Photocatalytic removal of phenol using titanium dioxide deposited on different substrates: Effect of inorganic oxidants

• pH plays a role in by-products formation.
• The addition of electron acceptors such as hydrogen peroxide and persulfate has not increased the catalytic activity under the experimental conditions of this study.
• Comparison of different catalysts tested shows that the TiO2 deposit on glass is the most stable and provides the best mineralization.
• Mineralization is better when Ahlstrom paper is reused.

Photocatalytic degradation of phenol has been investigated using a laboratory reactor and UV-A lamp (BLB) and different commercial catalysts: TiO2PC500 fixed on cellulose paper (Ahlstrom paper) and TiO2 (Degussa P25) on stainless steel or conducting glass. Thin layers of TiO2 on glass and stainless steel were prepared by electrophoretic deposition. Phenol and by-products were monitored by HPLC system equipped with a phenyl column and PDA detector. The effects of various operating parameters such as initial concentration of phenol (100–500 μmol L−1), initial pH (2.0–10.0) and addition of inorganic oxidants (H2O2, S2O82−) were evaluated on Ahlstrom paper. The results revealed that the best conditions of phenol removal were 100 μmol L−1 of initial concentration, natural pH (5.0–6.0) and absence of inorganic oxidants when using Ahlstrom paper. Also, analysis of the by-products shows their dependence on initial pH. The comparison of phenol removal efficiency shows that thin layers of TiO2 P25, deposited on glass, present the best photocatalytic activity. Several experiments performed with the same photocatalyst show that washing layers with pure water several times and drying at low temperature allow reactivation of the catalysts.