An investigation into the mechanism of the three-phase contact formation at fluorite surface by colliding bubble

Zawała, Jan; Drzymala, Jan; Małysa, K.

doi:10.1016/j.minpro.2008.06.006

Cited by 41 publications

(16 citation statements)

References 39 publications

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“…These results are in conformity with previous reported data for the BSA foam films (Yampolskaya and Platikanov 2006). Hydrophobicity of solid surface and electric surface charge of the interacting interfaces are the factors of major importance for stability of the wetting films formed by the colliding bubble and the three phase contact (TPC) formation Zawala et al 2008). Mica is a perfectly smooth and hydrophilic solid surface (water contact angle is zero) and there is no TPC formation in distilled water because the wetting film is stable.…”

Section: Equilibrium Microscopic Foam Filmssupporting

confidence: 92%

Influence of pH of the BSA solutions on velocity of the rising bubbles and stability of the thin liquid films and foams

et al. 2010

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Influence of pH of the BSA solutions on velocity of the rising bubbles, stability of foams, and properties of single foam and wetting films was studied. It was found that the solution pH affected significantly the BSA surface activity and properties of the protein adsorption layer under dynamic and static conditions. At pH close to the isoelectric point (pH IEP = 4.8) the BSA showed the highest surface activity. The equilibrium microscopic foam films of thicknesses of 64-80 nm, depending on the BSA concentration, were obtained at pH = 5.8. Under dynamic conditions the bubble rising velocity was reduced in a highest degree and the foam formed were most stable at the solutions pH-5.8 and 4.8. Lowering the bubble velocity shows that the BSA adsorption layer was formed, which retarded fluidity of the bubble surface. When the solution pH was significantly lower (pH = 3.9) or much higher (pH = 10) than the pH IEP then the BSA practically had no influence on the bubble velocity and the foam stability was drastically reduced. Moreover, the pH variations affected also the time of the threephase contact (TPC) formation on mica surface covered by the BSA adsorption layers. These pH dependent changes in the BSA surface activity indicate that the BSA linear conformers, existing at pH far away from the pH IEP , have much higher affinity to aqueous phase resulting from higher net electrical charge present over the extended BSA molecule conformers.

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Section: Equilibrium Microscopic Foam Filmssupporting

confidence: 92%

Influence of pH of the BSA solutions on velocity of the rising bubbles and stability of the thin liquid films and foams

et al. 2010

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“…At neutral pH, the VSFG signal vanished, indicating a more random orientation of the interfacial water molecules at a near-neutral surface. Water contact angle θ C measurements on calcium fluoride (111) surfaces for several pH conditions confirm this behavior, where θ C is nonzero only for near-neutral pH values [74].…”

Section: Hydrated Surfacesmentioning

confidence: 68%

“…Our results agree with previous ab initio calculations at the same level of theory [3] and with water contact angle measurements. The latter suggest a partial hydrophobic character of (111) fluorite terminations [30,74]. The average adsorption energy at the (111)-water interface is very close to the condensation energy of water, which is between −45 kJ/mol and −35 kJ/mol for temperatures ranging from 0°C to 200°C.…”

Section: Adsorption Energiesmentioning

confidence: 74%

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Surface reconstruction of fluorites in vacuum and aqueous environment

Fisicaro

Sicher

Amsler

et al. 2017

Phys. Rev. Materials

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Surfaces and interfaces of bulk materials with liquids are of importance for a wide range of chemical processes.In this work, we systematically explore reconstructions on the (100) surface of calcium fluoride (CaF 2 ) and other fluorites (MF 2 ), M = {Sr,Cd,Ba} by sampling the configurational space with the minima hopping structure prediction method in conjunction with density functional theory calculations. We find a large variety of structures that are energetically very close to each other and are connected by very low barriers, resulting in a high mobility of the topmost surface anions. This high density of configurational states makes the CaF 2 (100) surface a very dynamic system. The majority of the surface reconstructions found in CaF 2 are also present in SrF 2 , CdF 2 , and BaF 2 . Furthermore, we investigate in detail the influence of these reconstructions on the crystal growth of CaF 2 in solvents by modeling the fluorite-water interface and its wetting properties. We perform a global structural search both by explicitly including water molecules and by employing a recently developed soft-sphere solvation model to simulate an implicit aqueous environment. The implicit approach correctly reproduces both our findings with the explicit-water model and the experimentally reported contact angles for the partial-hydrophobic (111) and hydrophilic (100) surfaces. Our simulations show that the high anion mobility and the low coordination of the (100) surface atoms strongly favors the adsorption of water molecules over the (111) surface. The aqueous environment makes terminations with low-coordination surface atoms more stable, promoting (100) growth instead of the (111).

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“…Xia et al [28] found that the natural wettability of both natural and gold coated coal surfaces is directly affected by its surface roughness. Zawala et al [29] found that larger roughness and irregularities of the fluorite surface can shorten the time of the liquid/gas/solid three-phase contact formation by colliding bubbles. In our investigation, we concluded that the rough fluorite surface (PF) could provide more active sites for NaOL adsorption than the smooth fluorite surface (CF), which agrees with the results obtained for NaOL adsorption on the fluorite surface.…”

Section: Surface Topographic Analysesmentioning

confidence: 99%

Flotation Behavior of Different Colored Fluorites Using Sodium Oleate as a Collector

et al. 2017

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Using sodium oleate (NaOL) as a collector, the flotation characteristics of natural colorless fluorite (CF), green fluorite (GF), and purple fluorite (PF) were investigated through micro-flotation tests, collector adsorption measurements, and surface tension measurement. The micro-flotation results indicated that CF had a much better flotation response than both GF and PF, and had higher floatation recovery. The results demonstrated a considerable discrepancy in the interfacial properties between colorless and colored fluorite, even though all the samples were obtained from the same deposit, holding a similar high purity of CaF 2 . The adsorption capacity of CF, GF, and PF for NaOL was 2.27, 4.18, and 8.21 × 10 −6 mol/g under neutral conditions, respectively. Fourier transform infrared (FT-IR) measurements revealed that the carboxyl groups of NaOL reacted with Ca sites on the surface of fluorites by chemical adsorption. From the zeta potential analyses, PF exhibited a lower positive potential than CF and GF, mainly due to its surface carbonation. In the presence of NaOL, the surface potential of fluorites changed from positive to negative because the NaOL collector had been adsorbed onto the mineral surface and changed their surface potential, which was consistent with the flotation results at different pH values. We found that the floatability of the fluorite samples was influenced by their surface roughness, measured by an atomic force microscope (AFM) and scanning electron microscope (SEM). PF can be floated with adding more reagent dosage than CF and GF to compensate for its higher surface roughness.

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An investigation into the mechanism of the three-phase contact formation at fluorite surface by colliding bubble

Cited by 41 publications

References 39 publications

Influence of pH of the BSA solutions on velocity of the rising bubbles and stability of the thin liquid films and foams

Influence of pH of the BSA solutions on velocity of the rising bubbles and stability of the thin liquid films and foams

Surface reconstruction of fluorites in vacuum and aqueous environment

Flotation Behavior of Different Colored Fluorites Using Sodium Oleate as a Collector

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