Extraction of platinum at high phase ratio via a rotating packed bed integrated with falling film

Abstract

The recovery of platinum is an urgent requirement because of its limited resources and wide application in catalysis, electrochemistry, and so forth. Liquid-liquid extraction is an efficient process in metal recovery due to high product selectivity and purity. However, the extraction of platinum was challenging at a high aqueous-to-organic phase ratio (R), restricted by insufficient contact between phases. This work developed a rotating packed bed integrated with falling film (FF-RPB) to intensify the platinum extraction process. The organic phase consisting of TOA, TBP, and kerosene was broken into droplets by rotating packing. The aqueous phase, the Pt(IV) acidic chloride solution, flowed downward as liquid film on the FF-RPB’s inner wall. The organic micro droplets impacted on the aqueous film, and the extraction was gradually completed during the coflowing process. Results indicated that the extraction efficiency was improved with the increment of rotational speed and TOA concentration and reduced with the enlargement of pH value, Pt(IV) concentration and aqueous-to-organic phase ratio. The extraction efficiency and enrichment factor reached 0.993 and 14.9 at R = 15 and aqueous phase flowrate of 300 L·h−1, respectively. Compared with batch apparatus and microreactors, the FF-RPB showed great advantages, which realized prominent extraction of platinum at a higher aqueous-to-organic phase ratio and a larger throughput.