UV-induction of photolytic and photocatalytic degradation of fumonisins in water: reaction kinetics and toxicity

Although fumonisins are toxic and carcinogenic mold products that contaminate feed, food, and water, their photodegradation has not yet been reported. In this work, the efficiency of photolysis (UV, UV/H2O2, and UV/S2O2−8) and photocatalysis (TiO2 (Degussa P25/Wackherr) and ZnO) for the degradation of fumonisins in an aqueous medium were investigated. In the case of fumonisin B1 (FB1) optimal conditions in terms of pH, the initial concentrations of H2O2/S2O2−8 for UV, UV/H2O2, and UV/S2O2−8 treatments were investigated. The photocatalytic degradation using TiO2 Wackherr as catalyst at natural pH (about 8) proved to be the most efficient treatment for removal of FB1 and FB3. Namely, during the first 30 min of irradiation, 99% of FB1 (1.39 μM) was degraded, while FB3 (0.425 μM) was completely removed during the first 20 min of irradiation. In the case of FB2 (0.687 μM), UV/S2O2−8 was the most efficient treatment, and complete removal occurred in the first 90 min of irradiation. All applied treatments for fumonisins removal have followed pseudo-first-order kinetics under the relevant experimental conditions. Toxicity of fumonisins and their mixtures formed during photodegradation were investigated using mammalian cell lines (BHK, H-4-II-E, Neuro-2a, and MRC-5). The BHK cell line was the most sensitive to fumonisins, especially FB2 and FB3, and its photodegradation mixtures.