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Dye removal using keggin polyoxometalates assisted ultrafi ltration: characterization and UV visible study

Kahloul Malak, Chekir Jalila, Hafiane Amor

Archives of Environmental Protection

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2019

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Vol. 45, no. 4

30--39

EN

To improve dye retention, there is a concurrent interest in the development and optimization of an alternative and promising method for the dye recovery in aqueous solutions. In this regard, considerable attention was paid to the polyoxometalates (POMs) assisted ultrafiltration (POMAUF). The aim of the present study is to eliminate toluidine blue (TB) dye by ultrafiltration membrane using keggin polyoxometalates (POMs) as complexing agents. In the first step, the keggin polyoxometalates K3[PW12O40]∙6H2O (PW12) and K7 [PW11O39]∙14H2O (PW11) were prepared. Then, the obtained powders were characterized by X-ray diffraction and infrared spectroscopies. Afterwards, the removal of toluidine blue (TB) using polyoxometalates assisted ultrafiltration (POMAUF) was studied. Factors affecting the retention of dye and permeate flux such as transmembrane pressure, operating time, polyoxometalates concentration, ionic strength, surfactant and pH were investigated. All results of both compounds have been presented and discussed. The results reveal that the addition of POMs leads to an increase in dye retention from 11 to 95% for the PW12 and to 98% for the PW11. The results of this work have thus suggested the promising enhancement of ultrafiltration membrane selectivity for the dye removal using new complexing agents such as POMs in place of polyelectrolytes and surfactants.

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Zastosowanie polioksometalanu Na12[WZn3(H2O)2][ZnW9O34)2] jako katalizatora reakcji utleniania alkoholi w polu promieniowania mikrofalowego

Kasprzyk W., Galica M., Bednarz S., Bogdał D.

Czasopismo Techniczne. Chemia

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2012

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R. 109, z. 2-Ch

65--71

PL

W artykule przedstawiono wyniki reakcji utleniania alkoholi katalizowanych przez Na12[WZn3(H2O)2][ZnW9O34)2] (ZnPOM). Reakcje te przeprowadzono w mikrofalowym reaktorze ciśnieniowym stosując acetonitryl jako rozpuszczalnik oraz 30% nadtlenek wodoru jako utleniacz. Z przeprowadzonych badań wynika, że alkohole I-rzędowe utleniają się do odpowiednich kwasów, alkohole II-rzędowe do ketonów, w przypadku dioli okazało się, że II-rzędowe grupy –OH utleniają się w pierwszej kolejności.

EN

In this paper the results of oxidation of alcohols under microwave irradiation using Na12[WZn3(H2O)2][ZnW9O34)2] (ZnPOM) as a catalyst was shown. These reactions were conducted in microwave high-pressure reactor using acetonitryl as organic solvent and 30% hydrogen peroxide as oxidant. Under reaction conditions primary alcohols were oxidized to appropriate acids, secondary alcohols were oxidized to ketones. In case of diols it was found that secondary –OH groups were oxidized in the first instance.

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Synthesis and Characterization of Two Novel Inorganic-Organic Hybrid Materials Based on Polyoxotungstoborate: [L-C2H5NO2-H]3[H2BW12O40]ź5H2O and [CH4N2O-H]2[H3BW12O40]ź5H2O (C2H5NO2 = Glycine; CH4N2O = Urea)

Alizadeh M. H., Eshtiagh-Hosseini H., Mirzaei M., Hosseini-Nejad M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 9

1583-1589

EN

Two novel hy drated in or ganic-or ganic hy brids, namely [L-C2H5NO2-H]3[H2BW12O40]ź ź5H2O (1) and [CH4N2O-H]2[H3BW12O40]ź5H2O (2), where C2H5NO2 and CH4N2O are glycine and urea, respectively, have been synthesized and characterized by CHN microanalysis, IR, UV, and 1H NMR spectroscopies. According to the obtained results, molecular structure of 1 consists of tungstoborate anions linked to glycinium cations via van der Waals interactions and hydrogen bonding. Three [L-C2H5NO2-H]+ moieties encompass each [H2BW12O40]3- and, almost certainly, the same is true for 2. The O atoms of polyoxometalates and water, as well as the N atoms of L-glycine and urea are in volved in hydrogen bonding. Characteristic UV bands of the Keggin anion, alfa-H5[BW12O40]ź ź19H2O, are observed at 257 nm, as would be expected.

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Thermal properties of the molybdenum - oxide based {Mo154} giant wheel type cluster with methanol ligands bonded to its surface

Bielański A., Małecka-Lubańska A., Krickemeyer E., Bögge H., Schmidtmann M., Müller A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2001

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Vol. 49, No. 3

245-254

EN

The thermal behaviour of the giant molybdenum ring cluster compound formula - containing H2O ligands partly substituted by methanol molecules - was studied using TG, DTG and DTA analyses simultaneously, and mass spectromet-ric analysis of the decomposition products. Methanol is released from the sample quite rapidly even at room temperature (and even before the experiments start) but small traces of methanol are still present which we tried to use for characterising the different stages of giant ring transformation. The initial rapid loss of mass of the sample was accompanied by the DTA and DTG peak at 75°C. A small DTA endothermic peak at 165°C was assigned to an MS maximum indicating the increased emission of methanol and formaldehyde. Double exothermic peaks at 352 and 366° C corresponded to the loss of water formed from the abundant OH groups. Simultaneously, peaks indicating trace emission of formaldehyde, methanol, carbon dioxide as well as traces of hydrocarbons containing 2-4 carbon atoms per molecule were registered mass spectrometrically. The exothermic effect was attributed to a kind of "recrystallisation" process of the completely dehydrated product.