Fig. 11. (A) Breakthrough curves for four column ion exchange runs (C = concentration of the effluent, C0 = initial Cr2O72– concentration = 6 ppm, pH ∼ 3, flow rate 1 mL min–1, one bed volume = 3.5 mL, stationary phase MOR-1–A/sand = 0.05 : 5 g). (B) Total Cr concentration vs. bed volume (each bed volume = 3.5 mL) of natural spring water, to which trace Cr(vi) was added (initial total Cr concentration ∼ 450 ppb, pH adjusted to 3), after passing the solution through an ion-exchange column of MOR-1–A/sand (0.05 : 5 g).
