Effect of an Electric Field on Surface Properties of Hydrophobic Particles during a Flotation Process in Salt Water

Abstract

Under air flotation conditions, the effect of an electric field (EF) to the interfacial properties of hydrophobic particles in salt solution was investigated by using molecular dynamics simulation. The varieties of thickness of the hydrophobic layer on the surface of the hydrophobic particles, radial distribution function of Na + , diffusivity of CO 2 and H 2 O, residence time of H 2 O in the solvent shell of Na + , and the distribution of CO 2 near the graphene caused by the applied EF in different NaCl systems were calculated, and all those results were compared with those where there is no EF applied. The results reveal that the thickness of the hydrophobic layer near the hydrophobic particles is decreased under an EF. The coordination number and residence time of H 2 O in the solvent shell of Na + are also decreased, which indicates that the restraint of Na + on surrounding H 2 O is weakened, and the H 2 O molecules are more mobile. Under an external EF, the diffusion coefficient of CO 2 and H 2 O is increased, and the quantity of CO 2 near the surface of graphene is decreased according to the numerical results of the radial distribution of graphene−CO 2 . All the results indicate that the EF will decrease the thickness of the hydrophobic layer near hydrophobic particles, which can therefore weaken the adsorption between the hydrophobic particles and the gas molecules. The simulation results in the present study can provide theoretical support for brine mineral flotation under an external EF.

Screening of Green and Environmentally Friendly Deep Eutectic Solvents and Study on Molecular Mechanism and Process for Separation of Isopropanol and Cyclohexane

“…The radial distribution function (RDF) is introduced as the ratio of the area density to the system average density. The coordination number (CN) can be obtained by integrating the RDF as follows G normalA normalB ( r ) = false⟨ ρ normalB false( r false) false⟩ ⟨ ρ B ( r ) ⟩ l o c a l = 1 ⟨ ρ B ( r ) ⟩ l o c a l 1 N normalA ∑ i ∈ normalA N normalA ∑ j ∈ normalB N normalB δ ( r i j − r ) 4 π r 2 where A and B are two different particles in the system, N A and N B are the total amounts of A and B, respectively, ⟨ρ B ( r )⟩ is the number density of substance B surrounding substance A at a distance of r , ⟨ρ B ( r )⟩ local is the statistical average density of ⟨ρ B ( r )⟩ local , and the radius is r max , which is half of the shortest side of the box.…”

Emerging Trends of Computational Chemistry and Molecular Modeling in Froth Flotation: A Review

“…The MD method has also demonstrated its ability to simulate the effect of an external electric field on water/mineral/gas interfaces. − Air flotation of hydrophobic particles immersed in saline solutions with different concentrations of NaCl and in the presence of an electric field shows that the latter would deteriorate the adhesion of bubbles to hydrophobic particles. The application of an external electric field could also lead to a reduction in the size of the bubbles, thus promoting better attachment of hydrophobic particles during flotation .…”