Kinetics and mechanism of photochemical reactions of peroxomonosulfate in the presence and absence of 2‐propanol

The photochemical decomposition of peroxomonosulfate (PMS) in the presence and absence of 2‐propanol at 25°C was found to obey an overall first‐order rate – d [PMS]/ dt = k ϕ [PMS]. In the absence of 2‐propanol, the quantum yield ≤ for the decomposition of PMS was found to depend upon the concentration of PMS at [PMS] > 2 × 10 − M , and is independent of concentration at [PMS] > 2 × 10 −2 M . The quantum yield in the presence of 2‐propanol was found to be 3.03 at [PMS] = 1 × 10 −2 M and 4.45 at higher concentrations of PMS. In the pH range of 2–9.0 the quantum yield was found to be independent of pH, and the overall rate constant k ϕ was found to be 6.49 × 10 −3 s −1 and 1.68 × 10 −3 s −1 , respectively, in the presence and absence of isopropanol. A suitable chain mechanism is proposed and explained.