The effect of temperature and dissolved organic components on the film thinning between droplets and bubbles

Treatment of produced water (PW) is a major issue in the petroleum industry and gas flotation is an efficient treatment method that relies on the generation of gas bubbles and their attachment to oil droplets. Formation of an oil film over the gas bubbles provides stable aggregates, and quick attachment is a key-step for efficient gas flotation. Here we investigated how the temperature and the dissolved organic components in the water phase influenced the film thinning process between approaching droplets and bubbles using a microfluidic method. Information about drop-bubble attachment times, bubble-bubble coalescence times, and size distributions of drops and bubbles were retrieved by image analysis. The dissolved components stabilized the gas bubbles through adsorption at the interface. This slowed down the film thinning and prolonged the bubble coalescence and drop-bubble attachment times. Increasing the temperature reduced the drainage times due to reduced viscosity. In all cases bubble coalescence was faster than drop-bubble attachment. The results were discussed in view of previous gas flotation studies and the oil removal trends agreed well with the trends observed for film thinning processes.