Search

The transformation of iodide (I-) and hypoiodous acid (IO-) by Fe (II)-activated peroxydisulfate (PDS) in the presence of natural organic matter (NOM) was investigated. In the water of a reservoir in Shenzhen, four kinds of organic matter were detected: iodoform>diiodo-bromomethane> dibromo-iodomethane>dichloromethane. As pH increased from 3 to 10, I- conversion rate decreased from 31.0% to 11.0%. There is basically no iodic acid (IO-3 ) generated under alkaline conditions, probably due to these organic matters. When PDS concentration is low, PDS can oxidize part of I- to IO-, and the oxidation of I- into IO-3 reaction and continued oxidation reaction exist at the same time, so some IO-3 is generated in the system. As the proportion of Fe (II) increases, the generation rate of IO-3 gradually increases. When Fe²þ/PDS is 1:5, 2:5, and 3:5, the conversion rates of IO-3 are 4.7%, 6.5%, and 8.4%, respectively. There are two main reasons for this: (i) the reaction of IO- produced in the system with humic acid (HA) inhibits the further conversion of IO- to IO-3 ; (ii) both HA and I- in the system can react with PDS, resulting in a reduction in the oxidation rate of I-. [ABSTRACT FROM AUTHOR]