Generation and characterization of submicron size bubbles

A baffled high intensity agitation (BHIA) cell was used to generate submicron size bubbles of an average diameter around 500nm by hydrodynamic cavitation. The generation of submicron size bubbles by BHIA cell was found to be largely dependent on the agitation speed of impellers. The duration of agitation and temperature showed only a marginal effect on generation of submicron size bubbles. Surface properties such as zeta-potential and stability of submicron size bubbles were found to be highly dependent on the chemistry of solutions in which the bubbles are generated. The presence of surfactant and frother in water was found to be beneficial for generating a larger number of submicron size bubbles that are more stable, having a life time of up to 24h. Characteristics of submicron size bubbles generated by hydrodynamic cavitation in SDS (a) and DF250 (b) solutions at pH 8.5. [Display omitted] ► Review of current methods for nanobubble generation. ► Successful generation of stable submicron size bubbles by hydrodynamic cavitation. ► Submicron size bubbles stable for at least 24 h in frother or surfactant solutions. ► Fine tune of surface charge of submicron size bubbles by solution chemistry. ► Specific adsorption of calcium on CO2 bubbles, but not on air/water vapour bubbles.