scholarly journals Application of Depletion Attraction in Mineral Flotation: II. Effects of Depletant Concentration

Minerals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 450 ◽  
Author(s):  
Gahee Kim ◽  
Junhyun Choi ◽  
Sowon Choi ◽  
KyuHan Kim ◽  
Yosep Han ◽  
...  
Keyword(s):  
Surface Tension ◽  
Polymer Brush ◽  
Bubble Surface ◽  
Mass Ratio ◽  
Attraction Force ◽  
Surface Acting ◽  
Pure Silica ◽  
Mineral Flotation ◽  
Air Water Interface ◽  
High Concentrations

Along with the accompanying theory article, we experimentally investigate the effect of the depletion attraction force on the flotation of malachite. While varying the concentration of the depletion agent (polyethylene glycol), three different systems are studied: pure malachite, pure silica and a 1:1 mass ratio of malachite and silica binary system. We find that the recovery increases significantly as the concentration of the depletion reagents increases for all three systems. However, the recovery suddenly decreases in a certain concentration range, which corresponds to the onset of the decreased surface tension when high concentrations of the depletion agent are used. The decreased surface tension of the air/water interface suggests that the recovery rate is lowered due to the adsorption of the depletion agent to the bubble surface, acting as a polymer brush. We also perform experiments in the presence of a small amount of a collector, sodium oleate. An extremely small amount of the collector (10−10–10−5 M) leads to the increase in the overall recovery, which eventually reaches nearly 100 percent. Nevertheless, the grade worsens as the depletant provides the force to silica particles as well as target malachite particles.

Surfactant Impurities Can Explain the Jones-Ray Effect

2018 ◽  
Author(s):  
Timothy Duignan ◽  
Marcel Baer ◽  
Christopher Mundy
Keyword(s):  
Surface Tension ◽  
Electrostatic Potential ◽  
Driving Forces ◽  
Salt Water ◽  
Fundamental Property ◽  
Apparent Contradiction ◽  
Low Salt ◽  
Air Water Interface ◽  
Added Salt ◽  
Effect Of Surface

<div> <p> </p><div> <div> <div> <p>The surface tension of dilute salt water is a fundamental property that is crucial to understanding the complexity of many aqueous phase processes. Small ions are known to be repelled from the air-water surface leading to an increase in the surface tension in accordance with the Gibbs adsorption isotherm. The Jones-Ray effect refers to the observation that at extremely low salt concentration the surface tension decreases in apparent contradiction with thermodynamics. Determining the mechanism that is responsible for this Jones-Ray effect is important for theoretically predicting the distribution of ions near surfaces. Here we show that this surface tension decrease can be explained by surfactant impurities in water that create a substantial negative electrostatic potential at the air-water interface. This potential strongly attracts positive cations in water to the interface lowering the surface tension and thus explaining the signature of the Jones-Ray effect. At higher salt concentrations, this electrostatic potential is screened by the added salt reducing the magnitude of this effect. The effect of surface curvature on this behavior is also examined and the implications for unexplained bubble phenomena is discussed. This work suggests that the purity standards for water may be inadequate and that the interactions between ions with background impurities are important to incorporate into our understanding of the driving forces that give rise to the speciation of ions at interfaces. </p> </div> </div> </div> </div>

From Surface Tension to Molecular Distribution: Modeling Surfactant Adsorption at the Air–Water Interface

Langmuir ◽  
2021 ◽  
Vol 37 (7) ◽  
pp. 2237-2255 ◽  
Author(s):  
Mengsu Peng ◽  
Timothy T. Duignan ◽  
Cuong V. Nguyen ◽  
Anh V. Nguyen
Keyword(s):  
Surface Tension ◽  
Surfactant Adsorption ◽  
Water Interface ◽  
Molecular Distribution ◽  
Distribution Modeling ◽  
Air Water Interface

Production and Properties of Biosurfactants from a Newly Isolated Pseudomonas fluorescens HW-6 Growing on Hexadecane

2006 ◽  
Vol 61 (7-8) ◽  
pp. 553-559 ◽  
Author(s):  
Evgenia Vasileva-Tonkova ◽  
Danka Galabova ◽  
Emilia Stoimenova ◽  
Zdravko Lalchev
Keyword(s):  
Pseudomonas Fluorescens ◽  
Industrial Wastewater ◽  
High Surface ◽  
Emulsifying Properties ◽  
Effective Surface ◽  
Mineral Oils ◽  
Air Water Interface ◽  
Polluted Sites ◽  
High Concentrations ◽  
High Surface Activity

The newly isolated from industrial wastewater Pseudomonas fluorescens strain HW-6 produced glycolipid biosurfactants at high concentrations (1.4-2.0 g l-1) when grown on hexadecane as a sole carbon source. Biosurfactants decreased the surface tension of the air/ water interface by 35 mN m-1 and possessed a low critical micelle concentration value of 20 mg l-1, which indicated high surface activity. They efficiently emulsified aromatic hydrocarbons, kerosene, n-paraffins and mineral oils. Biosurfactant production contributed to a significant increase in cell hydrophobicity correlated with an increased growth of the strain on hexadecane. The results suggested that the newly isolated strain of Ps. fluorescens and produced glycolipid biosurfactants with effective surface and emulsifying properties are very promising and could find application for bioremediation of hydrocarbon-polluted sites.

Surface active properties at the air–water interface of β-casein and its fragments derived by plasmin proteolysis

1989 ◽  
Vol 56 (3) ◽  
pp. 487-494 ◽  
Author(s):  
Michael Wilson ◽  
Daniel M. Mulvihill ◽  
William J. Donnelly ◽  
Brian P. Gill
Keyword(s):  
Surface Tension ◽  
Water Interface ◽  
Active Protein ◽  
Drop Volume ◽  
V Protein ◽  
Proteose Peptone ◽  
Rate Determining Step ◽  
Surface Active Properties ◽  
Air Water Interface ◽  
Surface Active

Summaryβ-Casein, was enzymically modified by incubation with plasmin to yield γ-caseins and proteose peptones. Whole γ-, γ1-, γ2/γ3-caseins and whole proteose peptone (pp) were isolated from the hydrolysate mixture. The time dependence of surface tension at the air-water interface of solutions of β-casein and its plasmin derived fragments, at concentrations of 10−1 to 10−4% (w/v) protein, pH 7.0, was determined, at 25 °C, using a drop volume apparatus. The ranking of the proteins with respect to rate of reduction of surface tension, during the first rate determining step, at 10-2% (w/v) protein, was γ2/γ3 ≫ pp > whole γ- > γ1- > β-casein. The ranking of the proteins with respect to surface pressures attained after 40 min (π40) was concentration dependent. γ2/γ3-Caseins were found to be very surface active, decreasing surface tension rapidly and giving a high π40. γ1 Casein decreased surface activity somewhat faster than β-casein, but generally reached a lower π40. Whole γ-casein reflected the properties of both γ1 and γ2/γ3-caseins. Proteose peptone was found to decrease surface tension rapidly during the initial rate determining step; it gave a relatively high π40 at a bulk phase concentration of 10−3% (w/v) protein, but, it was the least surface active protein at 10−1 and 10−2% (w/v) protein.

scholarly journals Effect of a surface tension gradient on the slip flow along a superhydrophobic air-water interface

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Dong Song ◽  
Baowei Song ◽  
Haibao Hu ◽  
Xiaosong Du ◽  
Peng Du ◽  
...  
Keyword(s):  
Surface Tension ◽  
Slip Flow ◽  
Surface Tension Gradient ◽  
Water Interface ◽  
Air Water Interface

Observations on the locomotion of post-larval and juvenile flying fish

1990 ◽  
Vol 70 (2) ◽  
pp. 311-320 ◽  
Author(s):  
John Davenport
Keyword(s):  
Surface Tension ◽  
Surface Roughness ◽  
Reynolds Numbers ◽  
Maximum Speed ◽  
Tail Flick ◽  
Horizontal Distance ◽  
Water Interface ◽  
Flying Fish ◽  
Air Water Interface ◽  
Air Penetration

Post-larval specimens of Hirundichthys affinis are capable of jumping out of water, but the pectoral and pelvic fins are not extended when in air. Penetration through the air/ water interface demands a force to overcome surface tension which is similar in magnitude to the force required for the jump itself. However, post-larvae do not produce the single propulsive tail flick which powers the jump until most of the animal has passed through the interface. The post-larva emerges at an angle close to 45°, thus maximising the horizontal distance travelled before re-entry.Whether swimming slowly (4 body lengths s-1), or at maximum speed (36 body lengths s-1), post-larvae swim with the pectoral and pelvic fins extended. Calculations show that fast swimming post-larvae operate at Reynolds’ numbers of about 4×103, where surface roughness and projections decrease rather than increase drag.

Influence of pH on the surface and foaming properties of aqueous silk fibroin solutions

Soft Matter ◽  
2020 ◽  
Vol 16 (15) ◽  
pp. 3695-3704 ◽  
Author(s):  
Xiuying Qiao ◽  
Reinhard Miller ◽  
Emanuel Schneck ◽  
Kang Sun
Keyword(s):  
Surface Tension ◽  
Silk Fibroin ◽  
Bubble Coalescence ◽  
Foaming Properties ◽  
Water Interface ◽  
Interfacial Layers ◽  
Air Water Interface ◽  
Influence Of Ph

Silk fibroin (SF) adsorbs at the air/water interface, reduces the surface tension, and forms interfacial layers suppressing bubble coalescence and stabilizing foam.

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