Continuous adsorption of Pt ions in a batch reactor and packed-bed column

Continuous adsorption of platinum (Pt) was performed by using a batch reactor and a packed-bed column system in which amine-treated activated carbon (AC) pellets (Norit RO 0.8) were used as adsorbents. The feed solution (pH 2.0) contained a mixture of Pt and base metal ions (Fe 2+, Cr3+) in chloride media. The central focus of the study was directed at comparing selectivity and mass transfer characteristics of Pt ions in a batch reactor and packed-bed column.In a batch reactor, the AC particles were agitated mildly (500 rpm) within the bulk solution (810 mL) while fresh feed was fed (6 mL/min) to the reactor continuously in up flow mode. The ratio of AC mass to solution volume in the stirred batch reactor was kept constant (1 g: 810 mL) at ambient conditions. The mass transfer of Pt ions in the packed-bed column was evaluated by correlating the ratio of Sherwood and Schmidt numbers with Reynolds numbers. In the case of a batch reactor, the rate equation was integrated and then fitted to the adsorption data in order to determine the rate constants and mass transfer coefficients. Separation factors (βPt/Fe, βPt/Cr), in the order of 102 were achieved in a packed-bed column. However, separation factors in a batch reactor were hundred-fold higher than packed-bed column values indicative of superior mass transfer of Pt in an agitated-carbon-in-liquid (ACIL) process.