Application of birnessite-type solids prepared by sol–gel and oxidation methods in photocatalytic degradation of 4-nitrophenol

ABSTRACT

Potassium birnessites were prepared using two methods, sol–gel or oxidation. The solids were characterised by element chemical analysis, powder X-ray diffraction, FT-IR spectroscopy, thermal analyses, and nitrogen adsorption. The evolution of the properties as a function of the preparation method was discussed. The photocatalytic performance of these solids was preliminarily tested for the degradation of 4-nitrophenol. The degradation pathway and the nature of the by-products were investigated by mass spectrometry. The solids showed good catalytic behaviour, although their preparation must be improved, mainly concerning the calcination step involved in sol–gel synthesis, which led to the formation of Mn₂O₃ that worsened the catalytic behaviour.

GRAPHICAL ABSTRACT

KEYWORDS:

• Birnessites
• 4-nitrophenol
• photocatalytic degradation
• sol–gel methodology
• 4-nitrophenol degradation

Acknowledgements

BG thanks a pre-doctoral grant from Universidad de Salamanca. AG thanks Santander Bank support through the Research Intensification Program.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was jointly funded by the Spanish Ministry of Economy and Competitiveness (MINECO) and the European Regional Development Fund (ERDF) [grant number MAT2016-78863-C2-R].