Synthesis and characterization of TiO2 films onto AISI 304 metallic meshes and their application in the decomposition of the endocrine-disrupting alkylphenolic chemicals

This contribution describes the influence of the ratio of polyvinyl alcohol (PVA), TiO2 and wire opening of metal meshes for the construction of a structured catalyst with a uniform coating, that present high adherence and photocatalytic activity. The best coating results were observed for a PVA/TiO2 mass ratio of 0.37 and mesh opening of 546 mu m. This coating exhibited a uniform distribution, high adherence and the maintenance of anatase and rutile phases. These aspects can be related to three variables: (i) the structure of the stainless-steel metal mesh, (ii) the thermal pretreatment and (iii) the amount of organic additive (PVA/TiO2 ratio) employed in the suspensions. The most important achievement of this work was the fabrication of a structured catalyst with excellent stability, without losing activity for the degradation of endocrine-disrupting nonylphenol ethoxylate (NP4EO) in synthetic solution, without poisoning of the catalytic surface. In fact, the results showed that even with a real wastewater matrix, a high photocatalytic activity for NP4EO degradation (91%) was obtained, meaning that this structured catalyst can be applied to solve serious environmental problems as the contamination by endocrine-disrupting NP4EO, without subsequent catalyst recovery and recycle steps.