MODELING SURFACTANT REMOVAL IN FOAM FRACTIONATION .1. THEORETICAL DEVELOPMENT

Surfactant removal by foam fractionation was theoretically analyzed by treating surfactant mass transfer from a bulk solution onto a moving bubble as a convective diffusion process. A mathematical model express ing the removal rate as a function of pertinent parameters was develop ed. The parameters included superficial air velocity, bubble size, bub ble rising velocity, surfactant diffusion coefficient, and concentrati on. The model indicated that surfactant removal can be described as a first-order process whose rate increases with the diffusion coefficien t, the superficial air velocity and the surfactant concentration in th e bulk solution, but decreases with bubble size and bubble rising velo city. Based on the assumption of a completely mixed reactor within a s ection of a foam fractionator, a simplified model for foam fractionati on under batch operation conditions was also presented. This simplifie d model provides a theoretical basis according to which the diffusion coefficient of surfactants can be determined and the model itself can be verified with experimental data.