ELECTRO-REGENERATION OF Ce(IV) IN REAL SPENT Cr-ETCHING SOLUTIONS: COMPARISON OF SEPARATORS

摘要

Different separators (membranes) were investigated for the electro-regeneration of Ce(IV) from Ce(III) in real spent Cr-etching solutions. The experiments were performed at 2 A and 40°C in a divided cell using real spent Cr-etching solutions as the anolyte and 4 M HNO3 as the catholyte. The anode and cathode materials were platinum (2.25 cm~2) and titanium (1 cm~2), respectively. Among the tested separators (Neosepta CMX, Neosepta AMX, Nation 117, and Nafion 212), the CMX membrane had the best performance in terms of Ce(IV) yield and current efficiency for the electro-regeneration of Ce(IV); the greatest apparent rate constant for Ce(IV) electro-regeneration was 9.4×10~(-5) s~(-1) when using the CMX membrane. The Ce(IV) yield and current efficiency were more influenced by separator thickness than by separator selectivity to anions/cations.