Roles of free radicals in NO oxidation by Fenton system and the enhancement on NO oxidation and H₂O₂ utilization...

Low H₂O₂ utilization efficiency is the main problem when Fenton system was used to oxidize NO in flue gas. To understand the behaviour of the free radicals during NO oxidation process in Fenton system is crucial to solving this problem. The oxidation capacity of [Formula: see text] and [Formula: see text] on NO in Fenton system was compared and the useless consumption path of [Formula: see text] and [Formula: see text] that caused the low utilization efficiency of H₂O₂ were studied. A method to enhance the oxidation ability and H₂O₂ utilization efficiency by adding reducing additives in Fenton system was proposed. The results showed that both of [Formula: see text] and [Formula: see text] were active substances that oxidize NO. However, the oxidation ability of [Formula: see text] radicals was stronger. The vast majority of [Formula: see text] and [Formula: see text] was consumed by rapid reaction [Formula: see text] , which was the primary reason for the low utilization efficiency of H₂O₂ in Fenton system. Hydroxylamine hydrochloride and ascorbic acid could accelerate the conversion of Fe³⁺ to Fe²⁺, thereby increase the generation rate of ·OH and decrease the generation rate of [Formula: see text]. As a result, the oxidation ability and H₂O₂ utilization efficiency were enhanced.