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    Wyświetlanie 1-9 z 9
    Tytuł:
    Quantifying the spreading factor to compare the wetting properties of minerals at molecular level – case study: sphalerite surface
    Autorzy:
    Mohseni, M.
    Abdollahy, M.
    Poursalehi, R.
    Khalesi, M. R.
    Powiązania:
    https://bibliotekanauki.pl/articles/109377.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    wettability
    contact angle
    molecular simulation
    sphalerite
    spreading factor
    Opis:
    Spreading of water droplet on sphalerite surface was quantified at molecular level and was utilized for comparison of the wetting properties of sphalerite protonated and hydroxylated surfaces. Molecular dynamic simulations were used to characterize the wetting of sphalerite (110) plane. Experimental contact angles of water droplet on sphalerite surfaces were measured and the results were compared with simulated contact angles to ensure that the simulations are accurate enough for calculation of spreading factors. Shape descriptors such as perimeter, area, Feret’s diameters and circularity were used to characterize the shape of droplet-sphalerite interface at molecular level. Using the shape descriptors, different spreading factors were defined and calculated spreading factors were correlated with simulated contact angle. It was shown that spreading factors which were defined as the volume of water droplet divided by the area and Feret’s diameters, with correlation coefficient of 0.98 and 0.97, can be used as accurate tools for wetting comparison of functionalized sphalerite surface at molecular scale. Proposed approach also can be used for investigations on the effect of surface chemical and physical anisotropies on preferred wetting in specific direction at molecular scales.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 3; 646-656
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selective flotation of siderite and quartz from a carbonate-containing refractory iron ore using a novel amino-acid-based collector
    Autorzy:
    Gu, X.
    Zhu, Y.
    Li, Y.
    Han, Y.
    Powiązania:
    https://bibliotekanauki.pl/articles/110222.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    flotation
    quartz
    hematite
    siderite
    refractory iron ores
    molecular simulation
    Opis:
    A novel and highly-efficient amino-acid-based collector, α-ethylenediamine lauric acid (α-EDA-LA), was studied to selectively beneficiate carbonate-containing refractory hematite ores. Single mineral and synthetic mixture flotation tests were carried out to investigate its floating performance. Zeta potential, fourier transform infrared spectroscopy (FTIR) and Density Functional Theory-based molecular simulation were used to identify the adsorption mechanism. The flotation results showed that quartz could be collected effectively at pH 11.0-12.0 in the reverse flotation. For siderite, the recovery peaked at 83.4% at pH 8.0, where siderite presented different floatability from magnetite and hematite. Exploiting such difference, the separation of siderite could be achieved. Zeta-potential measurements showed that α-EDA-LA adsorption on the surfaces of siderite and quartz decreased the corresponding zeta potentials at pH of 8.0-10.0 and 8.0-12.0, respectively. This means the adsorption overcome the electrostatic repulsion between α-EDA-LA and the mineral surfaces. The molecular simulation indicated that no chemisorption took place between α-EDA-LA and quartz. FTIR analysis suggested that α-EDA-LA was adsorbed on quartz via hydrogen bonding. The adsorption of α-EDA-LA on siderite surface was dominated by chemisorption, while further enhanced by hydrogen bonding. This study filled the gap in the research on siderite flotation reagents and its adsorption mechanism.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 3; 803-813
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular simulation study on hydration of low-rank coal particles and formation of hydration film
    Autorzy:
    Xia, Yangchao
    Yang, Zili
    Xing, Yaowen
    Gui, Xiahui
    Powiązania:
    https://bibliotekanauki.pl/articles/949689.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    low rank coal
    water molecule
    hydration film
    molecular simulation
    Opis:
    Water molecules in low-rank coal (LRC) significantly influence its upgrading and utilization. To investigate the hydration of LRC particles and the formation of a hydration film, molecular simulation techniques were innovatively used, including molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The adsorption of water molecules on LRC and various oxygen-containing groups was analyzed. The results show that water molecules adsorb close to the LRC surface and form a large overlapping layer at the LRC/water interface. The radial distribution functions (RDFs) show that the adsorption affinity of water molecules on oxygen-containing sites is stronger than that on carbon-containing sites, and the RDF peaks indicate the existence of a hydration film. Moreover, the differences in adsorption between various oxygen-containing groups depend on both the number of hydrogen bonds and the adsorption distances. The calculated binding energies indicate that the adsorption capacity follows the order carboxyl > phenolic hydroxyl > alcoholic hydroxyl > ether linkage > carbonyl. Experimental results show that a high sorption rate exists between water vapor and LRC samples at the beginning of sorption, which verified the simulation results.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 2; 586-596
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Water film structure during rupture as revealed by MDS image analysis
    Autorzy:
    Truong, N. T.
    Dang, L. X.
    Lin, C.-L.
    Wang, X.
    Miller, J. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/110251.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    image processing
    molecular dynamics simulation
    film stability
    molecular porosity
    Opis:
    The structure of thin water films during the rupture process was investigated by a new approach, which combines molecular dynamics simulation (MDS) with image processing analysis. The analysis procedure was developed to convert MDS trajectories to readable 3D images. The water films were studied at different thicknesses by MDS to determine the critical thickness at which the film ruptures. The potential energy of each specific film thickness during the simulation time was analyzed, and the results showed that the potential energy of stable films remained unchanged while the potential energy kept decreasing for films which ruptured during the simulation time. By applying the new procedure, the molecular porosity, which is defined as the void fraction between the volume of molecular pores in the water film and the total volume of the water film, was calculated. The results of molecular porosity for different film thicknesses during the simulation time suggested a critical molecular porosity as 49%. In other words, stable films have a molecular porosity of less than 49%. If a water film has a molecular porosity greater than 49%, rupture occurs during the simulation.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1060-1069
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Application of sodium dodecyl glycinate to the flotation of deslimed molybdenum tailings
    Autorzy:
    Bai, Yang
    Li, Caixia
    Song, Wangfang
    An, Hongyun
    Zhao, Jingyu
    Powiązania:
    https://bibliotekanauki.pl/articles/109790.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sodium dodecyl glycinate
    molybdenum tailings
    molecular simulation
    nonmetallic minerals
    amino acid collector
    Opis:
    By researching the nonmetallic minerals in molybdenum tailings, this paper investigated the possible application of sodium dodecyl glycinate (SD) to deslimed tailings as an alternative to the large dosage and complex flotation reagent systems of conventional combination collectors (dodecylamine and sodium oleate). The floatability differences of nonmetallic minerals under different SD dosages were analyzed via pure mineral flotation experiments, and the adsorption behavior of SD onto different mineral surfaces was analyzed by quantum chemical calculations. The results of the calculated adsorption structures and energies of the different mineral surfaces show that SD was chemically adsorbed onto the albite (001), phlogopite (010), diopside (110), dolomite (101), calcite (104) and calcite (101) surfaces and that physical adsorption occurred at the phlogopite (001) surface. The corresponding adsorption trend was dolomite > calcite > diopside > albite > phlogopite. These results theoretically verify the feasibility of applying SD to the flotation of nonmetallic minerals in tailings and provide a basis for the selection of inhibitors needed for separating phlogopite from other minerals. In the flotation of deslimed molybdenum tailings, the recoveries of the nonmetallic minerals achieved with SD were close to those in pure mineral flotation, which was greater than the recoveries achieved with dodecylamine and sodium oleate (NaOl), and the dosage was reduced by approximately 25%.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 5; 1120-1131
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flotation and molecular dynamics simulation of muscovite with mixed anionic/cationic collectors
    Autorzy:
    Bai, Yang
    Li, Caixia
    An, Hongyun
    Wang, Guoliang
    Zhao, Xin
    Zhang, Jinqi
    Powiązania:
    https://bibliotekanauki.pl/articles/110125.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    muscovite
    mixed anionic/cationic collectors
    flotation
    molecular dynamics simulation
    Opis:
    In this study, three kinds of anionic collectors (sodium oleate (NaOl), sodium dodecyl sulfonate (SDS) and naphthenic acid (NA)) were used in combination with dodecylamine (DDA) to investigate the flotation behavior of muscovite under the action of different mixed anionic/cationic collectors, and their mechanisms for adsorption on the muscovite (001) Surface were clarified using molecular dynamics simulations. The flotation results indicated that different mixed anionic/cationic collectors could improve the recovery of muscovite to varying degrees, but the optimum molar ratio of anionic collectors to DDA and the optimum mixed collector dosage were different. Molecular dynamics simulations showed that the mixed anionic/cationic collectors could significantly increase the hydrophobicity of the muscovite, as evidenced by the decrease in the calculated water molecule density on the muscovite surface and the diffusion coefficient of water molecules at the solid/liquid interface. The interaction between the amino group and the polar group of anionic collectors reduced the electrostatic repulsion between DDA cations and theoretically increased the adsorption capacity of the mixed anionic/cationic collectors on the muscovite surface. Moreover, DDA/NA and DDA/NaOl could improve the calculated carbon atom density on the muscovite surface, which enhanced the hydrophobic association between nonpolar carbon chains, thus further achieving an enhanced flotation performance.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 2; 313-324
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of oxidation on the wetting of coal surfaces by water: experimental and molecular dynamics simulation studies
    Autorzy:
    Li, E.
    Lu, Y.
    Cheng, F.
    Wang, X.
    Miller, J. D.
    Powiązania:
    https://bibliotekanauki.pl/articles/109792.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    wettability
    oxidation
    molecular dynamics simulation
    hydrogen bonding
    contact angles
    coal surfaces
    Opis:
    The wettability of coal surfaces by water continues to be one of the key factors which determines the success of coal flotation. Consequently, oxidation of coal surfaces is a fundamental issue of interest. In this work, the effect of oxidation on the wetting of coal surfaces and the interaction between water molecules and oxygen-containing sites at the coal surface was investigated based on advancing/receding contact angle measurements and molecular dynamics simulations. For the simulation studies, a flat coal surface was constructed with the assistance of the molecular repulsion between graphite surfaces and the assembly of Wiser coal molecules. Our results indicated that the simulated advancing and receding contact angles were very similar, and both of them decreased, as expected, with an increase of hydroxyl sites at the coal surface. The good agreement between the simulated advancing/receding contact angles and the experimental receding contact angle values suggested that the configuration of the systems and the set of parameters for the simulation were appropriate. The spreading of water is mainly due to the hydrogen bonds formed between the interfacial water molecules and the hydroxyl sites at the coal surface. The hydroxyl groups show stronger hydration capacity than other oxygen-containing groups according to the calculated hydrogen bonds and interaction energies.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2018, 54, 4; 1039-1051
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of the oxygen-containing functional group on the adsorption of hydrocarbon oily collectors on coal surfaces
    Autorzy:
    Wan, He
    Hu, Xianglin
    Luukkanen, Saija
    Qu, Juanping
    Zhang, Chonghui
    Xue, Jiwei
    Li, Hui
    Yang, Wei
    Yang, Shenghong
    Bu, Xianzhong
    Powiązania:
    https://bibliotekanauki.pl/articles/2146920.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    oxygen-containing functional groups
    hydrocarbon oily collectors
    molecular dynamics simulation
    coal surfaces
    adsorption
    Opis:
    The oxygen-containing functional groups (OCFG) on the coal surface affect the adsorption effect of hydrocarbon oily collectors (HOC). An investigation of the interaction between the HOC and OCFG in the absence and presence of water is conducive to understanding the effect of OCFG type on the adsorption of HOC on the coal surface. In this paper, FTIR analysis was used to analyze the OCFG type of coal surface. The adsorption behavior of HOC on different OCFG surfaces was investigated using molecular dynamics simulation. The results indicated the presence of OCFG such as -OH, -COOH, -C=O, and -COCH3 on the coal surface. In conditions without water, the effect of OCFG on HOC adsorption capability follows the order -COOH > -C=O > -OH > -COCH3. In an aqueous solution, the effect of OCFG on HOC adsorption capability follows the order -C=O>-COCH3>-OH>-COOH. Moreover, the hydrophilicity of OCFG is the key factor that affects the adsorption effect of HOC. In other words, the adsorption effect of HOC on the coal surface in an aqueous solution does not depend on the strength of the interaction between the OCFG and HOC in the absence of water, but on the hydrophilicity of the OCFG. The -COOH and -OH on the coal surface are not conducive to the adsorption of HOC onto the coal surface. Masking the -COOH and -OH of the coal surface is beneficial in improving the coal flotation performance with HOC as a collector.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 4; art. no. 149937
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Morphological analysis of organo-montmorillonites via MD simulations
    Autorzy:
    Karataş, Deniz
    Tekin, Adem
    Can, Muhammed F.
    Xu, Zhenghe
    Çelik, Mehmet S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2146936.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    organo-montmorillonite
    tetradecyl dimethyl ethyl benzyl ammonium chloride
    molecular dynamics simulation
    cation exchange capacity
    binding energy
    Opis:
    Adsorption on clay surfaces has been studied intensively in recent years. The most curious subject of these studies, which are generally experimental, is how the surfactants are adsorbed at the atomic level to the surface. In this study, the adsorption of quaternary amine salt (tetradecyl dimethyl ethyl benzyl ammonium chloride–TDEBAC) to sodium montmorillonite (Na-MMT) with various cation exchange capacities (CEC) was investigated by using Molecular Dynamics (MD) simulation. In the simulations, as in the experimental studies, it was revealed that the surfactants were both adsorbed on to basal surfaces and settled between the layers. From the morphological analysis obtained from MD simulations, it was calculated that the inter-molecular interaction between the layers was higher than on the basal surface. For example, for the model with 118 CEC motif, the binding energy of all three surfactants in the models with the hydrophilic heads facing the same direction was calculated as -678.18 kcal/mol at the basal surface, while this value was found to be -688.90 kcal/mol in the interlayer. The more striking result is that in the simulations made by turning the head of the middle one of the three surfactants towards the tails of the right and left ones, only -34.86 kcal/mol binding energy was calculated on the basal surface, while this value was -525.63 kcal/mol in the interlayer. As compared middle reversed surfactant models with the same direction ones, despite increased CEC the intermolecular interaction decreased for the basal surface, but the interaction increased between the layers.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152499
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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