“…Whereas inorganic acids, alkalis, salt reagents and their combinations have been widely investigated as leaching agents Parhi et al, 2013;Park et al, 2012;Ramirez et al, 2013), only a few studies (Mulak et al, 2006;Szymczycha-Madeja, 2011) have investigated the effects of oxalic acid (H 2 C 2 O 4 ) combined with H 2 O 2 on the leaching of Mo and Ni from spent catalysts. In Szymczycha-Madeja's work, the leaching kinetics of Mo, Ni, V and Al from a spent hydrodesulfurization catalyst in a solution containing H 2 C 2 O 4 and H 2 O 2 was investigated, but according to the experimental results, the leaching efficiencies of the metals were not high.…”