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

Water decontamination remains a challenge in severaldevelopedand developing countries. Affordable and efficient approaches areneeded urgently. In this scenario, heterogeneous photocatalysts appearas one of the most promising alternatives. This justifies the extensiveattention that semiconductors, such as TiO2, have gainedover the last decades. Several studies have evaluated their efficiencyfor environmental applications; however, most of these tests relyon the use of powder materials that have minimal to no applicabilityfor large-scale applications. In this work, we investigated threefibrous TiO2 photocatalysts, TiO2 nanofibers(TNF), TiO2 on glass wool (TGW), and TiO2 inglass fiber filters (TGF). All materials have macroscopic structuresthat can be easily separated from solutions or that can work as fixedbeds under flow conditions. We evaluated and compared their abilityto bleach a surrogate dye molecule, crocin, under batch and flow conditions.Using black light (UVA/visible), our catalysts were able to bleacha minimum of 80% of the dye in batch experiments. Under continuousflow experiments, all catalysts could decrease dye absorption undershorter irradiation times: TGF, TNF, and TGW could, respectively,bleach 15, 18, and 43% of the dye with irradiation times as shortas 35 s. Catalyst comparison was based on the selection of physicaland 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, whichdescribed their applicability in different systems. This comparativeanalysis gives insights into the selection of the right flow-compatiblephotocatalyst for water remediation.

Automated summary

Water decontamination is a challenge in both developed and developing countries, and there is an urgent need for affordable and efficient solutions. Heterogeneous photocatalysts, such as fibrous TiO2, have shown promising potential for water remediation. This study evaluated three fibrous TiO2 photocatalysts and compared their performance in bleaching a dye molecule under batch and flow conditions, providing insights for selecting a suitable flow-compatible photocatalyst for water remediation.