Enhanced photocatalytic reduction of trichloroacetic acid using F-TiO2 in the presence of methanol: degradation kinetics and byproducts pathway

Trichloroacetic acid (TCAA) is considered as one of the major of water chlorination by-products. The present work demonstrates decomposition, mineralisation and dechlorination of TCAA by photocatalytic reduction using F doped TiO₂. In this regard, the effects of various operational factors including F-TiO₂ dose, the initial concentration of TCAA, photo-reaction time and solution pH were examined on the process efficiency. Based on the results, $HC{O}_3^{-}$,$P{O}_4^{-3}$,$S{O}_4^{-2}$,$Cl-$and$C{O}_3^{-2}$, as the common anions in water, had no considerable impact on the TCAA degradation efficiency. Decomposition and mineralisation rate of TCAA by MeOH/UV/F-TiO₂process under the optimum conditions (catalyst dosage of 0.34 g L⁻¹, the contact time of 76 min, TCAA content of 1 mg L⁻¹ and pH of 7.9) were found to be 97.1% and 68%, respectively. The decomposition intermediates of TCAAdetected by LC/MS and LC-MS/MStechniques were non-chlorinated compounds, mainly formic and acetic acids. It can be concluded thatMeOH/UV/F-TiO₂processcan use as low energy and efficiently treatment method for the degradation of TCAA contaminated water and wastewater.