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    A new Keggin-type polyoxometalate catalyst for degradation of aqueous organic contaminants
    (Elsevier, 2017) Olgun, Asim; Colak, Alper Tolga; Gubbuk, I. Hilal; Sahin, Onur; Kanar, Ebru
    In this study, a new polyoxometalate,K-16[Ni(H2O)(6)](2)[BW12O40]4(center dot)48H(2)O (1) was synthesized at room temperature and characterized by X-ray single crystal diffractions, elemental analyses, IR spectra, and thermo gravimetric analyses (TGA). Crystal structure analysis reveals that compound 1 exhibits a supramolecular structure containing one Keggin-type [BW12O40](4) heteropoly anion. The catalytic properties of this molecule for the degradation of Methyl red (MR), Rhodamine B (RhB), Methyl orange (MO) and Congo red (CR) were investigated. The results show that the compound 1 is a promising catalyst candidate for dye degradation. (C) 2016 Elsevier B.V. All rights reserved.
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    Adsorptive properties of molasses modified boron enrichment waste based nanoclay for removal of basic dyes
    (Elsevier Science Inc, 2016) Gupta, Vinod Kumar; Agarwal, Shilpi; Olgun, Asim; Demir, Halil Ibrahim; Yola, Mehmet Lutfi; Atar, Necip
    In this study, the removal of cationic dyes, Basic Red 46 (BR46) and Basic Blue 41 (BB41), from aqueous solution using boron enrichment waste (BW) and molasses modified boron enrichment waste (MBW) based nanoclays was presented in a batch system and fixed-bed column system. The effects of pH, contact time, initial solution concentration, adsorbent dosage, temperature of batch operation on the uptake of both dyes were investigated. The adsorption data were further performed on the basis of kinetic and isotherm models. According to the results, the dye removal capacity of MBW was higher than that of BW. The studies demonstrated that the adsorption patterns occurred according to Langmuir isotherm model and pseudo-second-order kinetic model. The adsorption of two dyes is spontaneous and exothermic in nature. Breakthrough curves obtained from fixed-bed column tests showed that column adsorption capacities provided strong evidence of the potential of the nanoclay for the technological applications of the basic dyes removal from aqueous solutions. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
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    Facile and green fabrication of silver nanoparticles on a polyoxometalate for Li-ion battery
    (Springer Heidelberg, 2015) Eren, Tanju; Atar, Necip; Yola, Mehmet Lutfi; Karimi-Maleh, Hassan; Colak, Alper Tolga; Olgun, Asim
    In the present study, we report the green and one-pot synthesis of silver nanoparticles (AgNPs) on as-prepared novel polyoxometalate {[Ni-2,Ni-5(Hpen)(4)(PW9O34)] center dot 5H(2)O} (POM) without any reducing agent and its application as improved anode material for lithium-ion batteries (LIBs). The structure of the AgNPs involved POM (AgNPs/POM) nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. The synthesized POM was also characterized by elemental analysis and thermal analysis. The electrochemical performances of the POM, AgNPs, and AgNPs/POM composites were measured for charge/discharge specific capacities at different current rates in CR2032 coin-type cells. The prepared AgNPs/POM composite showed a high specific gravimetric capacity of about 1760 mAh g(-1) and long-term cycle stability.