Solar photocatalytic removal of tetracycline using bismuth oxyiodide: Intermediates identification, toxicity assessment and effect of solution matrix

• A BiOI photocatalyst is successfully prepared. • BiOI is an efficient photocatalyst for mineralizing TC. • Final intermediates of TC degradation have lower toxicity than TC molecules. • TC molecules are completely removed from spiked real samples. Tetracycline, the second most common antibiotic in production and usage, was degraded using BiOI photocatalyst which was synthesized by solvothermal method. The toxicity of TC degradation products was assessed by photoluminescence inhibition rate using Vibrio fischeri and the application of the treatment process was tested on spiked real samples. In direct photolysis, only 20 % of TC was removed, while, the maximum removal of 100 % was obtained in the photocatalysis process after 120 min of illumination. The inhibition rate for TC concentrations including 1, 2, 3, 4, and 5 mg L −1 was found to be 62, 64, 75, 78, and 85 %, respectively. The toxicity of the TC solution reached the maximum after 30 min irradiation and then gradually decreased to <30 % after 120 min of radiation. any intensity peak was found in MS spectra, showing that TC molecules were completely removed. The results show that photocatalysis using BiOI can be a promising candidate for removing TC from natural water despite the presence of organic matter and dissolved solids.