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    Wyświetlanie 1-6 z 6
    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:
    Sorbent-Catalyst for Acceleration of The Iron Oxidation Process
    Autorzy:
    Gomelya, Mykola
    Tverdokhlib, Mariia
    Shabliy, Tetyana
    Radovenchyk, Vyacheslav
    Linyucheva, Olga
    Powiązania:
    https://bibliotekanauki.pl/articles/1839169.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Inżynierii Ekologicznej
    Tematy:
    iron ions
    magnetite
    sorbent
    catalyst
    deironing
    sorption capacity
    Opis:
    In this work, the process of water deironing by using magnetite as a catalyst to accelerate the oxidation of iron ions in an aqueous medium was investigated. It was shown that the efficiency of iron ion extraction depends on the solution concentration, sorbent dose and contact time. In all cases, the use of magnetite accelerated the process of extraction of iron by more than an order of magnitude in comparison with similar experiments on the oxidation of iron without the addition of a catalyst. At the pH values greater than 6, the use of magnetite as a catalyst contributes to the deep purification of water from iron ions.
    Źródło:
    Journal of Ecological Engineering; 2021, 22, 3; 221-230
    2299-8993
    Pojawia się w:
    Journal of Ecological Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Generation of ·OH initiated by interaction of Fe2+ and Cu+ with dioxygen; comparison with the Fenton chemistry.
    Autorzy:
    Urbański, Norbert
    Beręsewicz, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/1044216.pdf
    Data publikacji:
    2000
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    superoxide dismutase
    autoxidation
    catalase
    free radical
    Fenton reaction
    hydroxyl radical
    iron ions
    copper ions
    desferrioxamine
    Opis:
    Iron and copper toxicity has been presumed to involve the formation of hydroxyl radical (·OH) from H2O2 in the Fenton reaction. The aim of this study was to verify that Fe2+-O2 and Cu+-O2 chemistry is capable of generating ·OH in the quasi physiological environment of Krebs-Henseleit buffer (KH), and to compare the ability of the Fe2+-O2 system and of the Fenton system (Fe2+ + H2O2) to produce ·OH. The addition of Fe2+ and Cu+ (0-20 μM) to KH resulted in a concentration-dependent increase in ·OH formation, as measured by the salicylate method. While Fe3+ and Cu2+ (0-20 μM) did not result in ·OH formation, these ions mediated significant ·OH production in the presence of a number of reducing agents. The ·OH yield from the reaction mediated by Fe2+ was increased by exogenous Fe3+ and Cu2+ and was prevented by the deoxygenation of the buffer and reduced by superoxide dismutase, catalase, and desferrioxamine. Addition of 1 μM, 5 μM or 10 μM Fe2+ to a range of H2O2 concentrations (the Fenton system) resulted in a H2O2-concentration-dependent rise in ·OH formation. For each Fe2+ concentration tested, the ·OH yield doubled when the ratio [H2O2]:[Fe2+] was raised from zero to one. In conclusion: (i) Fe2+-O2 and Cu+-O2 chemistry is capable of promoting ·OH generation in the environment of oxygenated KH, in the absence of pre-existing superoxide and/or H2O2, and possibly through a mechanism initiated by the metal autoxidation; (ii) The process is enhanced by contaminating Fe3+ and Cu2+; (iii) In the presence of reducing agents also Fe3+ and Cu2+ promote the ·OH formation; (iv) Depending on the actual [H2O2]:[Fe2+] ratio, the efficiency of the Fe2+-O2 chemistry to generate ·OH is greater than or, at best, equal to that of the Fe2+-driven Fenton reaction.
    Źródło:
    Acta Biochimica Polonica; 2000, 47, 4; 951-962
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wytrącanie i krystalizacja struwitu w obecności jonów żelaza(III)
    Continuous reaction crystallization of struvite in presence of iron(III) ions
    Autorzy:
    Hutnik, N.
    Matynia, A.
    Wierzbowska, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1287307.pdf
    Data publikacji:
    2010
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
    Tematy:
    struwit
    krystalizacja
    reakcja chemiczna
    strącanie
    jony żelaza(III)
    krystalizator o działaniu ciągłym
    krystalizator DT MSMPR
    struvite
    reaction crystallization
    iron(III) ions
    DT MSMPR crystallizer
    Opis:
    Przedstawiono wyniki badań dotyczących ciągłego wydzielania struwitu za pomocą jonów magnezu i amonu w warunkach stechiometrycznych z roztworów wodnych zawierających 1,0% mas. jonów fosforanowych(V) i jony żelaza(III). w zależności od stężenia tych jonów (1 ÷ 10 mg Fe3+ / kg roztworu), pH (9 ÷ 11) i średniego czasu przebywania zawiesiny w krystalizatorze (900 ÷ 3600 s) otrzymano produkty o średnim rozmiarze kryształów od 20 do 43 žm. wykazano, że jony żelaza(III) niekorzystnie oddziaływują na rozmiary kryształów struwitu (L m ok. 36 › 26 žm) i jednorodność ich populacji (CV = 71 › 97%). wytrącone z kryształami struwitu cząstki wodorotlenku żelaza(III), o rozmiarach często poniżej 1 žm, tworzyły aglomeraty, również na powierzchni kryształów struwitu. Obecność jonów żelaza(III) przyczyniła się do krystalizacji struwitu w postaci kryształów rurowych.
    The experimental results concerning continuous reaction crystallization of struvite from water solutions containing 1.0 mass % of phosphate(V) and iron(III) ions with magnesium and ammonium ions in stoichiometric conditions are presented. Depending on foreign ion concentration (1 ÷ 10 mg Fe3+ /kg of solution), pH (9 ÷ 11) and mean residence time of suspension in crystallizer (900 ÷ 3600 s) the crystal products of mean crystal size from 20 to 43 žm were obtained. It was proved that iron(III) ions affect struvite crystal sizes (L m ca. 36 › 26 žm) and their population homogeneity (CV = 71 › 97%) disadvantageously. The iron(III) hydroxide particles co-precipitated with struvite crystals, usually of size below 1 žm, formed agglomerates - also on the parent struvite crystal surfaces. Presence of iron(III) ions contributes struvite crystallization in characteristic tubular-shape form.
    Źródło:
    Chemik; 2010, 64, 12; 816-823
    0009-2886
    Pojawia się w:
    Chemik
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anticancer Activities of Ferrous and Ferric Ions in Progression, Proliferation, Angiogenesis, Invasion and Metastasis against Cancer and Tumor Cells
    Autorzy:
    Ishida, Tsuneo
    Powiązania:
    https://bibliotekanauki.pl/articles/1112780.pdf
    Data publikacji:
    2018
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Angiogenesis
    Cancer and tumor cell death
    Ferritin
    Ferroptosis
    Ferrous and ferric ions
    Invasion and metastasis
    Iron deficiency and overload
    ROS
    Opis:
    The process of ferroptotic death is characterized by the overwhelming, iron-depending accumulation of lethal lipid ROS. Unlike other forms of apoptotic and non-apoptotic death, this requirement for ROS accumulation appears to be universal. Redox cycling is a characteristic of transition metals such as iron (Ferritin Fe3+ ⇄ Ferrous Fe2+). Iron via the Fenton reaction can exacerbate the consequences of hydrogen peroxide (H2O2) production, leading to the generation of hydroxyl radicals. The superoxide ion can participate in regenerating ferrous iron that is required for the Fenton reaction. An excess of iron is toxic due to its ability to engage in redox cycling and promote free radical formation. Super oxide anion generation; O2 → ･O2－. Hydrogen peroxide production; ･O2－ + 2H+ + e- → H2O2. Haber-Weiss reaction; H2O2 + O2－ → ･OH + OH－ + O2. Fenton reaction; Fe2+ + H2O2 → Fe3+ + OH－ + ･OH. Reduction to Fe(Ⅱ); Fe3+ ＋ ･O2－ → Fe2+ + O2. Ferritin is stable in iron-rich conditions, whereas it is rapidly degraded under conditions of iron starvation and ferritin degradation can be led. New blood vessel formation in angiogenesis is fundamental to tumor growth, invasion, and metastatic dissemination. Iron deficiency will lead to the dysfunction of immune system, metabolic disorders, myasthenia and anemia, whereas, excess iron also damages several vital organs. Thus, iron is essential for multiple cell functions, but is also potentially deleterious reasons of its ability to generate free oxygen radicals, iron balance by continuously recycling and reusing cellular iron, storage in ferritin, and export through ferroportin protecting cells from free iron toxicity. However. the exact molecular mechanism involved on iron imbalance in development for tumor cells and the iron overload-mediated induction of apoptosis are required to be explored in future.
    Źródło:
    World News of Natural Sciences; 2018, 17; 111-129
    2543-5426
    Pojawia się w:
    World News of Natural Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Białka uczestniczące w transporcie jonów żelaza(II) w bakteriach gram-ujemnych
    Proteins involved in the ferrous ions transport in gram-negative bacteria
    Autorzy:
    Kierpiec, Karolina
    Stokowa-Sołtys, Kamila
    Powiązania:
    https://bibliotekanauki.pl/articles/1413209.pdf
    Data publikacji:
    2021
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    transport jonów żelaza(II)
    bakterie gram-ujemne
    Feo
    ferrous iron transport
    Hmu
    hemin uptake protein
    ferrous ions transport
    gram-negative bacteria
    Opis:
    Continuous increase in the number of multidrug-resistant strains forces us to look for drugs with completely new mode of action. One of the bacterial property determining the pathogenicity of these microorganisms is their ability to obtain iron. Because in the living environment of these single-celled individuals, its concentration is much lower than this necessary for their growth. For this reason, bacteria created various type of iron aquisition systems, including the Feo system, which mechanism of Fe2+ ion uptake is not fully understood, and protein from the Hmu family belonging to ABC transporters. The Feo transport system is one of the most common systems that is exclusively responsible for importing Fe2+ ions. It consists of three proteins: FeoA, FeoB and FeoC. FeoB is a transmembrane protein that is believed to play a key role in the mechanism of Fe2+ ion uptake. The other two components are cytoplasmic proteins. Both, FeoA and FeoC, are cytoplasmic proteins resembling the construction of transcription regulators. ABC transporters play an equally important role in maintaining iron homeostasis. These include proteins from Hmu family. HmuUV complex catalyses the import of these ions in hem iron form. The structure of this complex consists of TMD dimer (HmuU) and NBD dimer (HmuV). The HmuU is considered to be a permease - just like the FeoB described earlier while HmuV is the ATP binding protein.
    Źródło:
    Wiadomości Chemiczne; 2021, 75, 3-4; 375-394
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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