Development of an integrated flow injection system for the electro-oxidative leaching of uranium from geological samples and its spectrophotometric determination with Arsenazo III.
This work proposes a new procedure for on-line electro-oxidative leaching and spectrophotometric determination of uranium in ore samples. By associating a conventional flow injection system, used for uranium determination with Arsenazo III, with an on-line system for electro-oxidative leaching, a fully integrated system was assembled. The systems were integrated after achieving optimum conditions for uranium determination and leaching. According to the results obtained in the present work, a current density of 280 mA cm(-2) generated enough hypochlorite ions in the electrolyte solution (3.6 mol L(-1) HCl+2% (w/v) NaCl) to promote quantitative oxidation of U(IV) to U(VI) thus improving the extraction efficiency. The slurry density did not significantly affect the performance of the system and the increasing temperature resulted in a decrease in extraction efficiency. This methodology was applied in the determination of U(3)O(8) in four ore samples and the results obtained agreed with those obtained by ICP-MS after conventional wet acid digestion of the samples.
de Sousa
Alvaro Serafim F
AS
Departamento de Química Analítica, Universidade Federal Fluminense, Niterói, RJ 24020-141, Brazil.
Ferreira
Elizabeth M M
EM
Cassella
Ricardo J
RJ
D001150:Arsenazo III / Q000032:analysis*; D004583:Electrons; D017022:Flow Injection Analysis / Q000295:instrumentation* / Q000379:methods*; D019015:Geologic Sediments / Q000737:chemistry*; D009862:Online Systems; D010084:Oxidation-Reduction; D013053:Spectrophotometry; D014501:Uranium / Q000032:analysis* / Q000302:isolation & purification*
D001150:Arsenazo III; D014501:Uranium