To clarify adsorption-equilibrium relationship at liquid-atmosphere interface, adsorption behavior of bisphenol-A (BPA) and diethyl phthalate (DEP) onto bubble surface was studied by using nonfoaming adsorptive bubble separation (NFBS) technique. The adsorption isotherms of BPA and DEP were obtained experimentally. The experimental results showed that adsorption equilibrium of BPA and DEP on bubble surface followed Langmuir's adsorption isotherm. Two adsorption parameters, the adsorption equilibrium constant and the saturated adsorption density on bubble surface could be determined and were 2.04 x 10(5) cm(3)/g and 1.35 x 10(-8) g/cm(2) for BPA and 9.41 x 10(4) cm(3)/g and 1.79 x 10(-8) g/cm(2) for DEP, respectively. (C) 2007 Elsevier B.V. All rights reserved.