While effective collision between the dye molecule and elemental iron occurs, elemental iron, as an electron donor, loses electrons and the dye molecule, as an electron acceptor, accepts electrons. Meanwhile, the dye molecule combines with H+ and is transformed into the transitional products. These intermediate products also obtain electrons from elemental iron and combine with H+ again, after which they are transformed into terminal products such as sulfanilic acid and 1-amono-2-naphthol [2,4].