optimization and modeling of microcystin-lr degradation by tio_2 photocatalyst using response surface methodology

Introduction: microcystinleucine arginine (mclr) is a toxin with harmful effects on the liver, kidney, heart, and gastrointestinal tract. so, effective removal of mclr from water resources is of great importance. the aim of this study was to remove microcystinlr (mclr) from aqueous solution by titanium dioxide (tio2).materials and methods: in the present study, tio2, as a semiconductor, was used for photodegradation of mclr under ultraviolet light (uv). the response surface methodology was applied to investigate the effects of operating variables such as ph (a), contact time (b), and catalyst dose (b) on the removal of mclr. the mclr concentration was measured by highperformance liquid chromatography (hplc).results: the results showed that single variables such as a, b, and c had significant effects on mclr removal (pvalue < 0.05). in other words, increase of the contact time and catalyst dose had a positive effect on enhancing the removal efficiency of mclr, but the effect of ph was negative. the analysis of variance showed that bc, a^2, and c^2 variables had a significant effect on the mclr removal (pvalue < 0.05). finally, the maximum removal efficiency of mclr was 95.1%, which occurred at ph = 5, contact time = 30 minutes, and catalyst dose = 1 g/l.conclusion: according to the findings, tio_2, as a photocatalyst, had an appropriate effect on degradation of the mclr.