Evaluation of the Potentiality of the H₂O₂/IO₄^– Process for the Removal of Acid Orange 10 from the Liquid Phase: Experimental Investigation Coupled with Numerical Analysis Using the Box–Behnken Design

Abstract

This work investigates for the first time the decomposition of Acid Orange 10 (AO10) dye using the H2O2/IO4 – reactive system. The impact on the process efficiency of IO4 – concentration, H2O2 dosage, initial dye concentration, initial pH, temperature, and methanol presence is assessed. The effects of adding different salts and water matrices are examined. The outcomes show that H2O2 and IO4 – concentrations exert a nonmonotonic effect with the maximum AO10 removal percentage, since high levels of both oxidants reduce the presence of reactive radicals and in particular •OH (whose formation is also inhibited by higher temperatures). Under acidic conditions, AO10 degradation is significantly promoted, and the degradation efficiency is higher than 97% for pH ≤5.7, with almost complete removal of the dye achieved at pH of 3. On the other hand, the degradation efficiency is about 16% at neutral conditions and less than 10% for pH of 8 and 10. Moreover, an increase in salinity significantly decreases the effectiveness of AO10 removal, as demonstrated by tests in seawater, natural mineral water, and stream water. The response surface methodology based on the Box–Behnken design is successfully applied to define a functional relationship between the degradation performance of AO10 adopting the H2O2/IO4 – system and operating process parameters.