Photocatalytic atrazine degradation by synthetic minerals, atmospheric aerosols, and soil particles

In this work, the photocatalytic atrazine degradation by seven synthetic minerals and five environmental particle samples was examined to investigate a possible contribution of photocatalysis to the abiotic degradation of atrazine in the environment. Particle suspensions containing 500 ng/L atrazine were irradiated with a sun simulator, and the atrazine degradation was monitored by enzyme-linked immunosorbent assay (ELISA): Atrazine detection by ELISA proved to be an useful analytical tool because of low cross-reactivity of atrazine metabolites and high sensitivity with detection limits in the lower nanograms per liter range. The atrazine degradation followed first-order kinetics, and the obtained rate coefficients were compared with the rate of direct photolysis. Known photocatalysts, such as TiO₂ and ZnO, showed the expected fast photocatalytic degradation (k = 27-327 × 10^-3 min^-1) of atrazine. The degradation rates detected upon irradiation of titanium-, zinc-, or iron-containing minerals were orders of magnitudes lower (k = 0,15-0.70 × 10^-3 min^-1) but still significantly faster than direct photolysis without particles (k = 0.10 × 10^-3 min^-1). With environmental particle samples (soot, fly ash, sand, road dust, and volcanic ash), however, no significant photocatalytic activity was observed (k = 0.07-0.16 × 10^-3 min^-1). The atrazine degradation rates were in the range of direct photolysis. Thus photocatalysis by aerosol or soil particles appears not to enhance abiotic atrazine degradation in the environment.