Different behavior of bovine serum albumin as foaming agent in foam enrichment of Rhodamine 6G and Evans blue

As a classic foaming agent, bovine serum albumin (BSA), can be adsorbed on gas-liquid interface to generate stable foam. In the present study, the foam disappeared when Evans Blue (EB) interacted with BSA. Therefore, this phenomenon was used to separate the non-defoaming Rhodamine 6G (R6G) from the defoaming EB. After optimizing the parameters such as BSA concentration, pH and gas flow rate, R6G was enriched with spilled foam. The enrichment ratio and recovery of R6G were 5.32 and 88.29%, respectively, in pH 7 solution at a gas flow rate of 0.25 mL/min using 0.20% BSA as foaming agent. The present strategy provides an effective method for foam separation and dye recycling.