Библиотека института физики им. Л.В. Киренского СО РАН

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Труды сотрудников ИФ СО РАН

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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kirillov V. L., Balaev D. A., Semenov S. V., Shaikhutdinov K. A., Martyanov O. N.
Заглавие : Size control in the formation of magnetite nanoparticles in the presence of citrate ions
Коллективы : Siberian Branch of the Russian Academy of Sciences
Место публикации : Mater. Chem. Phys.: Elsevier Science, 2014. - Vol. 145, Is. 1-2. - P.75-81. - ISSN 0254-0584, DOI 10.1016/j.matchemphys.2014.01.036. - ISSN 1879-3312
Примечания : Cited References: 46. - This work was supported by the Interdisciplinary Integration Project no. 45 of the Siberian Branch of the Russian Academy of Sciences for 2012-2014.
Предметные рубрики: OLEIC-ACID
CATALYST
HYPERTHERMIA
PARTICLES
OXIDATION
REMOVAL
CO
Ключевые слова (''Своб.индексиров.''): magnetic materials--magnetic properties--precipitation--electron paramagnetic resonance
Аннотация: A one-pot synthesis method for the controllable growth of magnetite nanoparticles directly during the process of co-precipitation using citrate ions was developed. The effects of the concentration of citrate ions and the solution pH on the characteristics of magnetite particles with sizes in the range of 4-10 nm synthesized by the method of co-precipitation were studied. The results showed that the specified concentration of citrate ions allowed the preparation of magnetite particles with a definite size that exhibited superparamagnetic behaviour in a particular temperature range. As the concentration ratio of citrate to iron ions was increased from 0 to 0.11, the average size of the prepared magnetite particles decreased from 10.5 to 4.4 nm. As a result, the superparamagnetic blocking temperature decreased from 300 to 20 K, the saturation magnetisation decreased from 50 to 20 emu g(-1), and the average magnetic moment decreased from 8000 mu(B) to 340 mu(B) (at T = 300 K). The obtained experimental data proved that the size effects of the magnetite nanoparticles can be attributed to the capping of the magnetite surface by adsorbed citrate ions. Thus, the suggested approach allows magnetite nanoparticles to be prepared with an optimum particle size around superparamagnetic threshold that prevents their irreversible agglomeration and simultaneously allows them to be removed from a solution at an acceptable rate. (C) 2014 Elsevier B.V. All rights reserved.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Potylitsyna, Arina R., Mishakov, Ilya, V, Bauman, Yury, I, Kibis, Lidia S., Shubin, Yury, V, Volochaev M. N., Melgunov, Maxim S., Vedyagin, Aleksey A.
Заглавие : Metal dusting as a key route to produce functionalized carbon nanofibers
Коллективы : Ministry of Science and Higher Education of the Russian Federation [AAAA-A21-121011390054-1, 0239-2021-0010, 121031700315-2]
Место публикации : React. Kinet. Mech. Catal. - 2022. - Vol. 135, Is. 3. - P.1387-1404. - ISSN 1878-5190, DOI 10.1007/s11144-022-02169-y. - ISSN 1878-5204(eISSN)
Примечания : Cited References: 65. - This work was supported by the Ministry of Science and Higher Education of the Russian Federation (Project numbers AAAA-A21-121011390054-1 (ID: 0239-2021-0010) and 121031700315-2)
Предметные рубрики: CHLORINATED HYDROCARBONS
NI-CU
DECOMPOSITION
NANOTUBES
CATALYST
Аннотация: The present paper reports a new method of producing N-doped carbon nanofibers via metal dusting of a ternary NiMoW alloy in the atmosphere containing C2HCl3 and CH3CN vapors at 600 °C. The initial alloy was prepared by a co-precipitation technique. The carbon deposition was monitored gravimetrically. The early stages of the metal dusting process were studied in detail using scanning and transmission electron microscopies. It was established that the rapid disintegration of the microdispersed NiMoW alloy with the formation of nanosized particles catalyzing the growth of carbon filaments occurs within the first 5 min of the reaction. The presence of C2HCl3 vapors in the reaction medium was shown to be the urgent condition to provide efficient metal dusting. The effect of the CH3CN concentration in the trichloroethylene-containing reaction mixture on the carbon deposition is investigated. As observed, the CH3CN content noticeable affects the carbon yield (after 2 h of reaction). The dome-shaped dependence of carbon yield reaches its maximal value of ~ 200 g/g(cat) at a CH3CN concentration of 33 vol%. According to X-ray photoelectron spectroscopy, the obtained carbon filaments are functionalized with Cl (0.1–1.2 wt%), O (3–6 wt%), and N (0.5–1.3 wt%). The prepared carbon filaments possess a segmented secondary structure, which is typical for carbon nanomaterials derived via catalytic decomposition of chlorine-substituted hydrocarbons. Low-temperature nitrogen adsorption measurement revealed that the specific surface area of the N-containing samples varies in a range from 370 to 550 m2/g.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kononova O.N., Melnikov A.M., Borisova T.V., Krylov A. S.
Заглавие : Simultaneous ion exchange recovery of platinum and rhodium from chloride solutions
Место публикации : Hydrometallurgy. - 2011. - Vol. 105, Is. 3-4. - P.341-349. - JAN. - ISSN 0304-386X, DOI 10.1016/j.hydromet.2010.11.009
Примечания : Cited Reference Count: 46
Предметные рубрики: GROUP-METALS PGM
SEPARATION
CATALYST
ANION
ADSORPTION
EXTRACTION
CHEMISTRY
RESIN
Ключевые слова (''Своб.индексиров.''): platinum--rhodium--sorption--anion exchangers--chloride solutions--anion exchangers--chloride solutions--platinum--rhodium--sorption--ammonium thiocyanate--anion exchangers--basic parameters--chemical structure--chloride solutions--diffusion coefficients--distribution coefficient--exchange capacities--kinetic properties--noble metals--purolite--rhodium chloride--separation factors--sorption ability--work focus--ammonium compounds--chlorine compounds--desorption--hydrochloric acid--ion exchange--ion exchange resins--ions--platinum--platinum compounds--potassium hydroxide--precious metals--recovery--rhodium--sulfuric acid--thioureas--urea--rhodium compounds
Аннотация: This work focuses on the sorption recovery of platinum (II, IV) and rhodium (III) simultaneously present in chloride solutions, freshly prepared and stored over 3 months, on commercial anion exchangers with different physical and chemical structure. The sorption was carried out from solutions with 0.001-4.0 mol/L HCl. The initial platinum and rhodium concentrations in contacting solutions were 0.25-2.5 mmol/L Sorption and kinetic properties of the chosen anion exchangers were investigated and the basic parameters of exchange capacity, recovery, distribution coefficients, separation factors, process rate, diffusion coefficients and half-exchange times were calculated. It is shown that anion exchangers investigated possess high sorption ability to platinum and rhodium chloride complexes, which does not deteriorate in case of stored solutions. Desorption of platinum and rhodium from the resins investigated was carried out with hydrochloric acid (2 mol/L), thiourea (1 mol/L) in sulfuric acid (2 mol/L) or in potassium hydroxide (2 mol/L) as well as by ammonium thiocyanate (2 mol/L). It was shown that complete separation of platinum and rhodium can be carried out with 2 mol/L HCl on anion exchanger Purolite S 985, whereas 2 mol/L NH(4)SCN as an elution agent leads to complete separation of noble metals on anion exchangers Purolite S 985, Purolite A 500 and AM-2B. (C) 2010 Elsevier B.V. All rights reserved.
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