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    Wyświetlanie 1-7 z 7
    Tytuł:
    Adsorption behavior of surfactants on lignite particles with different densities in aqueous medium
    Autorzy:
    Wang, J.
    He, Y.
    Wen, B.
    Ling, X.
    Xie, W.
    Wang, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/110538.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    interfacial surface free energy
    adsorption
    lignite
    surfactant
    Washburn equation
    Opis:
    Lignite is well known for its strong hydrophilicity and hard-to-float properties. However, the surface free energy of the solid is made up of two components, that is the Lifshitz-van der Waals and acid-base interaction energy. Differences in these two components between the low ash (lower density) and high ash fraction (higher density) provide a benefit for improving the separation efficiency through introducing surfactants in flotation. In this paper, thermodynamic characterization of three density lignite fractions was measured by a Washburn dynamic method. Combining the Washburn equation and Van Oss-Chaudhury-Good theory, the surface free energy components of three samples were calculated according to the wetting process by n-hexane, diiodomethane, deionized water and ethylene glycol. The Lifshitz-van der Waals part of surface free energy reduced with the coal density increase, especially between fractions of -1.45 g/cm3 and 1.45-1.80 g/cm3, while the Lewis base part increased slightly. The interfacial interaction free energies between the surfactant and lignite in aqueous medium indicated that the low hydrophilic index benefited for the stronger adsorption intensity. Increase of the surfactant Lifshitz-van der Waals component increases the adsorptive intensity on lower density lignite and the repulsive intensity on higher density lignite, which is beneficial for separation.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 996-1008
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Control of glass surface wettability via esterification with n-alkyl alcohols
    Autorzy:
    Kruszelnicki, Mateusz
    Polowczyk, Izabela
    Kowalczuk, Przemyslaw B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2146948.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    hydrophobicity
    surface free energy
    contact angle
    zeta potential
    roughness
    Opis:
    Surface wettability plays an essential role in many processes and materials applications. It depends mainly on the surface roughness and chemical composition, thus through a controlled modification of these parameters, the wettability can be restrained. Glass is an inorganic solid material, composed mainly of amorphous silica, which surface, due to the presence of reactive hydroxyl groups, can be quite easily chemically modified. This feature can be used to control the wettability of glass by reaction with organic compounds. In this study, the esterification of glass silanol groups with n-alkyl alcohols (Cn/H2n+1/OH, n=3, 4, 6, 8, 10) was employed to modify its wettability. The effect of such modification on the physicochemical properties of glass surface was comprehensively investigated and characterised by the water contact angle, surface free energy, zeta potential, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) measurements. We demonstrate that the wettability of the esterified glass surface is strongly dependent on both the chain length of used alcohol and modification time. The alcohol molecule binds to the glass surface through a Si-O-C bond, leading to the formation of a monolayer that does not significantly affect the surface morphology and zeta potential. Conducted studies provided a broader view of the influence of this technique for modifying surface wettability on its physicochemical properties.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 2; art. no. 145147
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of dry grinding on physicochemical and surface properties of talc
    Autorzy:
    Arsoy, Z.
    Ersoy, B.
    Evcin, A.
    Icduygu, M. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/109327.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    talc
    grinding
    contact angle
    surface free energy
    oil absorption
    whiteness
    Opis:
    In this study the effect of dry grinding on hydrophobicity, surface free energy (SFE), particle size distribution, surface area, porosity, oil absorption, and whiteness of talc was investigated. The dry grinding was performed in a vibrating ball mill at various grinding times (5-150 min) by keeping the grinding parameters constant such as the number of ball, ball size, the amount of talc, vibration frequency and amplitude. Then, the contact angle measurements were performed on disc-shaped samples produced under a hydraulic press by using a sessile drop method with different liquids (water, formamide, diiodomethane, and ethylene glycol), and surface free energies (mJ/m2) were calculated according to OCG-AB (van Oss-Chaudhury-Good Acid-Base) method by using the obtained contact angle values. In addition, the physicochemical analyses given above were carried out for each ground sample. According to the obtained results, the water contact angle and SFE of the original sample were 63.800 and 48.70 mJ/m2, respectively. The lowest and highest contact angle values for the samples were obtained as 59.300 and 70.770 at grinding times for 5 and 15 min, respectively. It was also determined that the grinding time over 30 min showed no significant effect on the contact angle and SFE values of the samples. Similarly, the grinding time vs. SFE, and the grinding time vs. contact angle curves showed a similar trend. Parallel to the increase in the surface area upon the grinding, a small increase in the oil absorption and whiteness of talc was also determined.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 1; 288-306
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Electrokinetic and surface properties of some methacrylate-based copolymers
    Autorzy:
    Ersoy, Bahri
    Çiftçi, Hakan
    Evcin, Atilla
    Merdivenci, Yılmaz
    Powiązania:
    https://bibliotekanauki.pl/articles/2146940.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    methacrylate copolymer
    zeta potential
    contact angle
    hydrophobicity
    surface free energy
    Opis:
    In this study, some electrokinetic and surface properties of MBAOM-GMA copolymers synthesized from 2-[(methoxy-1,3-benzothiazole-2-yl) amino]-2oxoethyl methacrylate (MBAOM) and glycidyl methacrylate (GMA) monomers were investigated. Accordingly, (i) pH-dependent zeta (ζ) potential changes of the copolymers were investigated under a constant ionic strength (in 1.10-3mol/dm3 NaCl) and the corresponding isoelectric points (iep) were determined, (ii) zeta potential changes depending on the salt concentration in the presence of mono-, di- and tri-valent metal salts were examined, (iii) contact angles (θ) of the copolymers with water were measured and their wetting behavior was assessed, and (iv) surface free energies (SFE) of the copolymers were determined by Acid-Base approach using Van Oss-Chaudhury-Good method. The compositions of the copolymers were 77% MBAOM - 23% GMA, 45% MBAOM - 55% GMA, and 19% MBAOM - 81% GMA. FeCl3, CaCl2, and KCl salts were used for the salt solutions for the zeta potential measurements. As a result, (i) it was determined that the chemical structure of methacrylate copolymers showed a decisive effect on both electrokinetic and surface properties, (ii) the hydrophobic character of copolymer increased with the increase of the GMA ratio, and correspondingly, the SFE decreased, and (iii) the iep of the copolymers varied between pH 3.1-3.7 depending on composition.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 5; art. no. 152162
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption of sodium/calcium poly(acrylic acid) salts on anatase: effect of the polyelectrolyte molecular weight and neutralization
    Autorzy:
    Jacquemet, Christian
    Powiązania:
    https://bibliotekanauki.pl/articles/1449765.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    adsorption
    free energy
    Langmuir isotherm
    sodium-calcium poly(acrylic acid) salts
    anatase
    Opis:
    Abstract: Interactions of poly(acrylic acid)s (PAAs) of two different molecular weights (Mw = 9,560 g×$mol^{-1}$ and 4,220 g×$mol^{-1}$) with surfaces of an untreated anatase $TiO_2$ were assessed through adsorption isotherm measurements. Those dispersants were tested under different sodium-calcium neutralization states (molar ratio $r = Ca^{2+}$ / $CO_{2-}$ varying from 0 to 0.35). Their behavior towards the $TiO_2$ surfaces can be described by the Langmuir adsorption model. For both polymers, surface coverage ($Γ_max$) evolves linearly with the molar ratio $r$. For a given r value, a lower surface coverage was observed with the polymer having the highest molecular weight. The free energy of adsorption ($/DeltaG_{ads}$) of PAAs was estimated from adsorption experiment data. This calculation indicates that sorption occurs spontaneously and is unlikely to be of chemical nature. The absolute values of $/DeltaG_{ads}$ are higher for the highest molecular weight polymers suggesting that they are more strongly adsorbed to anatase surfaces. The absolute values of $/DeltaG_{ads}$ per mole of sodium-calcium macromolecules are found to be lower than those calculated for their homologues 100% sodium neutralized suggesting that they are bound with the solid by a fewer number of segments.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2020, 56, 1; 113-123
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Surface free energy of extruded polymer compositions
    Autorzy:
    Garbacz, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/110140.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    extrusion process
    blowing agent
    antistatic agent
    wettability
    surface free energy
    adhesive properties
    Opis:
    Suitable adhesive properties of the polymer compositions provide largely outer surface of the product. The aim of the studies was evaluation of the efficiency of the extrusion process and physical properties of PVC modified by selected auxiliary. In the studies PVC was used. PVC was modified by blowing agent (0-1.5% by mass) and antistatic agent (0-0.8% by mass) in the form of polyvinyl chloride concentrates. Efficiency of extrusion process is determined also by selected proprieties of surface layer of a mill cake of polyvinyl chloride. Surface free energy has been calculated in Owens-Wendt method. Antistatic agent causes diminishing of wettability and adsorption of surface layer and eventually increase of surface free energy of surface layer. For ensuring appropriate adhesion properties of a surface layer it would be advisable to use, for polyvinyl chloride modification, the antistatic agent in the amount not smaller than 0.4% by mass in relation to polyvinyl chloride mass. Taking into account research results, which can be useful during the development of processing technology of the polyvinyl chloride used for polymers composites, it can be stated that the content of the blowing agent used, noticeably decreasing polymer mass and simultaneously not worsening the properties of a surface layer, should not exceed 0.5÷1.0% by mass in relation to polyvinyl chloride mass.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 6; 1509-1516
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wettability of quartz particles at varying conditions on the basis of the measurement of relative wetting contact angles and their flotation behaviour
    Autorzy:
    Gao, Shuling
    Ma, Lifeng
    Wei, Dezhou
    Shen, Yanbai
    Powiązania:
    https://bibliotekanauki.pl/articles/109832.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    relative wetting contact angle
    Washburn technique
    surface free energy
    flotation behaviour
    sodium oleate
    Opis:
    In this paper, on the basis of a modified Washburn equation, the squared incremental pressure due to liquid rising vs. time were measured instead of wicking distances before reaching equilibrium, and the relative wetting contact angles (RWCA) were applied to characterize the surface wettability of quartz particles conditioned at different concentrations of flotation reagents. Combined with the flotation experiments on quartz particles at corresponding conditions, the relationship between flotation recoveries and RWCA was analysed, which proves that RWCA can characterize the surface wettability of quartz particles accurately. The results also showed that the best reagent conditions for floating quartz are pH 12.0, a Ca2+ concentration of 1×10-3 mol/dm3 and a sodium oleate concentration of 0.75×10-3 mol/dm3, where the recovery of quartz is 86%. The surface tension of the filtrate of the pulp was determined by a fully-automatic tensiometer as well. Based on the measured values of RWCA and surface tension, the free energy changes (ΔG) before and after the adhesion of bubbles and particles per unit area at corresponding situations were calculated, respectively. The trends of ΔG varying with the concentrations of reagents were in close accordance with those of RWCA and the flotation recoveries, proving that it is more likely for particles having bigger contact angles to adhere to bubbles, resulting in a higher flotation recovery. These results give a more feasible and accurate approach to analysing the surface wettability and floatability of fine particles.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2019, 55, 1; 278-289
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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