While activated sludge treatment is currently the preferred process for the removal of tributyl phosphate (TBP) at the mg.L-1 level, it is well known that this recalcitrant molecule is incompletely degraded, stimulating research into alternative approaches, such as advanced oxidation. The aim of this study was to characterize the degradation mechanism of TBP during ultraviolet/H2O2 treatment using 31P NMR, ionic chromatography and total organic carbon analysis. The effects of initial pH, amount of oxidant and pollutant concentration were also assessed using an experimental design approach. The results of this parametric study show that ultraviolet/H2O2 photo-oxidation efficiently degrades TBP at concentrations up to 600 mg.L-1, with >90% phosphate release and up to 95% removal of total organic carbon within 1 h. The data also show that the main reaction intermediates are short carboxylic acids, resulting from the released alkyl groups, meaning that an interesting application of this process may be to rapidly pre-treat industrial effluent upstream of activated sludge reactors.
Keywords: AOP; Water treatment; degradation mechanism; organophosphates; photo-oxidation.