Kinetics of Oxidation of Iodide (I–) and Hypoiodous Acid (HOI) by Peroxymonosulfate (PMS) and Formation of Iodinated Products in the PMS/I–/NOM System

Abstract

In this work, the kinetics of transformation of iodide (I–) and hypoiodous acid (HOI) by peroxymonosulfate (PMS) and potential formation of worrisome iodinated products in the presence of natural organic matter (NOM) were investigated. As the pH increased from 5 to 10, the apparent second-order rate constants of reaction of PMS with I– gradually decreased from 1.01 × 103 to 3.86 × 102 M–1 s–1, while those for HOI increased dramatically from 1.08 × 102 to 7.90 × 104 M–1 s–1. The obtained pH-dependent rate profiles were explained well by the effects of pH-affected speciation of PMS and/or HOI. Considerable amounts of total organic iodine (TOI) could be formed in the PMS/I–/NOM system over a wide pH range. Under similar conditions, the TOI levels formed in the PMS/I–/NOM system were generally higher than those formed in the case of HOCl but much lower than those formed in the case of NH2Cl. Also, specific iodoform (IF) and monoiodoacetic acid (MIAA) were detected in both simulated and authentic waters during...