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Koviljka A. Asanovic,Dragana D. Cerovic,Mirjana M. Kostic,Tatjana V. Mihailovic,Aleksandra M. Ivanovska 한국섬유공학회 2020 Fibers and polymers Vol.21 No.10
In this work, the volume electrical resistivity and dielectric loss tangent of viscose/polypropylene multipurposenonwoven fabrics were examined. According to the obtained results, the changes in the volume electrical resistivity dependon the applied chemical bonding agent, viscose fiber content, moisture content, fabric thickness, fabric weight, and relativeair humidity. Based on the volume electrical resistivity hysteresis, the portion of sorbed moisture retained in the material afterdesorption, as well as the portion of moisture removed from the material during desorption, were determined. Furthermore,the dielectric loss tangent measured at the frequency range between 30 Hz and 140 kHz, for the samples exposed to differentrelative air humidity (40 % and 80 %) and wet samples, is dependent on the chemical bonding agent, viscose fiber content,moisture content, as well as frequency of the external electric field. The dielectric loss tangent measured at 80 % relative airhumidity showed a peak at about 100 Hz, while for the wet samples, the peak was observed in the frequency range between30 and 140 kHz. In a wet state, the dielectric loss tangent is primarily influenced by the water molecules present in thesample.
Asanova, Tatyana I.,Asanov, Igor P.,Kim, Min-Gyu,Gorgoi, Mihaela,Sottmann, Jonas,Korenev, Sergey V.,Yusenko, Kirill V. The Royal Society of Chemistry 2018 New journal of chemistry Vol.42 No.7
<P>A new approach based on a combination of synchrotron radiation techniques, such as X-ray absorption fine structure (XAFS), X-ray photoelectron spectroscopy (XPS), hard X-ray photoelectron spectroscopy (HAXPES), and powder X-ray diffraction (PXRD), has been applied to <I>in situ</I> study the processes of thermal decomposition of inorganic compounds and the formation of bimetallic nanoalloys. As an example, a double complex salt, [Pd(NH3)4][PtCl6], was selected because of (i) its sufficiently complicated structure and previous studies conducted <I>via</I> thermal analysis, <I>ex situ</I> PXRD and XPS, and (ii) its use as a prospective single-source precursor for the preparation of bimetallic (PdPt) nanoparticles or nanoalloys. The differences between the mechanisms based on <I>ex situ</I> and <I>in situ</I> data have been discussed for the first time. It has been found that the first step of thermal decomposition is related to the formation of crystalline [Pd(NH3)2Cl2][Pt(NH3)2Cl4]. Further decomposition results in the formation of {PdCl2}, {PtCl2}, and (NH4)2[PtCl6] in the second step. In the final step, the intermediates are completely reduced, and a bimetallic nanoalloy is formed. The different means of Pd and Pt reduction on the surface and in the bulk result in the formation of a disordered nanoalloy with possible monometallic inclusions. Further heating orders the nanoalloy that is accompanied by a decrease in the positive charge on Pt.</P>
Min, Yo-Sep,Bae, Eun Ju,Asanov, Igor P,Kim, Un Jeong,Park, Wanjun IOP Pub 2007 Nanotechnology Vol.18 No.28
<P>Nitrogen-doped single-walled carbon nanotubes (N-SWNTs) are directly grown on SiO<SUB>2</SUB>/Si substrates at 450 °C with methane and ammonia gases by water-plasma chemical vapour deposition. The strongest radial breathing mode peak in Raman spectra of the grown N-SWNTs, probed with a 633 nm laser excitation, was assigned to (7, 5) semiconducting nanotubes with a diameter of 0.83 nm. As the doped nitrogen content increases, the D-band to G-band ratio in Raman spectra, indicating the imperfection of nanotubes, gradually increases and saturates at around 4%. X-ray photoelectron spectroscopy shows that nitrogen atoms are doped with a pyridine-like configuration in the N-SWNTs.</P>
Martynova, S. A.,Plyusnin, P. E.,Asanova, T. I.,Asanov, I. P.,Pishchur, D. P.,Korenev, S. V.,Kosheev, S. V.,Floquet, S.,Cadot, E.,Yusenko, K. V. The Royal Society of Chemistry 2018 NEW JOURNAL OF CHEMISTRY Vol.42 No.3
<P>[M(NH3)5Cl][IrCl6], M = Co, Cr, Ru, Rh, and Ir, were proposed as single-source precursors for bimetallic alloys. Their thermal decomposition in inert and reductive atmospheres below 700 °C results in the formation of nanostructured porous Ir0.5M0.5 alloys. Salts decompose with a significant exothermal effect during the first stage of their thermal breakdown in an inert atmosphere above 200 °C. The exothermal effect gradually decreases in the series: [Co(NH3)5Cl][IrCl6] (1) > [Cr(NH3)5Cl][IrCl6] (2) > [Ru(NH3)5Cl][IrCl6] (3) > [Rh(NH3)5Cl][IrCl6] (4); [Ir(NH3)5Cl][IrCl6] (5) does not exhibit any thermal effects and decomposes at much higher temperatures. To shed light on their thermal decomposition and the nature of the exothermal effect, DSC-EGA, <I>in situ</I> and <I>ex situ</I> IR, Raman, XPS and XAFS studies were performed. A combination of complementary techniques suggests a simultaneous ligand exchange and a reduction of central atoms as key processes. In [Co(NH3)5Cl][IrCl6], Co(iii) and Ir(iv) simultaneously oxidise coordinated ammonia, which can be detected due to a significant exothermal effect and the presence of Co(ii) and Ir(iii) in the intermediate product. The appearance of Ir-N frequencies demonstrates a ligand exchange between cations and the [IrCl6]<SUP>2−</SUP> anion. Salts with Cr(iii), Ru(iii), and Rh(iii) show a much lower exothermal effect due to the stability of their oxidation states. Salts with Rh(iii) and Ir(iii) demonstrate a high thermal stability and a low tendency for ligand exchange as well as decomposition with exothermal effects.</P>
Waste Jute Fabric as a Biosorbent for Heavy Metal Ions from Aqueous Solution
A. Ivanovska,B. Dojcinovic,S. Maletic,L. Pavun,K. Asanovic,M. Kostic 한국섬유공학회 2020 Fibers and polymers Vol.21 No.9
The influence of the chemical composition on the biosorption potential of waste jute fabric for Ni2+, Cu2+, and Zn2+was investigated. The raw jute fabric was treated with sodium hydroxide or sodium chlorite to selectively removehemicelluloses and lignin, respectively. All jute fabrics were characterized by determination of their chemical composition aswell as functional group content. The effects of solution pH, contact time, and initial metal ion concentration on thebiosorption from monometallic and polymetallic solution by jute fabrics were investigated. The maximum biosorptioncapacity for all heavy metal ions was observed at pH 5.5. Concerning the contact time, the raw jute fabric shows more than72 % of the total uptake capacity of Ni2+, Cu2+, and Zn2+ within 1 h, while the jute fabrics with lower hemicelluloses andlignin content show between 72-85 % of the total uptake capacity within 3 h. Increased initial metal ion concentration from10 to 20 mg/l in monometallic solution caused an increase in the total uptake capacity of jute fabrics with lowerhemicelluloses and lignin content for 47-69 % (Ni2+), 42-63 % (Cu2+), and 22-37 % (Zn2+). The biosorption capacity of alkalitreated jute fabrics was affected by the changes in the total amount of carboxyl and aldehyde groups that accompany thehemicelluloses removal. In the case of the oxidative treatment, the biosorption capacity was affected by the lignin content aswell as the amount of introduced carboxyl groups. The best biosorption performance possesses jute fabric with 63.2 % lowerlignin content as well as 81.1 % higher amount of carboxyl groups; biosorption capacity toward Ni2+, Cu2+, and Zn2+ inmonometallic solution is about 2.4; 2.2 and 3.5 times higher compared to the raw jute fabric, respectively. All jute fabricsexhibited the same affinity order (which is independent on the initial metal ion concentrations) toward heavy metal ions: Ni2+> Cu2+ > Zn2+ in the case of competitive biosorption. An increase in the initial metal ion concentration for two times in thepolymetallic solution caused about a 35-59 % increase in the total uptake capacity of Ni2+, while the total uptake capacities ofCu2+ and Zn2+ increased for 19-38 % and 18-65 %, respectively.