A visualizing method for study of micron bubble attachment onto a solid surface under varying physicochemical conditions

The impinging jet technique, a direct microscopic observation method, is pr esented to fundamentally study micron bubble attachment onto a solid surfac e (collector) under well-controlled stagnation flow conditions. The bubble- collector attachment near the stagnation point of an impinging jet is analo gous to bubble-fine solid interaction, which is of interest to flotation pr ocesses. In this work, bubble attachment experiments were conducted for sod ium chloride solutions with various concentrations (10(-1)-10(-4) M) and pH values (2.5-9.0) under a fixed flow intensity tin terms of Reynolds number Re = 200). In addition; the effect of metal ion valence on the bubble atta chment was examined as well. Results have showed that the bubble attachment flux was dependent on both solution concentration (ionic strength) and pH, suggesting a strong impact of the electrostatic double layer interaction. In the presence of multivalent metal ions, the bubble attachment rate was n oticeably enhanced.