Photocatalytic degradation of 2,4-dichlorophenol using nanoscale Fe/TiO2

A nano-catalyst Fe on TiO2 was prepared and tested for efficient total organic carbon (TOC) removal during the photocatalytic oxidation of chlorophenols. The preparation included a sol–gel process and calcinations followed by chemical reductive deposition of Fe. The Fe/TiO2 composite catalysts were more effective in dechlorination, oxidation of 2,4-DCP (2,4-dicholorophenol) and TOC removal, under UV irradiation, than pure Fe or pure TiO2. The catalysts were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy. The loaded forms of iron include Fe, Fe2+ and FeOOH due to the reaction with oxygen. The Fe/TiO2 catalyst has significantly increased optical absorption than TiO2. The optimal pH value and iron loading content were determined to be pH 4 and 1 wt% Fe/TiO2, respectively. Degradation/dechlorination and TOC removal after 2 h irradiation with 297 μW/cm2 254 nm UV were 97% and 71%, respectively. The possible reaction mechanisms are discussed.

► The 2,4-DCP (2,4-dicholorophenol) degradation kinetics using Fe or Fe/TiO2 was compared. ► The highest dechlorination and TOC removal rate was obtained using 1 wt% Fe/TiO2 and UV. ► Iron species enhance the degradation via a Schottcky barrier and acting as photo-Fenton reagents. ► Fe/TiO2 can be reused as the cycle from Fe2+ to Fe0 can be maintained by electrons from TiO2 at pH 4–6. ► Cheap metal iron behaves like a noble metal, better than a noble metal in de-chlorination and oxidation of 2,4dichlorophenol.