Fig. 10.

Results of chemical Cr pre-treatment experiments; (a) Cr³⁺ formation in 0.5 M HNO₃ and 3 wt% H₂O₂ as a function of time, and (b) formation of Cr(III)-Cl complexes at the expense of Cr³⁺ in hot (140°C) 10M HCl followed by immediate dilution with cold (5 °C) Milli-Q water to 0.5 M HCl and equilibration at room temperature as a function of time. Cr³⁺ and Cr(III)-Cl complexes were separated on an AG50w-x8 cation column according to the their distribution coefficients, K_D (Table 2).