The presence of oxygen molecules dissolved in aqueous
solutions is assumed to serve as a possible electron scavenger
competing with Cr(VI) for electrons, but experiments were
carried out by passing air and N2 into the solution at pH 0.5.
It was found that the gaves had no influence on the formation
of Cr(III) in the acidic solution. Similar experimental results
were reported by Borgarello et al. [28].
As concluded above, in this experiment the optimum operational
conditions are: pH 0.5; TiO2 dosage of 4 g l−1; initial
Cr(VI) concentration of 0.01 mol l−1; temperature 80 ◦C.