Photodegradation of 1-hexyl-3-methylimidazolium by UV/H2O2 and UV/TiO2: Influence of pH and chloride

The degradation of imidazolium salt by advanced oxidation processes has been demonstrated in the literature, but do not report on the efficacy of pH and chloride. In the present work, a comparative study of the influence of pH (in the range of 1-12), and chloride (in the range of 0-0.1 mol L−1), at natural and acidic pH, has been investigated in UV254/H2O2 and UV300 < λ < 800/TiO2 processes in aqueous solution for the degradation of an ionic liquid: hexyl methyl imidazolium chloride (HMImCl). It was found that the effect of the pH on the degradation rate is not only dependent on the TiO2 surface charge, but also on the formation of free hydroxyl radicals. In the case of UV254/H2O2 process, there was a slight decrease with the increase in pH value. This study has been demonstrated no effect of chloride concentrations on the degradation of HMImCl in UV254/H2O2 at natural pH. However, in UV300 < λ < 800/TiO2 process chloride at high concentration hindered the degradation. Photodegradation of HMImCl was strongly affected by the chloride concentrations in acidic aqueous solution in the both processes.