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    Heavy metals uptake from aqueous solutions using marine algae (Colpomenia sinuosa): kinetics and isotherms
    (TAYLOR & FRANCIS LTD, 2012) Cirik, Yeliz; Bekci, Zehra Molu; Buyukates, Yesim; Ak, Ilknur; Merdivan, Melek
    The adsorption of copper, zinc, cobalt, lead and cadmium ions onto Colpomenia sinuosa was studied as a function of contact time, initial metal ion concentration and initial pH. In addition, desorption studies were performed. Characterisation of this adsorbent was also confirmed by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Batch adsorption experimental data were analysed using Langmuir, Freundlich and Dubinin-Raduschkevich (D-R) adsorption isotherms. The results indicated that the biosorption equilibrium was well described by both the Freudlich and D-R isotherms. Moreover, sorption kinetics was performed and it was observed that equilibrium was reached in <60 min, which could be described by the pseudo-second-order kinetic model for all heavy metals. The sorption of heavy metals onto the biomass was largely dependent on the initial solution pH. The elution efficiency for heavy metal ions desorption from C. sinuosa was determined for 0.1 M HCl, 1.0 M HCl and 1.0 M HNO3. Desorption efficiency and also adsorption capacity were highest for Pb(II). The results indicate that C. sinuosa has great potential for the removal of heavy metals in an ecofriendly process.
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    Zearalenone Removal in Synthetic Media and Aqueous Part of Canned Corn by Montmorillonite K10 and Pillared Montmorillonite K10
    (INT ASSOC FOOD PROTECTION, 2011) Bekci, Zehra Molu; Antep, Mine Kurtbay; Merdivan, Melek; Yurdakoc, Kadir
    The capacities of montmorillonite K10 (K10), aluminum pillared K10 (Al-K10), and iron pillared K10 (Fe-K10) to eliminate zearalenone (ZEN) from synthetic media and the aqueous part of canned corn were studied. Original clay and pillared clays were characterized in terms of X-ray powder diffraction analysis and N-2 adsorption-desorption isotherms. The maximum amounts of adsorption of ZEN by K10, Al-K10, and Fe-K10 at 25 degrees C and pH 7 were 0.202, 1.305, and 1.028 mg/g and 0.264, 0.096, and 0.255 mg/g, calculated from Langmuir and Freundlich isotherms, respectively. The adsorption of ZEN was also studied as a function of adsorbent amount (1 to 30 mg), ZEN concentration (2 to 20 mg/liter), pH of solution (pH 4 to 10), and contact time. Pillared clays could be an excellent alternative for removing ZEN in contaminated food samples and are potentially low-cost adsorbents with a promising future as an alternative to more costly materials.