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EPR Study of Dealuminated HY Zeolite and Silica Containing Cu-Mn-Zn Spinels: The Effect of Support

100%

Decyk P., Więckowski A., Najder-Kozdrowska L., Bilkova I., Ziółek M.

Acta Physica Polonica A

2017

vol. 132

issue 1

38-44

A mixture of antiferromagnetic Cu_{1.4}Mn_{1.6}O₄ and Cu_{0.5}Zn_{0.5}Mn₂O₄ or/and ZnMn₂O₄ spinels was prepared. Dealuminated HY zeolite and silica were doped by these Cu-Mn-Zn spinels. The materials were investigated by X-ray diffraction, the Fourier transform infrared spectroscopy and EPR spectroscopy. Additionally, all the samples were tested for their activity for isopropyl alcohol dehydration/dehydrogenation. Three EPR signals were observed for Cu-Mn-Zn/dealuminated HY and Cu-Mn-Zn/SiO₂ samples at 293 K. In contrast to the spectra recorded at 293 K, only one broad line attributed to Cu-Mn-Zn spinels was visible at 77 K. The EPR signal from pure Cu-Mn-Zn spinels consists only of a single broad line when recorded at 293 K, whereas at 77 K the line is narrower. For all samples subjected to evacuation at high vacuum up to 573 K, the Cu-Mn-Zn spinels were stable. The evacuation at 673 K resulted in a rapid lowering of the intensity of EPR spectrum.

Sorption of Neodymium and Gadolinium on Transcarpathian Clinoptilolite

100%

Vasylechko V., Stechynska E., Stashkiv O., Gryshchouk G., Patsay I.

Acta Physica Polonica A

2018

vol. 133

issue 4

794-797

The sorption properties of Transcarpathian clinoptilolite towards Nd(III) and Gd(III) under dynamic condition have been studied. Nd(III) was sorbed with the best efficiency on the uncalcined clinoptilolite samples from the solutions at pH 6.5. Clinoptilolite samples that were previously calcined at 250°C exhibit the maximal sorption capacity towards Gd(III) from the solutions at pH 9.5. Nd(III) and Gd(III) sorption on clinoptilolite mechanisms are different: Nd(III) is sorbed according to the ion-exchange mechanism, and the sorption of Gd(III) is carried out mainly by means of the adsorption of soluble hydrolyzed forms of Gd(III) on the zeolite surface. The differences in sorption mechanisms of these lanthanides give an opportunity to separate Nd(III) and Gd(III) from the solutions at pH 9.5. The maximal sorption capacity of the clinoptilolite regarding Nd(III) and Gd(III) at the optimal conditions was found to be 1810 and 6500 μg/g. The best desorbent of Nd from the clinoptilolite is 7 M HNO₃ solution. The best desorbent of Gd is 1 M solution of KCl acidified to pH 2.6, which provides a 100% withdrawal of Gd from the zeolite matrix. Transcarpathian clinoptilolite is proposed as a sorbent for the preconcentration of trace amounts of Nd(III) and Gd(III) from aqueous solutions in a solid phase extraction mode.

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2 Acta Physica Polonica A

1 2018

1 2017

1 Bilkova I.

1 Decyk P.

1 Gryshchouk G.

1 Najder-Kozdrowska L.

1 Patsay I.

1 Stashkiv O.

1 Stechynska E.

1 Vasylechko V.

1 Więckowski A.

1 Ziółek M.

Search results

EPR Study of Dealuminated HY Zeolite and Silica Containing Cu-Mn-Zn Spinels: The Effect of Support

Sorption of Neodymium and Gadolinium on Transcarpathian Clinoptilolite