Photocatalytic ozonation of parabens mixture using 10% N-TiO 2 and the effect of water matrix.

Nitrogen-doped TiO ₂ was applied in photocatalytic ozonation reactions for the degradation of a mixture of five parabens under UVA radiation, being evaluated the influence of the reaction medium. The initial mixture parabens concentration considered in these experiments was 50 mg L ^-1 . The parabens degradation rate was considerably enhanced under neutral pH, specially using a buffered solution, leading to a complete removal under 60 min and with transferred ozone dose (TOD) 36% lower compared to reaction under natural conditions. Isopropanol, known radical scavenger, impeded the complete contaminants removal, affecting the reaction route and by-products formation, but when KI was jointly added, total removal was achieved under 30 min and with a TOD of 25.9 mg L ^-1 . Parabens depletion was also improved in the presence of Cl ^- , SO ₄ ^2- and HCO ₃ ^- , commonly present in wastewaters. The use of river water (RW) and a secondary wastewater (SWW) as water matrices maintained the process efficiency with lower TOD required, and treated solutions presented lower phytotoxicity towards Lepidium sativum.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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