Classic Fenton produces Fe(lll) and hydroxyl radicals.
The fenton-type reaction with a source of Fe(ll) and HONO2 forms Fe(lll), nitrite and hydroxyl radicals followed by nitrogen oxides.
So the observation that the products of these two reactions interacting with Na2S differently could suggest something other than just an hydroxyl
radical exposure.
----------------------------------------------
Came across paper that may be relevant. See Equation (1) at https://www.academia.edu/1557498/Addition_and_Redox_Reactivi... with the formation of the ion Fe(CN)5N(O)SH]3- . Note, per prior discussion,
HS• reacts with NO• to generate thionitrous acid (HSNO).