Sorption of U(VI) on the 4-Mercaptopyridine Self-Assembled Monolayer

Abstract

The sorption of U(VI) on the 4-mercaptopyridine self-assembled monolayer (4-PyS-SAM) on Au(111) was studied by cyclic voltammetry. Cyclic voltammograms (CVs) of the 4-PyS-SAM working electrode were obtained by contact with 1mM UO2(NO3)2 solution, 1mM UO2(NO3)2 and 50mM acetic acid solution, or 1mM UO2(NO3)2 and 50mM oxalic acid solution for 6 h at pH 4. The reduction current of U(VI) to U(V) was detected in the CV. The CV of the U(VI) associated 4-PyS-SAM after transport to U(VI)-free 0.1M NaClO4 solution showed that the reduction current was detected in the cases of UO2(NO3)2 and U(VI)-acetate, but not in the case of U(VI)-oxalate solution, indicating that U(VI) was adsorbed on the 4-PyS-SAM from the UO2(NO3)2 and U(VI)-acetate solutions, but not from U(VI)-oxalate solution. These results suggest that stability of U(VI)-4-PyS-SAM is not so high that U(VI)-4-PyS-SAM cannot be formed in the presence of 50mM oxalate.