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Wyszukujesz frazę "quenching constant" wg kryterium: Wszystkie pola

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    Wyświetlanie 1-3 z 3
    Tytuł:
    Electrical neutralization ability of polyaluminum chloride (PACl) coagulants with different OH–/Al3+ ratios by fluorescence quenching effect
    Autorzy:
    Chi, Fung Hwa
    Cheng, Wen Po
    Yu, Ruey Fang
    Chen, Zhao Feng
    Powiązania:
    https://bibliotekanauki.pl/articles/207968.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    stała Sterna-Volmera
    polichlorek glinu
    kwas humusowy
    fluorescencja
    Stern-Volmer constant
    polyaluminum chloride
    humic acid
    fluorescence
    Opis:
    The electrical neutralization ability of polyaluminum chlorides (PACls) with respect to humic acid was investigated by the fluorescence quenching method. The Stern–Volmer constant (Kq) at various pH and coagulation doses was determined for polyaluminum chlorides (PACl-B) of various basicities (B, B = [OH–]/[Al]). The experimental results show that under acidic conditions, the order of Kqvalues of PACl-B is PACl-2.5 > PACl-2.3 > PACl-1.5 > AlCl3. In solutions of pH = 7, the order of Kqvalues is PACl-1.5 > PACl-2.3 > PACl-2.5 > AlCl3. When pH > 7, aluminum ions are rapidly hydrolyzed, thus PACls of various basicities generally do not show capacity for electrical neutralization with humic acid. At pH = 6, all PACls-B obtain the maximum Kq values, indicating that humic acid and PACl-Bcoagulation process is less affected by H+ or OH– ions, and produces the best electrical neutralization ability. Compared to the past method of using surface potential as a means of determining the ability of neutralization of coagulation, the results of this study show that the Kq value of the quenching effect can reduce the experiment complexity.
    Źródło:
    Environment Protection Engineering; 2020, 46, 2; 25-39
    0324-8828
    Pojawia się w:
    Environment Protection Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical properties of (3-(acetamidomethyl)phenyl)boronic acid and its interactions with selected sugars
    Autorzy:
    Kur, K.
    Przybyt, M.
    Miller, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/410414.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Łódzka. Wydawnictwo Politechniki Łódzkiej
    Tematy:
    (3-(Acetamidomethyl)phenyl)boronic acid
    quenching constant
    pK
    lifetime
    3AAPBA
    stała wygaszania
    trwałość
    Opis:
    (3-(Acetamidomethyl)phenyl)boronic acid (3AAPBA)has at pH 7 absorbance maximum at 270 nm with molar absorbance coefficient 516 M-1cm-1. 3AAPBA exhibits weak fluorescence with maximum at 297 nm and quantum yield 0.062 ± 0.001. Fluorescence decay is monoexponential and the lifetime is 2.05 ± 0.01 ns. Interactions of 3AAPBA with selected sugars were studied by absorbance, steady-state and time-resolved fluorescence measurements. At pH 7 fluorescence of 3AAPBA is quenched only by fructose (with quenching constant 67.9 M-1) and to some extend by galactose. Addition of these two monosaccharides causes also changes of absorbance spectra of 3AAPBA. Acid-base dissociation of free 3AAPBA and its esters with sugars was studied by absorbance and steady-state fluorescence measurements in pH range from 4.5 to 11.00. Esterification of phenylboronic acid derivatives by sugars leads to increased acidity of them. In case of 3AAPBA the obtained values of pK indicate that affinity of studied sugars towards it can be ordered as follows: fructose > galactose > glucose > maltose > lactose > sucrose. At pHs higher than pK the fluorescence decays turn to biexponential with additional shorter component in lifetime which we propose to attribute to anionic form of 3AAPBA or its esters.
    Źródło:
    Biotechnology and Food Science; 2018, 82, 1; 15-27
    2084-0136
    2299-6818
    Pojawia się w:
    Biotechnology and Food Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Static quenching of ruthenium(II)-polypyridyl complexes by gallic acid and quercetin in aqueous and micellar media
    Autorzy:
    Sheeba, D
    Gnana Raj, G. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/412659.pdf
    Data publikacji:
    2014
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    Ru(II)-polypyridyl complex
    electron transfer
    quenching
    association constant
    Opis:
    The reactions of gallic acid and quercetin with the excited state Ru(II) complexes proceed through photoinduced electron transfer reaction in sodium dodecyl sulfate (SDS) and aqueous media at pH 11 and has been studied by luminescence quenching technique. The static nature of quenching is confirmed from the ground state absorption studies in both the media. The observed quenching rate constant (kq) values are sensitive to the nature of the ligand, medium and the structure of the quenchers. The electrostatic interaction of the cationic complexes with the anionic micelle reduces the kq values in SDS compared to that in aqueous medium.
    Źródło:
    International Letters of Chemistry, Physics and Astronomy; 2014, 13, 1; 21-31
    2299-3843
    Pojawia się w:
    International Letters of Chemistry, Physics and Astronomy
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-3 z 3

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