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    Wyświetlanie 1-6 z 6
    Tytuł:
    Dodecyl amine adsorption at different interfaces during bubble attachment/detachment at a silica surface
    Autorzy:
    Wang, X.
    Miller, J. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/110684.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    VSFS
    air bubble attachment
    amine adsorption density
    Opis:
    The reverse flotation of quartz and other gangue silicate minerals with alkyl amines is an important and well known strategy for the processing of iron ore, low grade bauxite ore, and phosphate rock. Some details of amine adsorption by quartz have been described in the literature, but little is known about the disposition of amine during bubble attachment. Now, a new experimental procedure involving vibrational sum frequency spectroscopy (VSFS) has been developed to provide, for the first time, a more detailed analysis of the state of dodecyl amine (DDA) adsorption at different interfaces during bubble attachment/detachment at a silica surface. The results show that the hydrophobic surface state at the silica surface is created by the transfer of a well-organized monolayer of DDA from the bubble surface to the silica surface during bubble contact and attachment.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 1; 81-88
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces
    Autorzy:
    Jin, J.
    Dang, L. X.
    Miller, J. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/109533.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    molecular dynamics simulations (MDS)
    film stability
    bubble attachment
    interfacial water structure
    Opis:
    Bubble attachment phenomena are examined using Molecular Dynamics Simulations (MDS) for the first time. The simulation involves a nitrogen nano bubble containing 906 nitrogen molecules in a water phase with 74,000 water molecules at molybdenite surfaces. During a simulation period of 1 ns, film rupture and displacement occurs. The attached nanobubble at the hydrophobic molybdenite face surface results in a contact angle of about 90º. This spontaneous attachment is due to a “water exclusion zone” at the molybdenite face surface and can be explained by a van der Waals (vdW) attractive force, as discussed in the literature. In contrast, the film is stable at the hydrophilic quartz (001) surface and the bubble does not attach. Contact angles determined from MD simulations are reported, and these results agree well with experimental and MDS sessile drop results. In this way, film stability and bubble attachment are described with respect to interfacial water structure for surfaces of different polarity. Interfacial water molecules at the hydrophobic molybdenite face surface have relatively weak interactions with the surface when compared to the hydrophilic quartz (001) surface, as revealed by the presence of a 3 Å “water exclusion zone” at the molybdenite/water interface. The molybdenite armchair-edge and zigzag-edge surfaces show a comparably slow process for film rupture and displacement when compared to the molybdenite face surface, which is consistent with their relatively weak hydrophobic character.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 1; 89-101
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of dissolved air on bubble attachment to highly oriented pyrolytic graphite
    Autorzy:
    Krasowska, M.
    Sellapperumage, P. M. F.
    Ralston, J.
    Beattie, D. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/110554.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    bubble attachment
    hydrophobic surface
    van der Waals interaction
    nanobubbles
    dissolved air
    Opis:
    The effect of air, dissolved in 0.1 M KCl solution, on bubble attachment to the smooth hydrophobic surface of highly oriented pyrolytic graphite was studied. The stability of a wetting film in such a system is governed by surface forces, i.e. electrostatic and van der Waals interactions. At the high ionic strength investigated, the electric double layer forces are both weak and of short range, therefore the stability of the wetting film is dominated by van der Waals interactions. The Hamaker coefficient for the highly oriented pyrolytic graphite-KCl aqueous solution-air system is negative and hence van der Waals interactions are repulsive. A repulsive force should stabilize the wetting film, preventing its rupture and bubble attachment to the highly oriented pyrolytic graphite surface. Many experimental studies have found that wetting films are not stable at graphite or coal surfaces, and air bubbles attach. In the present experiments, the stability of the wetting films decreased with increasing amount of dissolved air. The time required for film drainage, rupture, and air bubble attachment was shortened by two orders of magnitude when the experiments were performed in air saturated 0.1 M KCl solution. This instability was attributed to an increasing number of nano- and submicron- bubbles nucleated at the graphite surface. The Hamaker coefficient across the air-KCl aqueous solution-air system is positive and hence van der Waals interactions are attractive, resulting in wetting film rupture and macroscopic air bubble attachment to a highly oriented pyrolytic graphite surface decorated with resident nano- and submicro-metre bubbles.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 1; 163-173
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Surface chemistry and flotation properties of galena and pyrite particles in the presence of xanthate- monothiophosphate- thiocarbamate collectors
    Autorzy:
    Ercelik, Gokhan
    Terzi, Mert
    Kursun, Ilgin
    Ozdemir, Orhan
    Powiązania:
    https://bibliotekanauki.pl/articles/24148622.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    pyrite
    galena
    zeta potential
    bubble-particle attachment time
    micro-flotation
    Opis:
    In this study, surface chemistry and flotation properties of the gold-bearing galena and pyrite minerals of Menderes region, Izmir, Turkey were investigated with the use of xanthate-thiocarbamate-monothiophosphate collectors. In this context, the micro-flotation experiments, the zeta potential, and bubble-particle attachment time measurements were conducted in the presence of Thiophosphate (Aero S-8045), Xanthate (SIBX), and Thiocarbamate (Aero float MX-505) collectors. In the case of micro-flotation experiments, the MX-505 exhibited higher flotation efficiency for both minerals compared to SIBX and S-8045 collectors. In the micro-flotation tests conducted on galena and pyrite, while the flotation recovery of 99.82% and 81.96% were obtained with MX-505, the flotation recovery of 89.64% and 62.50% were reached in the case of using SIBX. Furthermore, the S-8045 resulted in the flotation recovery s of 75.09% and 25.45% for galena and pyrite, respectively. In the case of zeta potential experiments as a function of pH, the galena mineral showed a negative charge between -17.22 to -41.42 mV at pH 5 – 11, no point of zero charge (pzc) was determined, and the pzc of pyrite was determined as pH≈8. The bubble-particle attachment time experiments performed in the presence of S-8045, SIBX, and MX-505 collectors indicated that the attachment efficiency was 100% in the presence of MX-505 at 12.5-75 g/Mg dosages and 1-1000 ms contact times. These results revealed that there was an extraordinarily strong interaction between the galena/pyrite and the air bubbles in the presence of MX-505. The results obtained within this study indicated that galena and pyrite minerals showed inherently less than 25% natural floatability which can only be enhanced under specific conditions. The results obtained within this study indicated that galena and pyrite minerals showed inherently low natural floatability which can only be enhanced under specific conditions. In the tests conducted on these minerals, galena mineral showed higher than %20 natural floatability compared to pyrite mineral, and collectors produced from thiocarbamates have shown greater effectiveness compared to xanthate and thiophosphate.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2023, 59, 5; art. no. 167947
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Three-phase contact line expansion during air bubble attachment to hydrophobic solid surface – experiment and modeling
    Autorzy:
    Basarova, P.
    Soušková, K.
    Zawala, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/110269.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    Attachment
    simulations
    bubble
    three-phase contact
    dewetting
    Opis:
    Kinetics of spreading of the three-phase contact hole (dewetting) formed by an air bubble colliding with hydrophobic solid surface, after rupture of intervening liquid film, was studied both experimentally and numerically. During experiments it was found that evolution of the TPC line diameter with time occurs with characteristic S-shaped trend which, in consequence, causing rather unexpected maxima at the TPC line spreading velocity curves. It was determined that position of this maximum appears after 1-2 ms after TPC hole formation and its position (in respect to time) depends on the bubble diameter. In solution of surface-active substance this maximum was much smoother and longer. By means of complementary numerical calculations the source of maxima existence and differences in their position and shapes were explained. It was concluded that this effect has only hydrodynamic origin, caused by different course of bubble shape pulsations during TPC line formation and spreading, which depends on degree of liquid/gas interface immobilization (fluidity retardation).
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1095-1106
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A study of bubble-particle interactions in a column flotation process
    Autorzy:
    Cheng, G.
    Shi, C.
    Yan, X.
    Zhang, Z.
    Xu, H.
    Lu, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/109635.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    particle
    bubble
    column flotation
    collision
    attachment
    detachment
    Opis:
    Bubble-particle interactions play an important role in flotation. This study examines the behaviour of bubble clusters in a turbulent flotation cell. Particularly, the bubble-particle interaction characteristics in flotation are investigated. The bubble size in a flotation column was measured using an Olympus i-SPEED 3 high-speed camera. Relationships between the circulating volume, bubble size and bubble terminal velocity were discussed. Probabilities of collision, attachment, detachment and acquisition between bubbles and particles in different circulating volumes were calculated based on the flotation kinetic theory. Using the extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) theory, the relationship between the potential energy and distance in bubble-particle interaction was analysed. The results demonstrated that as the circulating volume increased, the bubble size and velocity decreased. When the circulating volume increased from 0.253 to 0.495 m3/h, the bubble diameter decreased from 511 to 462 μm, and the corresponding bubble velocity decreased from 43.1 to 37.5 mm/s. When the circulating volume remained constant as the particle size increased, probabilities of collision, attachment, detachment and acquisition increased. When the particle size remained constant as the circulating volume increased, these probabilities also increased. At a constant circulating volume as the particle size increased, the absolute value of the total potential energy between the particle and bubble increased. When the distance between the bubble and particle was 30 nm, the energy barrier appeared.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 1; 17-33
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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