Removal of Safranin O from Water by UV/TiO2/IO3- Advanced Oxidation Process: Parametric Study and Impact of Inorganic Ions and Humic Acid

In the present paper, the influence of iodate (IO3-) ions on the photocatalytic process using titanium dioxide (UV/TiO2) was systematically examined. The innovative studied system (UV/TiO2/IO3-) demonstrated high performance in the elimination of safranin O (SO), a model dye, from water due to the implication of iodine radicals (IO3 center dot, IO2 center dot, IO center dot, etc.). The degradation was assessed by monitoring the change in initial substrate concentration (5-30 mg center dot L-1), TiO2 loading (0.01-3 g center dot L-1), IO3- concentration, liquid temperature, and initial pH. Further enhancement of oxyanion amount was beneficial for the initial rate of degradation (r(0)) over the range 0.1-50 mM, such that r(0) rose from 0.724 to 1.12 mg center dot L-1 center dot min(-1). However, a concentration of 100 mM IO3- slowed the removal kinetics. Low pH values were found to be favorable for pollutant removal. Furthermore, a variety of inorganic and organic substances was employed to clarify the effect of the UV/TiO2/IO3- process in natural waters. The findings revealed a negative impact of chloride excess in seawater and a decline in SO degradation in mineral water as a result of HCO3- presence at more than 1 mM. At high concentrations of natural organic matter, the heterogeneity and the strong adsorption of humic acid on the TiO2 surface were found to be harmful for SO decay.

Automated summary

The influence of iodate ions on the photocatalytic process using titanium dioxide was explored in this study. The system UV/TiO2/IO3- showed excellent performance in removing safranin O from water due to the involvement of iodine radicals. Factors such as substrate concentration, TiO2 loading, IO3- concentration, liquid temperature, and initial pH were found to affect the degradation process. The presence of chloride in seawater and high concentrations of natural organic matter were found to hinder the degradation process.