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Wyszukujesz frazę "thiourea" wg kryterium: Temat

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    Wyświetlanie 1-7 z 7
    Tytuł:
    Dissolution of gold with cyanide replacingreagents
    Autorzy:
    Aromaa, J.
    Rintala, L.
    Kahari, M.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/109410.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold leaching
    ammonium thiosulfate
    chloride
    thiourea
    thiocyanate
    Opis:
    Cyanide is used in the leaching phase of hydrometallurgical recovery of gold. The toxicity and environmental risks have created a need for safer alternatives. There is a vast amount of information about gold extraction and a selection has been collected and formalized to be used in a decision support tool. The tool Auric Advisor uses case-based reasoning (CBR) to provide process alternatives for the user queries. The aim of this paper is to study leaching of gold with cyanide replacing alternatives such as ammonium thiosulfate, chloride-hypochlorite, thiourea and thiocyanate to provide new cases for the tool. The behaviour of gold was examined with electrochemical tests and weight loss measurements a using quartz crystal microbalance (QCM) were used to determine the dissolution rate. Based on literature, the dissolution rate determined for cyanide solution was 2.5 mgcm-2h-1. Based on polarisation experiments and potential measurements, the ammonium thiosulfate system with cupric ion as oxidant was estimated to dissolve gold slower than cyanide. In the QCM tests the chloride-hypochlorite alternative showed highest dissolution rate of 8.6 mgcm-2h-1 at the redox potential of 900 mV vs. SHE. The thiocyanate system with ferric ion dissolved gold at a rate of 3.4 mgcm-2h-1 at the redox potential of 620 mV vs. SHE. Thiourea system with ferric ion showed the dissolution rate of 1.65 mg cm-2 h-1 at the redox potential of 450 mV vs. SHE. The results of the rapid tests were comparable with literature and were included in the case base of the Auric Advisor decision-support tool.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 1; 269-279
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Impact assessment of effectiveness of thiourea and THAM for corrosion process on carbon steel in calcium chloride environment
    Autorzy:
    Malinowski, S.
    Jaroszyńska-Wolińska, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/390655.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
    Tematy:
    corrosion inhibitor
    thiourea
    THAM
    carbon steel
    anticorrosive properties
    Opis:
    The main objective of this paper is to present a comparison of the corrosion inhibiting effect of thiourea and THAM (tri(hydroxymethyl)aminomethane) on carbon steel samples immersed in calcium chloride solutions. The testing has shown that to inhibit the corrosive action of the calcium chloride solution, the thiourea solution can be successfully replaced by the THAM solution. The study was performed with the use of st3s, structural and reinforcing steel. In the case of st3s steel samples, the application of the 0.01% THAM solution causes a decrease of its weight loss by about 60%. The application of a 10-times stronger THAM solution causes an increase of the corrosion inhibition on the tested samples by about 20%. A combined protective action of the thiourea and THAM solutions brings about an increase of the corrosion process inhibition by about 70% both for the st3s and the structural samples. The 0.01% and 0.1% THAM solutions applied to inhibit the corrosion process on structural samples cause an increase of the corrosion protection by about 50% and 15% respectively.
    Źródło:
    Budownictwo i Architektura; 2016, 15, 2; 65-72
    1899-0665
    Pojawia się w:
    Budownictwo i Architektura
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prospects for thiourea as a leaching agent in Colombian gold small-scale mining: a comprehensive review
    Autorzy:
    Borda, Johana
    Torres, Robinson
    Powiązania:
    https://bibliotekanauki.pl/articles/2201416.pdf
    Data publikacji:
    2022
    Wydawca:
    Główny Instytut Górnictwa
    Tematy:
    górnictwo
    złoto
    cyjanek
    tiomocznik
    mining
    gold
    cyanide
    thiourea
    Opis:
    Thiourea, as an alternative medium, is one of the most promising leaching agents for gold recovery by its commercial benefits and research challenges associated with performance and environmental impacts. This review article describes the operational conditions for the use of Thiourea vs cyanide, its chemistry, limitations, toxicity factors, environment, and recovery processes. Although thiourea gold extraction processes have not been applied on a large scale due to the instability of the reagent, its potential to overcome the limitations of cyanide is attractive to the process; with pH, potential, oxidant dosage, and temperature control, solubilized gold thiourea species are achieved. These can be recovered from the pregnant leach solution through methods such as activated carbon absorption and adsorption, polyurethane foams, ion exchange, and electrodeposition.
    Źródło:
    Journal of Sustainable Mining; 2022, 21, 4; 298--308
    2300-1364
    2300-3960
    Pojawia się w:
    Journal of Sustainable Mining
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and characterization of thiourea
    Autorzy:
    Dai, Chuanbo
    Zhang, Hongyu
    Li, Ruiduan
    Zou, Haifeng
    Powiązania:
    https://bibliotekanauki.pl/articles/778378.pdf
    Data publikacji:
    2019
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    Urea
    Lawesson’s reagent
    thiourea
    vulcanization reaction
    Nucleophilic substitution
    Opis:
    Herein, a simple and effective method for the preparation of thiourea using a nucleophilic substitution reaction is reported. Urea and Lawesson’s reagent were used as the raw materials to prepare thiourea via a one-step method involving the sulfuration reaction, and the reaction mechanism was analyzed. The effect of the reaction time, reaction temperature, and mass ratio of the raw materials on the yield of thiourea were investigated.The most beneficial conditions used for the reaction were determined to be: Reaction time = 3.5 h, reaction temperature = 75°C, and mass ratio of urea to Lawesson’s reagent = 2:1. Under these optimal conditions, the average yield of thiourea over five replicate experiments was 62.37%. Characterization using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) showed that the as-synthesized substance was thiourea. Our synthetic method has the advantages of high yield, mild reaction conditions and simplicity.
    Źródło:
    Polish Journal of Chemical Technology; 2019, 21, 3; 35-39
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis, characterization of biologically potent novel chalcones bearing urea, thiourea and acetamide linkages
    Autorzy:
    Mewada, N. S.
    Shah, D. R.
    Chikhalia, K. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/412032.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Chalcone
    urea
    thiourea
    acetamide
    antimicrobial activity and antifungal activity
    Opis:
    Three series of some novel chalcone based urea, thiourea and acetamide derivatives were designed, synthesized and screened for their antimicrobial and antifungal activities. All the synthesized compounds are first reported. The structures of the compounds were elucidated with the aid of elemental analysis and spectral methods including IR, 1H-NMR spectral data. The prepared compounds were evaluated for antibacterial activity against two Gram-positive bacteria (Staphylococcus aureus, Staphylococcus pyogenus), two Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli). The title compounds were also investigated for their antifungal activity using the broth micro dilution method. The bioassay results showed that compounds a few compounds showed good to superior in vitro antibacterial and antifungal activity.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 17, 3; 281-294
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Catalytic Effect of Mn2O3 Nanoparticles on the Ignition Reaction of Pyrotechnic of Ammonium Nitrate(V)/Thiourea
    Autorzy:
    Pouretedal, H. R.
    Ravanbod, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/358302.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    ammonium nitrate(V)
    thiourea
    non-isothermal kinetic
    ignition reaction
    Mn2O3 nanoparticles
    Opis:
    The non-isothermal TG/DSC technique has been used to study the kinetic triplet and heat of ignition reaction of ammonium nitrate(V) (AN)/thiourea (TU) pyrotechnic in the presence of Mn2O3 catalyst nanoparticles under an argon atmosphere at different heating rates (5 K·min−1, 10 K·min−1, 15 K·min−1 and 20 K·min−1). The activation energies for the ignition reaction of AN/TU were calculated using the non-isothermal isoconversional Kissinger-Akahira-Sunose (KAS) and Friedman equations for different conversion fraction (α) values in the range 0.1-0.9. The pre-exponential factor and kinetic model were determined by means of the compensation effect and the selected model was confirmed by a nonlinear fitting method. The average activation energies in the absence and presence of 5 wt.% Mn2O3 nanoparticles were 110.1 kJ·mol−1 to 117.3 kJ·mol−1 for the reaction model A3 (g(α) = [−ln(1−α)]1/3), and 86.5 kJ·mol−1 to 101.8 kJ·mol−1 for the reaction model A4 (g(α) = [−ln(1−α)]1/4). The evolved heat (ΔH) of ignition reaction in the presence of Mn2O3 was about 4 times that in the absence of the nano-sized Mn2O3.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 2; 430-447
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of optical illumination and magnetic field on the electroconductive and polarization properties of clathrate GaSe>, synthesized under lighting
    Autorzy:
    Ivashchyshyn, Fedir
    Maksymych, Vitaliy
    Calus, Dariusz
    Matulka, Dariya
    Chabecki, Piotr
    Kunynets, Andrii
    Powiązania:
    https://bibliotekanauki.pl/articles/2173684.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    GaSe
    thiourea
    anthracene
    clathrate
    impedance spectroscopy
    quantum capacitance
    memristive effect
    tiomocznik
    antracen
    klatrat
    spektroskopia impedancyjna
    pojemność kwantowa
    efekt memrystyczny
    Opis:
    GaSe> clathrate with a hierarchical subhost> type architecture was formed under illumination and its electrically conductive properties were studied. The method of impedance spectroscopy studied the frequency behavior of the real and imaginary parts of the complex total impedance in the range of 10 -3-10 6 Hz. The measurements were performed under normal conditions, in a permanent magnetic field (220 kA/m), or under light illumination (for a standard solar spectrum AM 1.5 G total available power is 982 W/m 2). The structure of the impurity energy spectrum at the Fermi level was investigated by the method of thermostimulated discharge in the temperature range from 240 to 340 K. Using Jebol-Pollack theoretical approaches based on impedance spectra, the parameters of the impurity energy spectrum were calculated, such as the density of states at the Fermi level, the jump radius , the scatter of trap levels near the Fermi level and the real density of deep traps. As evidenced by studies, illumination during clathrate synthesis, forms an internal electret polarization, which leads to abnormal behavior of the photoresistive effect and to the appearance of the memristive effect. The imposition of a permanent magnetic field during the measurement of complex resistance leads to the appearance of quantum capacitance.
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 5; art. no. e143104
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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