Fibrous TiO₂ Alternatives for Semiconductor-Based Catalysts for Photocatalytic Water Remediation Involving Organic Contaminants

Abstract

Water decontamination remains a challenge in several developed and developing countries. Affordable and efficient approaches are needed urgently. In this scenario, heterogeneous photocatalysts appear as one of the most promising alternatives. This justifies the extensive attention that semiconductors, such as TiO 2 , have gained over the last decades. Several studies have evaluated their efficiency for environmental applications; however, most of these tests rely on the use of powder materials that have minimal to no applicability for large-scale applications. In this work, we investigated three fibrous TiO 2 photocatalysts, TiO 2 nanofibers (TNF), TiO 2 on glass wool (TGW), and TiO 2 in glass fiber filters (TGF). All materials have macroscopic structures that can be easily separated from solutions or that can work as fixed beds under flow conditions. We evaluated and compared their ability to bleach a surrogate dye molecule, crocin, under batch and flow conditions. Using black light (UVA/visible), our catalysts were able to bleach a minimum of 80% of the dye in batch experiments. Under continuous flow experiments, all catalysts could decrease dye absorption under shorter irradiation times: TGF, TNF, and TGW could, respectively, bleach 15, 18, and 43% of the dye with irradiation times as short as 35 s. Catalyst comparison was based on the selection of physical and chemical criteria relevant for application on water remediation. Their relative performance was ranked and applied in a radar plot. The features evaluated here had two distinct groups, chemical performance, which related to the dye degradation, and mechanical properties, which described their applicability in different systems. This comparative analysis gives insights into the selection of the right flow-compatible photocatalyst for water remediation.

Review of the recent advances on the fabrication, modification and application of electrospun TiO2 and ZnO nanofibers for the treatment of organic pollutants in wastewater

“…Briefly, a solution consisting of a polymer, volatile solvent and metal precursor is prepared. Examples of some of the commonly employed metal precursors for the preparation of the TiO 2 nanofibers include titanium (IV) isopropoxide, titanium tetraisopropoxide, titanium (IV) n-butoxide and tetra-n-butyl titanate (da Silva et al, 2023;Li and Xia, 2003;Secundino-Sánchez et al, 2022a;Lv et al, 2021), whereas the ZnO nanofibers are commonly synthesized from salts including zinc acetate and zinc nitrate (Mali et al, 2013;Di Mauro et al, 2016). The preparation of both the ZnO and TiO 2 nanofibers using electrospinning also requires the use of a sacrificial polymer that is chosen based of its thermal degradation (Zagho and Elzatahry, 2016).…”