Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Shinnosuke Usui is active.

Publication


Featured researches published by Shinnosuke Usui.


Journal of Colloid and Interface Science | 1973

Interaction of electrical double layers at constant surface charge

Shinnosuke Usui

Abstract The energy of interaction between two dissimilar double layers at constant surface charge V σ has been calculated by means of the linear (Debye-Huckel) approximation and compared with the energy of interaction at constant surface potential V ψ . The difference between V σ and V ψ becomes significant when the distance of grain separation becomes small. In the case where the surface potentials ψ 01 and ψ 02 are of the same sign and different in magnitude the V σ is always positive in contrast to V ψ , i.e., no potential maximum occurs. In the case where ψ 01 and ψ 02 are of opposite signs and different in magnitude the interaction changes from attraction to repulsion at a particular condition depending upon ψ 01 , ψ 02 and κ (the Debye-Huckel reciprocal length parameter). V σ for identical double layers has also been derived, and discussed by comparing with Frens and Overbeeks equation.


Journal of Colloid and Interface Science | 1978

Zeta potential measurements of bubbles in aqueous surfactant solutions

Shinnosuke Usui; Hiroshi Sasaki

Abstract The Dorn effect, or the sedimentation potential created when finely divided argon gas bubbles are allowed to rise through an aqueous solution, was measured under various conditions. The sedimentation potential was found to be proportional to the volume fraction of gas bubbles depending upon the surfactant involved and the specific conductances of the solutions. The zeta potentials of bubbles in aqueous solutions of sodium hexadecyl sulfate (SHS) and hexadecyltrimethylammonium bromide (HTAB) are given as a function of surfactant concentrations ranging from 10−7 to 10−5 M. Zeta potentials of bubbles in solutions of nonionic surfactants, such as polyoxyethylene dodecyl ether or 1-butanol, and in a mixture of these with SHS and HTAB, respectively, are also given. Electrokinetic adsorption densities of SHS or HTAB at moving bubble surfaces were calculated from zeta potentials using the Gouy—Chapman theory and were compared with data available in the literature that were obtained under equilibrium conditions. The former are always smaller than the latter over the concentration range tested.


Journal of Colloid and Interface Science | 1981

The dependence of zeta potential on bubble size as determined by the dorn effect

Shinnosuke Usui; Hiroshi Sasaki; H Matsukawa

Abstract The Dom potential caused by the rising of finely divided argon gas bubbles was measured by varying the bubble size in 1 × 10−6 and 1 × 10−5 M sodium hexadecyl sulfate (SHS), 1 × 10−2 M butanol aqueous solutions, and distilled water, respectively. The calculated values of negative zeta potentials increased with decreasing bubble size in each system. In contrast, no dependency of the zeta potential on particle size of glass beads was indicated, as expected from the theory. Electrokinetic adsorption densities of SHS calculated from zeta potentials extrapolated to zero bubble diameter were fairly close to the literature values for the same surfactant at the air-water interface, obtained under equilibrium conditions. The same procedure was applied to the butanol solution and distilled water systems in order to obtain the electrokinetic adsorption density of OH- ions. The relationship of the ratio Q Δ H (Q is the gas flow rate and ΔH is the increment of the liquid column height upon introduction of argon gas) to the mean diameter of gas bubbles was examined and compared with the photographic method.


Journal of Colloid and Interface Science | 1969

Adhesion of mercury and glass in aqueous solutions

Shinnosuke Usui; Taro Yamasaki

Abstract Attachment of a mercury droplet to a glass foil in aqueous KF solutions was investigated in the range of 10−3 to 10−1 M concentration at various polarization potentials of mercury. The relation between critical potentials of attachment and solution concentrations below 1.5 × 10−1 M was explained quantitatively by the theory of heterocoagulation of dissimilar particles. Deviations from the theory were found in the concentrations higher than 1.5 × 10−1 M. Critical potentials of detachment were also determined as a function of the concentration. A possible explanation was given for the weakened attachment at high salt concentration by considering the additional repulsion detected when the glass and mercury were close by. Some discussions were also given as the Hamaker constant for dissimilar substances immersed in a liquid medium.


Journal of Colloid and Interface Science | 1990

Effect of adsorbed layers on the van der Waals interaction between particles and bubbles in aqueous media

Shinnosuke Usui; Eytan Barouch

Abstract The effect of adsorbed layers on van der Waals interactions between alumina particles and bubbles in aqueous media was investigated. This system is important in flotation studies. In the absence of adsorbed layers, the interaction shows repulsion. When the alumina particles and bubbles are covered with adsorbed layers, the interaction energy changes from repulsion to attraction at small separations. The Vold and Lifshitz equations for a planar case yielded nearly identical results. However, when the interacting particles are spheres, certain differences have been obtained using the two approaches. It has been shown that the effect of adsorbed layers on the van der Waals energy is less significant than the hydrophobic interaction reported in the literature.


Colloids and Surfaces | 1987

Adsorption of dodecylammonium ion on quartz in relation to its flotation

S. Takeda; Shinnosuke Usui

Abstract The flotation of −10μm diameter quartz particles using dodecylammonium acetate (DAA) as a collector was carried out at pH 5 and pH 9.8 by varying DAA concentration. The adsorption density of DAA and the zeta potential of quartz were also measured in order to analyze the flotation results. At pH 5, complete flotation of quartz was achieved at a DAA adsorption density of only about 1% surface monolayer coverage, while at pH 9.8 the complete flotation of quartz required the adsorption density of DAA to be more than equivalent monolayer adsorption. The isoelectric point of quartz in the presence of DAA at pH 5 was best described by adopting Δp K (=p K − −p K + ) = 6, where K − and K + are the dissociation constants of anionic and cationic sites on quartz surfaces, respectively. Analysis of the results of zeta potential measurements at pH 9.8 on the basis of the site dissociation model suggests that the adsorbed species on quartz surfaces are dominated by undissociated free amine molecules at this pH. The mechanism of the free amine adsorption on fine quartz in alkaline media is discussed.


Journal of Colloid and Interface Science | 1991

ζ potential measurement by means of the plane interface technique

Hiroshi Sasaki; Atsushi Muramatsu; Hiroshi Arakatsu; Shinnosuke Usui

Abstract The ζ potential of quartz and sapphire plates in contact with aqueous solutions was measured by means of the plane interface technique, which involves establishing the liquid flow velocity—depth profile using reference (polystyrene latex) particles. The electroosmotic velocity obtained by extrapolation of the velocity profile to the cell wall permits calculation of the ζ potential of the cell wall—solution interface. The plane interface technique was also used to obtain the ζ potential at aqueous sodium dodecyl sulfate (SDS) solution surfaces with an open cell in which the upper boundary consists of an air—solution interface and the lower boundary, a quartz—solution interface. It was essential to eliminate the meniscus in the open cell to obtain normal velocity profiles. The ζ potential of the aqueous SDS solution surface paralleled the Stern potential, calculated from the surface tension—SDS concentration data by use of Gibbs adsorption equation and Gouy-Chapman theory, though the former was larger in magnitude than the latter.


Colloids and Surfaces | 1986

Attachment between mercury and argon bubbles in aqueous KF solutions

Shinnosuke Usui; H. Sasaki; F. Hasegawa

Abstract The attachment between mercury and argon bubbles in aqueous solutions was studied using a mercury electrode by varying the polarization potential of mercury and the KF concentration (5 × 10 −4 -1 M ). The polarization potential of mercury was converted into the potential of the Stern plane, ψ δ . There were two critical potentials, negative ψ − δ and positive ψ + δ , between which mercury and single bubbles show spontaneous attachment upon contact. In a more negative potential range than ψ − δ , there was strong repulsion, while in a more positive potential range than ψ + δ , repulsion was relatively weak. The negative values of ψ − δ decreased with increasing KF concentration with a sign reversal at KF concentrations higher than 1 × 10 −2 M , and the positive values of ψ + δ also decreased with increasing KF concentration; the range of ψ δ of mercury for spontaneous attachment became narrow with increasing KF concentration, that is the lower the concentration the easier the attachment, in contrast to the prediction of the colloid stability theory. The trend of ψ − δ in a dilute KF concentration range ( −2 M ) was interpreted in terms of the heterocoagulation theory with the negative Hamaker constant for mercury—bubble in water. Zeta potentials (ζ B ) of bubbles in aqueous KF solutions assessed using ψ − δ with the aid of the heterocoagulation theory showed anomalous behavior at high KF concentrations.


Colloids and Surfaces | 1988

Interaction between a stationary mercury electrode and a hydrogen bubble in an aqueous sodium dodecyl sulphate solution

M. Kaisheva; Shinnosuke Usui; Dai Qi

Abstract The stability and rupture of thin liquid films formed from an aqueous solution of Na 2 SO 4 (0.05 mol dm −3 ) in the presence of 5 × 10 −5 mol dm −3 sodium dodecyl sulphate between a stationary mercury electrode and a hydrogen bubble has been investigated as a function of electrode potential. The electrostatic component of disjoining pressure has been calculated using the results of capacity measurement for the mercury-solution interface. Special attention has been paid to films formed on positively charged mercury surfaces. In this case, despite the positive electrode polarization, the outer Helmholtz plane potential is found to be negative due to the high surface activity of the dodecyl sulphate anion. The van der Waals component of disjoining pressure has been calculated on the basis of a double sheath model of the two interacting surfaces, taking into consideration the orientation of the adsorbed surfactant layers at the interfaces. Calculations of the total disjoining pressure can explain film stability at negative mercury potentials, but do not explain film rupture when the polarization of the mercury is positive. The existence of a hydrophobic attractive interaction is postulated in the latter case.


Colloids and Surfaces | 1988

Cationic flotation of quartz from an artificial mixture with hematite using hexylamine

S. Takeda; Shinnosuke Usui

Abstract The cationic flotation of quartz was carried out from an artificial mixture (1:1 by weight) of fine grained ( − 10 μm) quartz and hematite, using hexylamine acetate (HAA) and dodecylamine acetate (DAA) as collectors. Selective flotation of quartz was possible in the pH range 9–10 using HAA. The adsorption densities of DAA and HAA on quartz and hematite were measured at pH 9.8 and the relationship between the flotation behavior of both minerals and the surface coverage of collectors was established. Complete flotation of quartz and hematite required a surface coverage (θ) of DAA of about 100% at pH 9.8, while complete flotation of quartz took place at θ ⋍ 10% with HAA. The flotation behavior with DAA was explained by considering the adsorption of undissociated free amine. Zeta potential measurements were incorporated to interpret the difference in the adsorption behavior of both collectors on quartz and hematite.

Collaboration


Dive into the Shinnosuke Usui's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge