Chromium (III) removal from aqueous solution applying bulk liquid membrane using tri-n-butyl phosphate (TBP) as a mobile carrier

Abstract

The separation of chromium (III) ions from aqueous solutions using bulk liquid membrane (BLM) process has been studied, in this techniques kerosene chosen as organic solvent and tri-n-butyl phosphate (TBP) as mobile carrier. BLM extraction was tested by varying the pH of the feed phase in range (2-6), TBP carrier concentration in range (10-40% (v/v)), H₂SO₄ concentration of stripping phase in range (0.25-1M), the initial concentration of the feed phase in range (100-400 mg/l), and agitation speed in range (100-300 rpm) to find the best operating conditions to reach maximum recovery of chromium (III) ions.The transfer kinetics was inspected using a kinetic model including two consecutive irreversible first-order reactions were the maximum extraction (E%) and stripping (S%) efficiencies achieved of chromium (III) ions were 93.6% and 93.2% respectively. The rate constants of the extraction and stripping processes (k₁ and k₂), transport fluxes of ions across the BLM (J_f^max, J_s^max) and time dependency of the process (t_max) of maximum solute concentrations in membrane (R_m^max) were determined and discussed. Results proved that the k₁ and k₂ had increased with the increasing acidity of donor phase and time required to reach steady state (t_max) decreased. The transport rate of Cr (III) ion had increased with the increasing of TBP concentration, transport rate decreased with increased initial feed phase concentration and was increased with increasing agitation speed.