Compressed air-assisted solvent extraction (CASX), was employed to remove Cr(VI) from synthetic wastewater and electroplating wastewater with the effects of pH, extractant=diluent ratio, solvent dosage, and competing anion concentration on Cr(VI) removal efficiency explored. The dosages required for Cr(VI) removal are dependent upon the speciation of Cr(VI) with molar ratio between Aliquat 336 and Cr(VI) of 1:1 and 2.8:1 for HCrO4- and CrO24-, respectively. Efficiency of Cr(VI) regeneration is influenced by pH and chloride ion concentrations. Based on the affinity order of HCrO4- > Cl- > CrO24- > OH- to Aliquat 336 concluded from this study, alternation of Cr(VI) species to CrO24- by raising solution pH up to 8 and addition of chloride (50 times more of Aliquat 336 dosage applied) can satisfy the Cr(VI) regeneration from the spent solvent phase.
Separation Science and Technology 44(16), pp.3911-3922