Rapid catalytic degradation of refractory textile dyes in Fe(II)/chlorine system at near neutral pH: Radical mechanism involving chlorine radical anion (Cl2[rad]−)-mediated transformation pathways and impact of environmental matrices

Abstract

Owing to the marked stability and resistance to biodegradation of synthetic dyes, their removal from industrial wastewater is a very difficult process. Herein, we investigated the feasibility of Fe(II)/chlorine system to remove synthetic dyes from water. It was found that the presence of chlorine in solution containing 25 µM of Fe(II) at pH 5 accelerated the removal of dyes by more than 60% within 30 s of treatment. Radical scavengers studies using nitrobenzene, benzoic acid, t-butanol and sodium azide as specific probes revealed that Cl2[rad]− plays the dominant role in the oxidative process involving Fe(II)/chlorine system, although other reactive radicals such as [rad]OH, Cl[rad] and ClO[..