Temat: methods of modification - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Modification of Salix americana willow bark for removal of heavy metal ions from aqueous solutions
Autorzy:: Rypińska, Iwona
Biegańska, Marta
Powiązania:: https://bibliotekanauki.pl/articles/779386.pdf
Data publikacji:: 2014
Wydawca:: Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:: waste
adsorption
heavy metals
willow bark
methods of modification
Opis:: Salix americana willow bark is a waste arising in the process of wicker decortication that so far has not found Any practical application. The bark can adsorb metal ions, because in its composition among others are phenolic groups which may be involved in the removal of metal ions from water solutions. The results of sorption of copper(II) and zinc(II) on modifi ed willow bark of Salix americana were presented. The bark was modifi ed with nitric and sulfuric acids at concentrations ranging from 5 to 15%. The best adsorption results were obtained using 15% nitric acid for modifi cation. Adsorption of metal ions from aqueous solutions at concentrations raging from 20 to 100 mg/dm3 was studied. It was found that an increase in the initial concentration of copper(II) and zinc(II) resulted in an increase in their adsorption on the modifi ed cortex.
Źródło:: Polish Journal of Chemical Technology; 2014, 16, 4; 41-44
1509-8117
1899-4741
Pojawia się w:: Polish Journal of Chemical Technology
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Gold catalysts supported on zeolites
Katalizatory złotowe osadzone na zeolitach
Autorzy:: Walkowiak, Adrian
Powiązania:: https://bibliotekanauki.pl/articles/2057912.pdf
Data publikacji:: 2021
Wydawca:: Polskie Towarzystwo Chemiczne
Tematy:: heterogeniczne katalizatory złotowe
nanocząstki złota
zeolity
metody modyfikacji zeolitów złotem
zastosowanie zeolitów modyfikowanych złotem
proces katalityczny
heterogeneous gold catalysts
gold nanoparticles
zeolites
methods of zeolites modification with gold
application of gold-modified zeolites
catalytic process
Opis:: Heterogeneous gold catalysis is a relatively young but dynamically developing field of chemistry. At the end of the 1980s, Masatake Haruta and Graham Hutchings provided experimental evidence of high activity of supported gold catalysts in CO oxidation and acetylene hydrochlorination. Thus, these two researchers challenged the prevailing chemists’ belief that gold is almost completely chemically inert and catalytically inactive. Since then, gold catalysis has been constantly in the centre of attention of a wide array of scientists from around the world. However, there are still many questions about the nature of catalysts containing this noble metal, which inspires in-depth research in this field. From among various potential supports for gold heterogeneous catalysts, zeolites have drawn much attention thanks to several unique properties of this group of materials, among which the most important are high thermal stability and the presence of a system of pores of strictly defined sizes. Zeolites have extremely large surface area, which is desirable to obtain high dispersion of the active phase. The article provides a concise overview of the methods of gold nanoparticles deposition on zeolitic supports and catalytic applications of such materials. The first chapter sheds light on the properties of bulk and nano-sized Au and depicts the background of gold catalysis development. In the following part, a brief description of zeolites and their properties is delivered. The third chapter is devoted entirely to the description of several preparation methods of zeolite-supported gold catalysts and their applications in different catalytic processes. The following post-synthetic methods of zeolite modification with gold are described: impregnation, ion exchange, deposition-reduction, chemical vapour deposition, and grafting. The most important advantages and disadvantages of each method are summarized. The article concludes with a résumé of literature reports concerning the use of zeolitesupported gold catalysts in various processes. Special attention was paid to selective oxidation of alcohols and biomass-derived chemicals (e.g. glucose).
Źródło:: Wiadomości Chemiczne; 2021, 75, 11-12; 1259--1293
0043-5104
2300-0295
Pojawia się w:: Wiadomości Chemiczne
Dostawca treści:: Biblioteka Nauki

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