Separation and Recovery of Anionic Pollutants by the Emulsion Pertraction Technology. Remediation of Polluted Groundwaters with Cr (VI)

Polluted groundwaters with an average anionic composition of 9 mol Cr2O42-/m^3, 64 mol SO42-/m^3, and 9.2 mol Cl-/m^3 were treated by the emulsion pertraction technology using Alamine 336 as the extractant and NaOH as the stripping agent, to reduce the concentration of chromate compounds and recover them in a concentrated solution. A careful experimental design was carried out to analyze the equilibrium and kinetic behavior of the separation system. The equilibrium parameters of the chemical reactions involved, Kiex, were calculated from the experimental data. A mathematical model that described the kinetics of the separation and concentration processes was developed, and the unknown model parameters, that is, the membrane and the organic phase mass transport coefficients, Km = 1.5 × 10^-3 m/h and KoAv = 2.94 × 10^4 h^-1, were estimated. Within experimental system the kinetic control is shared between the internal (feed phase) and the membrane mass transport resistances.