The role of multiwalled carbon nanotubes (MWCNTs) in the catalytic ozonation of atrazine

•A new reaction pathway for conversion of atrazine in catalytic ozonation is proposed.•A lower toxicity effluent is obtained compared to non-catalytic route.•A significant degree of atrazine mineralisation was achieved. Multiwalled carbon nanotubes (MWCNTs) are used as catalysts in ozonation of atrazine in aqueous solutions. The catalyst changed the distribution of atrazine degradation intermediates, leading to the decrease in the effluent toxicity compared to non-catalytic ozonation and an increase in the overall mineralisation of atrazine. However, the overall rate of atrazine conversion was somewhat reduced in the presence of the nanotube catalyst (apparent rate constant: 0.233min−1versus 0.143min−1 in the presence of the nanotubes). Detailed analysis of intermediates in catalysed and non-catalysed reactions allowed to propose the likely reaction pathway in the presence of the nanotubes.