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    Evaluation of the performance of calix[8]arene derivatives as liquid phase extraction material for the removal of azo dyes
    (ELSEVIER SCIENCE BV, 2008) Gungor, Omer; Yilmaz, Aydan; Memon, Shahabuddin; Yimaz, Mustafa
    This pit per presents a study on the removal of azo dyes (Reactive Black 5, Trapaeolin 000, Methyl Orange and Direct Violet 51) with calix[n]arene derivatives from aqueous solution into the organic phase in order to explore the potential use of calixarenes as low-cost efficient extractants for wastewater dye removal. The carboxylic acid derivative of calix[8]arene shows highest affinity towards the azo dyes. The influence of NaCl (present in the solution) on extraction process was also Studied. The extent of the dye removal increased with the addition of NaCl. The proposed extraction mechanism involves several kinds of interactions: electrostatic repulsion between carboxylic acid groups of calix[8]arenes and sulfonate groups of azo dyes, hydrogen bonding and formation of an inclusion complex due to three dimensional cavity type calix[n]arene molecules through host-guest interactions. (C) 2008 Elsevier B.V. All rights reserved.
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    Preparation, characterization of cellulose-grafted with calix[4]arene polymers for the adsorption of heavy metals and dichromate anions
    (ELSEVIER SCIENCE BV, 2007) Tabakci, Mustafa; Erdemir, Serkan; Yimaz, Mustafa
    In this paper, the adsorbents were prepared from cellulose-grafted with calix[4]arene polymers (CGC[4]P-1 and CGC[4]P-2) and their sorption properties studied. The polymers were characterized by Fourier transform infrared spectroscopy, elemental analysis, thermal gravimetric analysis and scanning electron microscopy. They were then used to evaluate the sorption properties of some heavy metal cations (CO2+, Ni2+, cu(2+), Cd2+, Hg2+ and Pb2+) and dichromate anions (Cr-2,O-7(2-)/HCr,O-7(-)). Results showed that CGC[4]P-2 was a good sorbent for heavy metal cations while CGC[4]P-1 was ineffective. In the studies of dichromate anion sorption, it was observed that CGC[4]P-2 was a more highly effective sorbent at pH 1.5 than was CGC[4]P-1. (c) 2007 Elsevier B.V. All rights reserved.
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    Synthesis and dichromate anion extraction ability of p-tert-butylcalix[4]arene diamide derivatives with different binding sites
    (PERGAMON-ELSEVIER SCIENCE LTD, 2007) Yilmaz, Aydan; Tabakci, Begum; Akceylan, Ezgi; Yimaz, Mustafa
    The article describes the synthesis and evaluation of the dichromate anion (Cr2O72-/HCr2O7-) extraction properties of p-tert- butylcalix[4]arene diamide derivatives (5-7) containing different binding sites. Among these compounds, 6 and 7 have been synthesized via aminolysis in a toluene-methanol solvent system with 3-aminomethylpyridine and 3,6-dioxa-1,8-diamino octane, respectively. On the other hand, compound 5 has been synthesized via an acid chloride method due to its inefficiency under aminolysis. The extraction properties of these diamides toward dichromate anions are studied by liquid-liquid extraction. The results show that p-tert-butylcalix[4]arene diamide derivative 7 exhibited a much higher affinity toward dichromate anions than that of 6 due to its special structure, while 5 was an ineffective ligand for these anions. (c) 2007 Elsevier Ltd. All rights reserved.
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    Synthesis and evaluation of the Cr(VI) extraction ability of amino/nitrile calix[4]arenes immobilized onto a polymeric backbone
    (ELSEVIER SCIENCE BV, 2006) Memon, Shahabuddin; Tabakci, Mustafa; Roundhill, D. Max; Yimaz, Mustafa
    Three new calix[4]arene based polymeric resins (6, 7 and 8) have been synthesized via nucleophilic substitution reactions involving 5,11,17,23-tetrakis-[(N,N-dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 3, and 5,11,17,23-tetracyanomethyl-25,26,27,28-tetrahydroxycalix[4]arene 4 as precursors with a Merrifield resin. The extraction studies were made by using liquid-liquid extraction, solid-liquid batchwise and packed-column sorption procedures, and effect of different anion to extraction of dichromate anion was examined by using NO3-, Cl-, SO42- and their mixtures. The experimental tal results showed that these calix[4]arene based polymeric resins have high extraction abilities towards Na2Cr2O7 as compared to their monomeric precursors, and also dichromate anion was extracted in high ratios even in presence of different anions. (c) 2006 Elsevier B.V. All rights reserved.
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    Use of beta-cyclodextrin and starch based polymers for sorption of Congo red from aqueous solutions
    (ELSEVIER, 2007) Ozmen, Elif Yimaz; Yimaz, Mustafa
    Two starch-based and a P-cyclodextrin (beta-CD)-based polymers were synthesized using 4,4'-methylene-bis-phenyldiisocyanate (MDI) or hexamethylenediisocyanate (HMDI) as a cross linking agent in dry dimethylformamide and used as a sorbent for the removal of Congo red from aqueous solutions. The cross-linked polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric and differential scanning calorimetric analysis. The dye adsorption experiments were carried out by using batch and recycling column procedure. The effects of initial pH (pH(0)). the contact time and the initial dye concentration were changed to obtain the best experimental conditions. The pH(0) of the dye solution strongly affected the chemistry of both the dye molecules and polymer 3 in an aqueous solution. The effective pH(0) was 7.0 for adsorption on polymer 3. The equilibrium adsorption data were interpreted using Langmuir and Freundlich models. The adsorption of Congo red was better represented by the Freundlich equation. (C) 2007 Elsevier B.V. All rights reserved.