investigated as dependent on temperature. The constants k(1), k(2) and k(p) related to the adsorption of IC by CBA and of TB by CMA were calculated as stated above. (C) 2009 Elsevier B.V. All rights reserved.
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    Bioremoval and recovery of Cu(II) and Pb(II) from aqueous solution by a novel biosorbent watermelon (Citrullus lanatus) seed hulls: Kinetic study, equilibrium isotherm, SEM and FTIR analysis
    (Desalination Publ, 2013) Akkaya, Guelbahar; Guzel, Fuat
    The biosorption of Cu(II) and Pb(II) ions from aqueous solutions using a new sorbent, watermelon seed hulls (WSH), has been studied. The effect of pH (2-6), biosorbent dose (0.1-1.0g), initial metal ion concentration (10-500mgL(-1)), contact time (5-270min), and temperature (293-333K) was investigated. Equilibrium adsorption isotherms and kinetics were also investigated based on metals adsorption tests. The experimental data were analyzed by the Langmuir and Freundlich models of adsorption, and the results fitted well to the Langmuir isotherm. The kinetic data have been analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The experimental data fit very well with the pseudo-first-order kinetic model. The data obtained from adsorption isotherms at different temperatures were used to calculate some thermodynamic quantities, such as free energy (G(o)), standard enthalpy (H-o), and standard entropy (S-o), were evaluated. The adsorption of these two metals on the WSH was found to be spontaneous and endothermic process in nature. Desorption experiments were carried out using various acid solutions with a view to regenerate the spent adsorbent and to recover the both adsorbed metal ions. According to the experimental results, WSH seems to be an effective, low-cost and alternative adsorbent precursor for the removal of Cu(II) and Pb(II) ions from aqueous solutions.
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    Öğe
    Optimization of Copper and Lead Removal by a Novel Biosorbent: Cucumber (Cucumis Sativus) Peels-Kinetic, Equilibrium, and Desorption Studies
    (Taylor & Francis Inc, 2013) Akkaya, Guelbahar; Guzel, Fuat
    Cucumber peels biosorption efficiency for copper(II) and lead(II) was studied in batch mode. The optimum conditions for removal of Cu(II) and Pb(II) ions were found to be pH 5.0, biosorbent dose of 0.1g, contact time of 60 and 85 minutes, and initial concentration of 100 and 150mg/L, respectively. The kinetic data were best described by pseudo-second order model. The biosorption process followed by the Langmuir isotherm model. Maximum monolayer biosorption capacities were 88.50 and 147.06mg/g for Cu(II) and Pb(II) ions, respectively. Thermodynamic parameters suggest that the biosorption process is spontaneous and endothermic. Desorption studies were carried out with different desorbing agents.