Invited paperEfect of TiF surface interaction on the photocatalytic degradation of phenol, aniline and formic acid

- Fluoride interaction generates surface electron traps in TiO2 identified by FTIR.
- The formation of (OHsurf) was significantly enhanced in F-P25 and F-SA.
- Similar increases of kphenol in F-P25 and F-SA respect to P25 and SA was observed.
- Electrostatic fields generated increasing the degration constants of F-P25 and F-SA.

A study is undertaken of the effect of fluorinating two TiO2 catalysts, both with the same surface area but one composed only of pure anatase phase (SA) and the other of mixed anatase and rutile phases (P25), on the degradation of phenol, formic acid and aniline. The catalysts were characterised by FTIR, BET, EDAXs, SEM, XRD and DRS-UV-vis studies. The method used for synthesis of the F-P25 and F-SA resulted in fluorinated catalysts with properties different to those of other fluorinated catalysts reported in the bibliography. The results obtained show that, unlike other studies in which the formation of free hydroxyl radicals (OHfree) was enhanced with the fluorinated catalysts, in the F-P25 and F-SA catalysts it was the formation of surface hydroxyl radicals (OHsurf) which was significantly enhanced. In this way, the F-P25 and F-SA catalysts gave rise to higher degradation rate constants of phenol (kphenol), aniline (kaniline) and formic acid (kformic) than the P25 and SA catalysts.

Apparent first order kinetic constants for aniline, phenol and formic acid photocatalytic oxidation in presence of the different catalysts.Phenol-1: kphenol in study with phenol 0.51 mM; Phenol-2: kphenol in study with mixtures phenol:muconic acid (0.51 mM: 0.51 mM); Phenol-3: kphenol in study with mixtures phenol:muconic acid (0.25 mM: 0.25 mM).Muconic-1: kmuconicacid in study with muconic acid 0.51 mM; Muconic-2 kmuconicacid in study with mixtures phenol:muconic acid (0.51 mM: 0.51 mM); Muconic-3: kmuconicacid in study with mixtures phenol:muconic acid (0.25 mM: 0.25 mM); Muconic-4: kmuconicacid in muconic acid photolysis.142