Sol-gel and Pechini niobium modified: synthesis, characterization and application in the 2,4-D herbicide degradation

Abstract

In this work, a comparison was made between the synthesis of niobium-based materials (Nb2O5), both in terms of material characterization and catalytic performance. The methods used were chemical mixtures: modified sol-gel and Pechini. The materials were calcined at different temperatures (753, 873 and 993K) and characterized by the following techniques: photoacousticspectroscopy (PAS), zero charge point (pHPZC), scanning electron microscopy (SEM/EDS), thermogravimetric analysis (TGA/DTG) and X-ray diffraction (XRD). The photocatalytic process was carried out to evaluate the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under UV radiation (250 W mercury vapor lamp) and different experimental conditions. In addition, to better understand the influence of parameters such as pH, catalyst concentration (0.2, 0.5 and 0.8 g L⁻¹) and calcination temperature, a Design of Experiments (DoE) was used. The results indicated that despite having similar structures and phases in the XRD analysis, the morphology presents two distinct surfaces, due to the preparation method. Differences in the synthesis method affected the catalytic activity in the parameters studied. Although the zero charge point values are close (6.18-6.36), we observed differences in the band gap depending on the calcination temperature. In the optimal condition studied, the catalyst prepared by the sol-gel method obtained the best results.

Keywords:

• Heterogeneous photocatalysis
• 2,4-dichlorophenoxyacetic acid
• chemical mixture method
• design of experiments (DoE)

Acknowledgments

The authors are thankful to the Brazilian Agencies CNPq, Fundação Araucária and CAPES for financial support of this work, C²MMa Laboratory in UTFPR-PG and Analysis Center Laboratory of UTFPR-PB, for the materials characterizations analysis.

Authors’ contributions

Y. B. Fávaro: Investigation, Methodology, Writing—original draft, Visualization, Data curation, M. Z. Fidelis, E. Abreu and R. Brackmann: Methodology, Writing—review and editing Maria E. K. Fuziki, A. M. Tusset: Data curation, Writing—review and editing. G. G. Lenzi: Conceptualization, Supervision, Writing—review and editing, Funding acquisition.

Disclosure statement

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

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.