Boron doped TiO2 catalysts for photocatalytic ozonation of aqueous mixtures of common pesticides: Diuron, o-phenylphenol, MCPA and terbuthylazine

Photocatalysts were characterized by ICP-EOS, N2 adsorption-desorption, XRD, XPS, and DR-UV-Vis spectroscopy. Four recalcitrant herbicides and pesticides (diuron, o-phenylphenol, 2-methyl-4-chlorophenoxyacetic acid (MCPA) and terbuthylazine) were subjected to degradation by ozonation, photolytic ozonation, photocatalysis and photocatalytic ozonation using the prepared catalysts under simulated solar irradiation in a laboratory scale system. The boron that was not incorporated to the TiO2 interstitial positions was unstable and leached to the solution. The washed B-doped TiO2 catalysts, with 0.5-0.8 wt.% of interstitial boron were more active than bare TiO2 for the removal and mineralization of the target compounds. The combination of ozonation and photocatalysis led to faster mineralization rates and allowed the complete removal of the pesticides below the regulatory standards. The B-doped catalyst was stable and maintained 75% mineralization after 3 consecutive runs.