An apparatus to measure electrical charge of bubble swarms

[Display omitted] ► Introduce device to measure charge on flotation size range of bubble swarms. ► In-process measurement of gas holdup, conductivity and bubble size distribution. ► Technique was validated comparing iep values available in literature. ► Measurements were performed in ionic/non-ionic surfactants and metal ions. ► Good agreement with established theory and prior experimental findings. An apparatus has been developed to characterize bubble charge by measuring the swarm potential of gas bubbles. The technique allows in-process measurement of all system variables associated with bubble surface electrical charge: swarm potential, solution conductivity, gas holdup, pH and bubble size distribution. The method was validated by comparing with literature iso-electric point (iep) values. Bubble swarm potential was measured as a function of concentration and pH for a series of non-ionic surfactant frothers, ionic surfactant collectors and multivalent metal ions. Results showed good agreement with established theory and prior experimental findings. The setup is a step towards measurement of charge on flotation size range of bubble swarms.