Photo-Chemical Sucralose Degradation in an Aqueous Medium Using a Photo-Fenton System Equipped with Stainless Steel Mesh Cathodes Modified By Nanostructured TiO 2 - and C|TiO 2 -Based Films for Continuous Electro-Generation of H 2 O 2

Artificial non-caloric sweeteners are non-bioassimilable substances that pass through the human body without biochemical changes. Sucralose, for instance, is 600 times sweeter than natural sucrose, so it is widely used in beverages and processed food products without regulation in many countries. Its environmental persistence of 337 days in sludge allows inferring that these substances can adversely affect the environment in the short or long term, thus classifying sucralose as an emergent pollutant. In this work, stainless steel (SS) mesh working electrodes were modified by TiO 2 - or C|TiO 2 -based nanoparticulate films (where C is carbon Vulcan). Both types of electrodes were employed as cathodes for the electro-generation of hydrogen peroxide (H 2 O 2 ), which was the chemical precursor for photochemical producing •OH radicals able for sucralose degradation in a photo-Fenton system equipped with a 254 nm light source. Preparation of TiO 2 - and C|TiO 2 -based cathodes was performed by electrophoretic deposition method (EPD, 2 V/cm for 40 s) on AISI 304 SS mesh, followed by sintering at 450°C for 1h in the air. The EPD process was performed using aqueous colloidal suspensions containing wt./wt. ratios of C/TiO 2 = 1/100 and 1/10, or TiO 2 without C for comparison purposes. H 2 O 2 electro-generation was carried out via Reaction 1 utilizing a two-electrode cell (3V-cell polarization) containing sucralose dissolved in a pH 2 aqueous sulfates buffer solution perpetually bubbled by air (volumetric flow rate of 17 mL/s) containing gaseous O 2 . In all the cases, a Ti grade 2.0 rod anode was immersed in the electrolyte medium with one of the following cathodes: SS* (polished, degreased, and heated at 450°C for 1h in the air as control electrode), SS||TiO 2 and SS||C|TiO 2 (wt./wt. ratios of C/TiO 2 = 1/100 or 1/10). Furthermore, the cell was illuminated by a 254 nm lamp in order to continuous promotion of the photo-chemical Reaction 2. O 2 + 2H + + 2e - → H 2 O 2 ...(1) H 2 O 2 254mn → 2°OH... (2) Sucralose degradation efficiencies were registered based on the cathodes employed for continuous H 2 O 2 electro-generation. Furthermore, the relative use time was also registered for each cathode. A comparison of these results reveals that when employed SS*, SS||TiO 2 , and SS||C|TiO 2 (wt./wt. ratio of C/TiO 2 =1/100) cathodes the sucralose degradation achieved efficiencies over 90% (i.e. 99.1, 96.8, and 91.3%, respectively). In contrast, SS||C|TiO 2 (wt./wt. rati