Studying bubble–particle interactions by zeta potential distribution analysis

Abstract

Over the last decade, Xu and Masliyah have pioneered an approach to characterize the interactions between particles in dynamic environments of multicomponent systems by measuring zeta potential distributions of individual components and their mixtures. Using a Zetaphoremeter, the measured zeta potential distributions of individual components and their mixtures were used to determine the conditions of preferential attachment in multicomponent particle suspensions. The technique has been applied to study the attachment of nano-sized silica and alumina particles to sub-micron size bubbles in solutions with and without the addition of surface active agents (SDS, DAH and DF250). The degree of attachment between gas bubbles and particles is shown to be a function of the interaction energy governed by the dispersion, electrostatic double layer and hydrophobic forces. Under certain chemical conditions, the attachment of nano-particles to sub-micron size bubbles is shown to be enhanced by in-situ gas nucleation induced by hydrodynamic cavitation for the weakly interacting systems, where mixing of the two individual components results in negligible attachment. Preferential interaction in complex tertiary particle systems demonstrated strong attachment between micron-sized alumina and gas bubbles, with little attachment between micron-sized alumina and silica, possibly due to instability of the aggregates in the shear flow environment.

Heterocoagulation of alumina and quartz studied by zeta potential distribution and particle size distribution measurements

“…In the present work, as the pH increased from 4.7 to 10.6, the zeta potential of alumina steadily decreased from 33 to -38 mV, and the point of zero charge (pzc) for alumina in the present work was around 8.5, which is close to those reported by others (e.g., 8.0 -9.3) [14,[19][20][21], with the relative difference being smaller than 10%. The zeta potential of quartz kept negative and decreased from -23 to -49 mV as pH increased from 4.2 to 10.4, which is also consistent with the literature [14,16]. Overall, the zeta potential difference between alumina and quartz steadily decreased as the pH level changed from acidic to alkaline.…”

“…That alumina and quartz would carry opposite surface charges at acidic conditions can give rise to attractive electrostatic double layer force. As the attractive electrostatic double layer interaction is considered the main cause of heterocoagulation [4][5][6][7][15][16][17], the heterocoagulation between alumina and quartz is more likely to occur at acidic pHs.…”

“…It is difficult to tell which of the above interpretations is true based on zeta potential distribution measurement alone despite the fact that zeta potential distribution was extensively used to study the hetercogulation between different minerals [15][16][17][24][25][26]. Other information such as particle size distribution is expected to help understand the structure of the aggregates.…”

“…Where A 132 refers to the Hamaker constant, R 1 and R 2 refer to the radii of two spherical alumina and quartz particles, h is the distance between alumina and quartz surfaces, k B is the Boltzmann constant with value of 1.381×10 -23 J/K, T is the temperature in K (293.15 K in this work), ħ is the Planck constant with the value of 6.626×10 -34 J·s, ω is the characteristic relaxation frequency of the UV region with the value of 2.068×10 16 rad/s, n 1 , n 2 and n 3 represent the refractive indices of alumina, quartz and water, respectively, ε is the relative dielectric constant of the 0.1 mM NaCl solution with the value of 78.5, ε 0 is the permittivity of vacuum with the value of 8.854×10 -12 C 2 •m/J, ψ 1 and ψ 2 are the surface potentials of alumina and quartz, which are substituted by the measured zeta potential value, κ -1 is the Debye length (Eq.5) with the value of 30.4 nm in 0.1 mM NaCl solution [37], determined by equation (5) with the unit of nm for κ -1 , and mol/L for c NaCl , respectively. Fig.…”

CO2/N2 triggered switchable Pickering emulsions stabilized by alumina nanoparticles in combination with a conventional anionic surfactant

“…S3, † a little higher than that reported in the literature of 9.5. 52,53 This means that the particles are positively charged in pure water (pH ¼ 6.1). Although the particles have a primary diameter of 13 nm according to the supplier and the TEM image, they aggregate to some extent to give an average particle diameter of around 190 nm and a polydispersity of 0.12 at concentrations between 0.01 wt% and 0.1 wt% when dispersed ultrasonically in pure water (measured by light scattering, Fig.…”