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 Cr2O(4)(2-)/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, K-i(ex), 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, K-m = 1.5 x 10(-3) m/h and K(o)A(v) = 2.94 x 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.