Substituent effects on photodegradation of phenols in binary mixtures by hybrid H2O2 and TiO2 suspensions under UV irradiation

The HPLC graphs for reactants and intermediates after 3-h degradation of binary mixtures of phenol/o-cresol (upper) and phenol/4-CP (lower) at pH 7.5 and 25 °C by H2O2/TiO2/UV (2.0 mM H2O2, 1 g/L TiO2, 100-W UV). All intermediates have a shorter retention time compared to the parent phenols. Additional intermediates are observed due to the presence of the second reactant. The existence of these intermediates is also considered to cause the solutions with different colors.100