The impact of environmental water on the potential application of core-shell titania-silica nanospheres as photocatalysts

Krzysztof Cendrowski; Kamila Pachnowska; Adrian Augustyniak; Jagoda Wierzbicka; Filip Pratnicki; Pawel Kucharski; Wojciech Kukułka; Ewa Mijowska

doi:10.1088/1361-6528/abf9c5

The impact of environmental water on the potential application of core-shell titania-silica nanospheres as photocatalysts

Nanotechnology. 2021 May 10;32(31). doi: 10.1088/1361-6528/abf9c5.

Authors

Krzysztof Cendrowski^{1

2}, Kamila Pachnowska^{1

3}, Adrian Augustyniak^{4

5}, Jagoda Wierzbicka¹, Filip Pratnicki^{1

6}, Pawel Kucharski¹, Wojciech Kukułka¹, Ewa Mijowska¹

Affiliations

¹ Department of Nanomaterials Physicochemistry, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Szczecin, Al. Piastów 45, Szczecin 70-311, Poland.
² Faculty of Civil and Environmental Engineering, West Pomeranian University of Technology, Szczecin, Al Piastów 50a, Szczecin 70-311, Poland.
³ Department of Horticulture, Faculty of Environmental Management and Agriculture, West Pomeranian University of Technology, Szczecin, Juliusza Słowackiego 17, Szczecin 71-434, Poland.
⁴ Department of Chemical and Process Engineering, Faculty of Chemical Technology and Engineering, West Pomeranian University of Technology, Szczecin, Al. Piastów 42, 71-065 Szczecin, Poland.
⁵ Building Materials and Construction Chemistry, Technische Universität Berlin, Gustav-Meyer-Allee 25, D-13-355 Berlin, Germany.
⁶ Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland.

PMID: 33878741
DOI: 10.1088/1361-6528/abf9c5

Abstract

In this study, the core-shell silica nanospheres modified with titanium dioxide were tested in the photocatalytic decomposition of dyes. The presented data underlines the advantages and shortcomings in the potential application of silica-based catalysts to neutralize organic pollutants. During the photocatalytic reaction in distilled water, catalysts showed decreased efficiency due to a carbon layer deposited on its surface. This finding set an additional goal to investigate the possibility of regenerating the photocatalyst. Studies have shown that the catalyst could be successfully reused following the thermal removal of deposited carbon.Furthermore, the reactivated silica-titania catalysts exhibited comparable photocatalytic performance to the newly made nanomaterial. Surprisingly, catalyst application in the river water eventually resulted in the permanent deactivation of silica-titania nanospheres, which was caused by the interchangeable silica dissolution/precipitation process on the surface of the studied nanomaterial. In environmental water, silica dissolves and precipitates on titanium dioxide's surface, blocking the interaction between organic compounds and TiO₂. The deactivation occurring in the environmental samples is irreversible. In distilled water, the decomposition of organic compounds leads to photocatalysts' deactivation by forming a carbon layer on their surface. Reactivation of the silica-based photocatalyst after distilled water is achievable by annealing at a high temperature. In light of our findings, the combination of the photocatalytic properties of TiO₂and the silica template shows no prospects in the purification of polluted waste or environmental water.

Keywords: catalysts; photocatalysis; river water; silica dissolution; silicates.