Photocatalytic degradation of commercial methyl parathion in aqueous suspension containing La‐doped TiO2 nanoparticles

The photocatalytic degradation of a commercial methyl parathion (MP) under UV irradiation was investigated in aqueous suspension containing lanthanum‐doped mesoporous TiO2 nanoparticles (La/m‐TiO2) as photocatalyst. The rate of photodecomposition of MP was measured using UV‐Vis spectrophotometry, and its mineralization was followed using ion chromatography (IC). The identification of possible intermediate products was carried out using several powerful analytical techniques such as gas chromatography–pulsed flame photometric detector (GC–PFPD) and high performance liquid chromatography–mass spectroscopy (HPLC–MS). Under our conditions, complete disappearance of 20 mg/L of MP occurred within 2 h of illumination, whereas complete mineralization of MP was not achieved through IC analysis. There was a single intermediate product found in the research, which was identified to be methyl paraoxon, owing to the substitution of S by the O atom in the MP molecule. Based on the experimental facts, it is concluded that MP was mainly attacked not by OH radicals but photo‐generated holes (h+), resulting from the good adsorption of MP on the catalyst surfaces due to the enhanced adsorption by La doping.