“…[40] In addition, H 2 O 2 can decompose into H 2 O, which in turn interacts with the regions with deficit of electron density, forming an •OH and a proton (H + ), while the molecular oxygen (O 2 ) can interact with the accumulation of electron density, generating a superoxide radical (•O 2 À ) and evolving into an oxygen singlet ( 1 O 2 ), or with an H + , forming a hydroperoxyl radical (•O 2 H). [41] To investigate the oxidation mechanism, specific scavengers were used for the 1 O 2 (ascorbic acid, AA), •O 2 H (p-benzoquinone, BQ) and •OH (potassium acid biphthalate, KABP) species, as well as for the electron density deficit, i. e., holes, h + (ammonium oxalate, AO), and the electron density accumulation, i. e., e À (silver nitrate, SN) (Figure 4A). [42] A significant reduction in the conversion rate was not observed when scavengers of the 1 O 2 and •O 2 H species were used, evidencing that these species were not involved in the sulfide oxidation mechanism.…”