Structuring efficient photocatalysts into bespoke fiber shaped systems for applied water treatment

• Published in: Chemosphere (Oxford) 2021-08, Vol.277, p.130253-130253, Article 130253
• Main Authors: Theodorakopoulos, George V., Romanos, George Em, Katsaros, Fotios K., Papageorgiou, Sergios K., Kontos, Athanassios G., Spyrou, Konstantinos, Beazi-Katsioti, Margarita, Falaras, Polycarpos
• Format: Article
• Language: English
• Subjects: Alginate; Batch reactor; MO degradation; Photocatalytic hollow fibers; Titania; Water treatment
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2021.130253

In this study, structured photocatalytic systems were successfully developed by a facile method based on Alginate molds and a wet-spinning/cross-linking technique, yielding commercial photocatalyst (Degussa P25) in the form of all-ceramic hollow fibers (HFs). Taking advantage of alginate’s exceptional sorption properties, copper augmented HFs were also developed. The structured photocatalysts were thoroughly characterised by a variety of techniques, including nitrogen adsorption, SEM/EDS, XRD, XPS and Raman. Synthesis and heat treatment parameters were found to affect the fibers’ properties, allowing their optimization. Treatment at 600 °C under Ar was found to produce the best performing photocatalysts in terms mechanical stability, resistance to attrition and photocatalytic performance. Ca-Alginate precursors led to structures with increased mechanical stability, while Cu-Alginate decorated the surface of the photocatalyst with highly dispersed copper nanoparticles, in the state of metallic and CuO. The developed materials were photo-catalytically active, while the copper decorated ceramic HFs exhibited the highest MO adsorption and photocatalytic degradation performance, reaching a MO removal of 73.4%. The synergestic effect of adsorption on the MO degradation performance was also noticed. Moreover, the copper addition facilitated the photocatalytic process by improving the electron-hole separation and inhibiting the recombination effects. The presence of carbon residue was also beneficial, enhancing the MO sorption on the photocatalysts. It is noteworthy that the structured photocatalysts retained their efficiency for at least four photocatalytic cycles. The prepared ceramic HFs exhibited enhanced mechanical properties and excellent resistance to attrition after subsequent cycles, rendering them excellent candidates for application in industrial wastewater processes. [Display omitted] •Residual carbon enhances the mechanical properties of TiO2 hollow fibers (HFs).•Chelating properties of biopolymer result to well dispersed copper nanoparticles.•Copper and residual carbon enhance HFs’ adsorptivity and photocatalytic efficiency.•Copper-decorated HFs exhibited higher performance than the prototype photocatalyst.