Investigation into the efficiency of photocatalytic oxidation of aqueous solutions of organic toxins in a unit with an automatically cleaning bismuth-silicate photocatalyst

Abstract

This investigation reveals the possibility of effective photocatalytic purification of aqueous solutions of organic pollutants in an experimental unit with an automatically cleaned photocatalytic coating. The automatic cleaning process is realizing by friction of rotating cylindrical photocatalytic coating carriers against a replaceable brush module. Based on data on phase analysis and sorption activity, an optimal silicate carrier was selected for further formation of a continuous coating with high photocatalytic activity on its surface. The effect of its multiple applications (1–4) and temperature (500 °C and 700 °C) on the formation, phase composition, morphology and photocatalytic properties of the coating was studied. It is shown that the highest photocatalytic activity of the coating is achieved with a double application and annealing temperature of 500 °C. Phase analysis and electron microscopy data indicate that with the above synthesis parameters, a continuous coating consisting of a strontium bismuthate phase in strontium to bismuth ratio close to 1:5 is formed. In an experimental wastewater purification unit equipped with samples of the coating that had the highest photocatalytic activity, the efficiency of photo-oxidation of real organic pollutants of wastewater was assessed by bio-testing with Lemna minor as a biological object. Comparative assessment of the efficiency of toxic impact reduction was carried out for two types of organic pollutants: (1) single-stage oxidizing; (2) having photo-oxidation intermediates. For both types of organic pollutants, the effectiveness of the photocatalytic material in reducing the toxic impact on the biological site has been demonstrated.