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https://dspace.kmf.uz.ua/jspui/handle/123456789/963
2024-03-28T18:46:12ZComparative study of Ni(II) adsorption by pristine and oxidized multi-walled N-doped carbon nanotubes
https://dspace.kmf.uz.ua/jspui/handle/123456789/3439
Title: Comparative study of Ni(II) adsorption by pristine and oxidized multi-walled N-doped carbon nanotubes
Authors: Balog Renáta; Балог Рената; Maryna Manilo; Маніло Марина; Laszlo Vanyorek; Vanyorek László; Choma Zoltan; Csoma Zoltán; Чома Золтан; Sandor Barany; Bárány Sándor; Баран Олександр
Abstract: Abstract. The principles and mechanisms of adsorption of Ni(II) ions by well characterized pristine and oxidized Ndoped multi-walled carbon nanotubes (N-CNTs) are described and discussed. The samples were
synthesized by CCVD method using n-butylamine as the carbon source and Ni(NO3)2 + MgO as the
catalyst and purified by treatment with HCl. The surface functionalization was performed using oxidation
with a mixture of concentrated H2SO4 and HNO3. The morphology, nature and charge of surface groups
were characterized by HRTEM, XPS, FTIR and micro-electrophoresis methods. It has been shown that:
adsorption of Ni(II) reaches an equilibrium value within 20–30 min; the degree of extraction of nickel
ions from the solution increases with its dilution; adsorption of Ni(II) results in an insufficient decrease in
the suspension pH for pristine N-CNTs (0.5–0.6 pH unit) and considerable lowering of the pH for the
oxidized sample (up to 2.5 pH unit); the adsorption isotherms are described by the Langmuir equation;
the plateau amounts of adsorption (35–40 mg g 1
) are almost the same for both as-prepared and
oxidized samples; at pH 8 and higher a sharp increase in adsorption is observed which is caused by
nickel hydroxide precipitation. The spectroscopic, adsorption, electrophoretic and pH measurement data
testify that below pH 8 the major mechanism of adsorption by as-prepared N-CNTs is the donor–
acceptor interaction between the free electron pair of N atoms incorporated into the nanotube lattice
and vacant d-orbital of the adsorbing Ni(II) ions. For the oxidized N-CNTs ion-exchange processes with
a release of H+ play a decisive role.
Description: Contents: https://pubs.rsc.org/en/journals/journalissues/ra#!issueid=ra010006&type=current&issnonline=2046-2069; Editorial board: https://www.rsc.org/journals-books-databases/about-journals/rsc-advances/#boards-staff2020-01-01T00:00:00ZComparative study of Cu (II) adsorption by as-prepared and oxidized multi-walled N-doped carbon nanotubes
https://dspace.kmf.uz.ua/jspui/handle/123456789/3434
Title: Comparative study of Cu (II) adsorption by as-prepared and oxidized multi-walled N-doped carbon nanotubes
Authors: Simon Viktória; Шімон Вікторія; Maryna Manilo; Маніло Марина; Laszlo Vanyorek; Vanyorek László; Choma Zoltan; Чома Золтан; Csoma Zoltán; Sandor Barany; Баран Олександр; Bárány Sándor
Abstract: Abstract. The laws and mechanisms of adsorption of Cu(II) ions by well characterized and oxidized
N-doped multi-walled carbon nanotubes (N-CNTs) are discussed. The samples were synthesized by catalytic
chemical vapour deposition method using n-butylamine as a carbon source and their surface was functionalized by oxidation with mixture of concentrated H2SO4 and HNO3. The morphology, chemistry and charge
of surface groups were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy,
Fourier-transform infrared spectroscopy and micro-electrophoresis methods. It has been shown that:
adsorption of Cu(II) reached equilibrium value within 60 min; the degree of extraction of these ions from the
solution increased with its dilution; adsorption resulted in a moderate decrease in the suspension pH for asprepared N-CNTs (1.5 pH unit) and its considerable lowering for the oxidized sample (up to 2.5 pH unit);
the adsorption isotherms can be described by the Langmuir model and the plateau amounts of adsorption
(28–35 mg/g) were almost the same for both as-prepared and oxidized samples; at pH 6.5 and higher a sharp
increase in adsorption was observed which was attributed to hydroxides precipitation. The spectroscopic,
adsorption, electrophoretic and pH measurements data showed that below pH of hydroxide precipitation, the
major mechanism of adsorption by as-prepared N-CNTs is the donor-acceptor interaction between the free
electron pair of N atoms incorporated into nanotubes lattice and vacant d orbital of the adsorbing Cu(II) ions.
For the oxidized N-CNTs ion-exchange processes with a release of H+ ions play also a role.
Description: Contents: https://link.springer.com/journal/10595/volumes-and-issues/82-4; Editorial board: https://link.springer.com/journal/10595/editors2020-01-01T00:00:00ZA nagymuzsalyi aranybánya meddőinek hatása a felszín alatti vizekre
https://dspace.kmf.uz.ua/jspui/handle/123456789/3349
Title: A nagymuzsalyi aranybánya meddőinek hatása a felszín alatti vizekre
Authors: Vince Tímea; Вінце Тімео; Csoma Zoltán; Чома Золтан; Choma Zoltan; Molnár D. István; Молнар Д. Стефан; Stefan Molnar D.; Gönczy Sándor; Генці Шандор
Abstract: A bányászat számos káros környezeti hatással jár: a talaj eltávolítása, meddő anyag felhalmozása, a természetes élővilág eltávolítása, a felszíni lefolyási viszonyok megváltozása, tájképrombolás stb. A meddő felhalmozása révén, az oxigénnel érintkező kőzetanyag oxidációja megy végbe. A meddőn keresztüláramló és eközben savas oldattá váló csurgalékvizek igen agresszívek, amelyek nehézfémeket oldhatnak ki különböző fémvegyületekből (Kerényi 2003; Modoi et al. 2014). A szennyezőanyagok beszivároghatnak a talajvízbe, vagy lefolyás révén eljuthatnak a felszíni vizekbe, mindezek során felhalmozódhatnak, adszorbeálódhatnak, átalakulhatnak, oldódhatnak stb. Ha eljutnak valamelyik ivóvízbázisba komoly veszélyforrást jelentenek az ott lakók számára (Modoi et al. 2014; Sun et al. 2010). Igaz ugyan, hogy a nehézfémek egy része létfontosságú a növények, az állatok és az ember életfolyamataiban (pl., Co, Cu, Fe, Mn, Zn), hiszen természetes komponensként is jelen vannak a talajokban és a vizekben, más részük azonban nélkülözhető, sőt toxikus (pl. Pb, Cd, Hg). Ugyanakkor nagy koncentrációban az esszenciális mikroelemek is toxikus hatásúak lehetnek (Kádár 1991; Kátai 2011).; Abstract. The gold mine in Nagymuzsaly has been known for a long time for its gold resources. Mining is periodically restart in the area, as evidenced by a series of dumps accumulated around Beregszász and Nagymuzsaly but environmental issues were mostly not addressed. The aim of our study is to draw attention to the vulnerability of the population, the wildlife and the environment in the mining area. During the study, pH, electrical conductivity, nitrate content and some heavy metal concentrations (Cd, Co, Pb, Mn, Zn, Cu, Ni, Fe, Cr) were measured in the water samples of 11 dug wells. On the basis of the examined water samples, the heavy metal content of the groundwater was increased in some parts of the area. The Cd and Cr content exceeded the limit in some sampling points. The intermittent draining streams from the waste rock show a significant heavy metal enrichment.2019-01-01T00:00:00ZComparative Study of Ni(II) and Cu(II) Adsorption by As-Prepared and Oxidized Multi-Walled N-Doped Carbon Nanotubes
https://dspace.kmf.uz.ua/jspui/handle/123456789/3348
Title: Comparative Study of Ni(II) and Cu(II) Adsorption by As-Prepared and Oxidized Multi-Walled N-Doped Carbon Nanotubes
Authors: Balog Renáta; Балог Рената; Simon Viktória; Шімон Вікторія; Maryna Manilo; Маніло Марина; Laszlo Vanyorek; Vanyorek László; Csoma Zoltán; Чома Золтан; Choma Zoltan; Bárány Sándor; Баран Олександр; Sandor Barany
Abstract: Abstract. The laws and mechanisms of adsorption of Ni(II) and Cu(II) ions by wellcharacterized as-prepared and oxidized N-doped multi-walled carbon nanotubes (N-CNTs) are described and discussed. The samples are synthesized
by catalytic chemical vapour deposition method using n-butylamine as
carbon source and Ni(NO3
)2 MgO as catalyst and purified by treatment
with HCl. The surface functionalization is performed using oxidation with
mixture of concentrated H2SO4 and HNO3
. As shown, adsorption of Ni(II)
and Cu(II) reaches equilibrium value within 20–30 min; adsorption results
in a moderate decrease in the suspension pH for pristine N-CNTs (1.0–1.5
pH unit) and a considerable lowering the pH for oxidized sample (up to
2.5 pH unit); the adsorption isotherms are described by the Langmuir
equation; the plateau amounts of adsorption (25–30 mg/g for Cu and 35–
40 mg/g for Ni) are almost the same for both as-prepared and oxidized
samples; at pH 8.0 and higher for Ni and pH 6.5 and higher for Cu ions,
a sharp increase in adsorption is observed that is caused by the hydroxides’ precipitation. The spectroscopic, adsorption, electrophoretic and pH
measurements’ data testify that below pH of hydroxide precipitation, the
major mechanism of adsorption by as-prepared N-CNTs is the donor–
acceptor interaction between the free electron pair of N atoms incorporated into nanotubes’ lattice and vacant d-orbital of the adsorbing Ni(II) or Cu(II) ions. For the oxidized N-CNTs, ion-exchange processes with a
release of H may play minor role.; Резюме. В роботі розглянуто закони та механізми адсорбції йонів Ni(II) та Cu(II) охарактеризованими вихідними та окисненими N-леґованими багатостінними вуглецевими нанорурками (N-CNT). Зразки синтезували методою каталітичного хемічного осадження пари n-бутиламіну як джерела Карбону та Ni(NO3 )2 + MgO як каталізатора з подальшою очисткою їх HCl. Функціоналізацію поверхні N-CNT проводили за допомогою окиснення сумішшю концентрованих H2 SO4 та HNO3 . Було показано, що: адсорбція йонів Ni(II) та Cu(II) досягає рівноважного значення протягом 20–30 хв.; адсорбція приводить до помірного зменшення рН суспензії для вихідних (1,0–1,5 одиниці pH) та значного пониження рН (до 2,5 одиниць рН) для окиснених N-CNT-зразків; ізотерми адсорбції описуються Ленґмюровим рівнянням; положення плато адсорбції (25-30 мг/г для Cu та 35–40 мг/г для Ni) майже однакове як для вихідних, так і для окиснених зразків; при рН ≥ 8,0 для йонів Ni та рН ≥ 6,5 для йонів Cu спостерігається різке збільшення величини адсорбції за рахунок осадження гідроксидів.2020-01-01T00:00:00Z