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    Wyświetlanie 1-3 z 3
    Tytuł:
    Adsorption behavior of calcium ions and its effect on cassiterite flotation
    Autorzy:
    Chen, Yumeng
    Feng, Dongxia
    Tong, Xiong
    Powiązania:
    https://bibliotekanauki.pl/articles/110731.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    cassiterite
    calcium ions
    adsorption
    flotation
    salicylhydroxamic acid
    Opis:
    Naturally, most of the cassiterite co-exists with sparingly soluble calcite, which makes it difficult to be fully utilized. Due to the adsorption of calcium ions dissolved from calcite, surface properties of cassiterite and its floatability can be influenced. Adsorption tests show calcium ions can adsorb on cassiterite surface. In the presence of Ca2+, the zeta potentials of cassiterite shift to more positive values and the isoelectric point of cassiterite increases from pH 4.4 to pH 4.9. XPS results show that after calcium ions treatment, a strong calcium spectral peak at 347.65 eV is detected on the cassiterite surface and the chemical circumstance of oxygen atoms is changed. The presence of Ca2+ can significantly depressed the flotation behavior of cassiterite with salicylhydroxamic acid (SHA) as collector. Its recovery is decreased by 26.03% compared to that without Ca2+ at SHA dosage of 8.0×10-4 mol/dm3. When increasing SHA concentration to 9.0×10-4 mol/dm3 and above, the depression effect is partly compensated and the recovery rises by about 20%. Contact angle values of cassiterite measured by the bubble method correspond well to the flotation performance. Hence the depression mechanism of Ca2+ in cassiterite flotation can be interpreted in two aspects: 1) the consumption of SHA due to complexation reactions in pulp; 2) a decrease of effective adsorption site for SHA on cassiterite because of the adsorption of Ca2+.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 258-267
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation on different behavior and mechanism of Ca(II) and Fe(III) adsorption on spodumene surface
    Autorzy:
    Yu, F.
    Wang, Y.
    Wang, J.
    Xie, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/110230.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    spodumene surface
    calcium ions
    iron ions
    adsorption mechanism
    DFT calculation
    Opis:
    Behavior and mechanism of Ca2+ and Fe3+ adsorption on spodumene surface were investigated by micro flotation tests, zeta potential measurements, and density functional theory (DFT) calculation methods. The micro flotation tests showed that Ca2+ and Fe3+ activated the flotation of spodumene remarkably. However, the effect of Fe3+ was more significant than that of Ca2+. Additionally, Fe3+ significantly changed the zeta potential of spodumene while Ca2+ showed a little change. Meanwhile, the calculated adsorption energy of Fe3+ on spodumene surface was much greater than that of Ca2+ indicating that Fe3+ is more apt to be adsorbed on spodumene surface than Ca2+. The value of bond population in Ca-O illustrated that the bond of Ca-O consists of partial covalent proportion and some ionic component. On the contrary, the bond of Fe-O showed a relatively strong covalent property. The partial density of states (PDOS) of free Ca/Fe and the reacted O atom on spodumene (110) surface before and after the adsorption showed that Fe 3d orbital and O 2p orbital formed hybridization. The density of states (DOS) near the Fermi level of spodumene surface after adsorption with Fe3+ was much stronger than that with Ca2+.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2014, 50, 2; 535-550
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Improvement of plant heat tolerance by modification of xanthophyll cycle activity
    Autorzy:
    Trojak, Magdalena
    Skowron, Ernest
    Powiązania:
    https://bibliotekanauki.pl/articles/1178460.pdf
    Data publikacji:
    2017
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    ascorbic acid (AsA);
    calcium ions (Ca2+)
    dithiothreitol (DTT)
    heat stress
    plant protection products (PPPs)
    putrescine (Put)
    xanthophyll cycle
    Opis:
    Plants are sessile organisms hence environmental factors such as excessive light and high air temperature lead to significant reductions of their productivity and quality of gained yield. In fact, scientific and agriculture hubs make lots of efforts to improve crop tolerance to elevated temperature, selecting more tolerant varieties. We analyzed less expensive and highly efficient method to improve resistance of well-known cultivars of crop plant by reversible modification of xanthophyll cycle. It functions as a safety valve to adjust energy transfer and protects fragile structures of photosynthetic machinery from excessive light, especially accompanied by heat or water stress. Efficiency of modified xanthophyll cycle activity was measured after pre-treatment with four, chemically different regulators, with or without light illumination. Analyses were carried out on barley (Hordeum vulgare L.) cv. Zenek treated with ascorbic acid (AsA), dithiothreitol (DTT), putrescine (Put) and calcium ions (Ca2+). To measure the scale of thermal energy dissipation we traced energy transfer absorbed by PSII with PAM chlorophyll fluorescence technique. Results showed clear correlation between AsA (activator of violaxanthin de-epoxidase) treatment and stimulation of the Φ(NPQ) at increased temperature. DTT (inhibitor of violaxanthin de-epoxidase) decreased the cycle activity at 45 °C at the same time increasing its value at 35°C, caused by interaction with other enzymes. Action of Put (hydrogen ions buffer) concerned mainly a non regulated Φ(NO) energy quenching. We noticed that application of Ca(NO3)2 (Ca2+ source for enzyme activity) reduced the Φ(NPQ) at 45 °C and stimulated it at 25 °C. Obtained results confirmed postulated possibility of creating new type of plant protection products (PPPs) able to precisely manage natural mechanisms of heat resistance.
    Źródło:
    World Scientific News; 2017, 70, 2; 51-70
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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