The multiple role of inorganic and organic additives in the degradation of reactive green 12 by UV/chlorine advanced oxidation process

Removal of persistent textile dyes from wastewater by Fe(ii)/H2O2/H3NOH+ integrated system: process performance and limitations

“…This is due to the strong quenching of hydroxyl radicals by NO 2 − according to reaction (28), where the resulting is a less powerful oxidant than ˙OH. 44 …”

“…Br − is an efficient ˙OH-scavenger according to reactions (29)–(32). 44,57 The contribution of the resulting bromide-containing radicals is not significant compared to that of ˙OH, by reason of the highly reactive character of the latter. 57 Br − + ˙OH ⇌ BrOH˙ − , k 29 = 1.1 × 10 10 M −1 s −1 , k −29 = 3.3 × 10 7 M −1 s −1 BrOH˙ − → Br˙ + OH − , k 30 = 1.9 × 10 8 M −1 s −1 BrOH˙ − + Br − → Br˙ + OH − , k 31 = 4.4 × 10 10 M −1 s −1 Br˙ + Br − ⇌ Br 2 ˙ − , k 32 = 1.2 × 10 10 M −1 s −1 , k −32 = 10 5 M −1 s −1 …”

“…EPR and chemical probe techniques are usually employed for determining the reactive species involved in AOPs, 3,38,39,[42][43][44] and both of these techniques provided similar results and conclusions. 42,43 Because of the simplicity of the second one (the chemical probe), it has been adopted in the present study.…”

“…The rate constant of the cOH-NOM reaction is 2.5 Â 10 4 M À1 s À1 . 44 This relatively low rate constant justies the insignicant reduction imposed by NOM at 10 mg L À1 compared to 1 mg L À1 (lower reactivity toward cOH) for the ternary system Fe(II)/H 2 O 2 /H 3 NOH + , as shown in Fig. 10.…”

“…Br À is an efficient cOH-scavenger according to reactions ( 29)- (32). 44,57 The contribution of the resulting bromidecontaining radicals is not signicant compared to that of cOH, by reason of the highly reactive character of the latter. 57 Br À + cOH # BrOHc À , k 29 ¼ 1.1 Â 10 10 M À1 s À1 , k À29 ¼ 3.3 Â 10 7 M À1 s À1…”