Synthesis, Characterization, and Application of Pt/PtO2-TiO2/SiO2 Materials on a Continuous Flow Packed Bed Microreactor for Enhanced Photocatalytic Activity under Sunlight

Author(s)

Gusmao, Carolina de Araujo ; Borges, Laura Teixeira ; Palharim, Priscila Hasse ; Otubo, Larissa ; Rodrigues, Orlando ; Gouvea, Douglas ; Ramos, Bruno ; Silva Costa Teixeira, Antonio Carlos

• Document type: Journal article
• Source: WATER; v. 14, n. 23, p. 18-pg., 2022-12-01.

Abstract

The present work aimed at the development of Pt-TiO2/SiO2 materials applied to the degradation of a pharmaceutical pollutant in a fixed-bed microreactor in continuous mode. First, a wide investigation of the optimal platinum content in TiO2/SiO2 was carried out based on extensive characterization through XRD, DRS, SEM, TEM, and XPS techniques. For the content range studied, no significant changes were observed in the crystallinity of the material, with peaks related to the anatase phase and PtO2 in the diffractograms. SEM images combined with EDS spectra indicated the presence of platinum and a large heterogeneity in the particles. MET analyses showed PtO2 nanoparticles in close contact with TiO2, allowing the formation of a type II heterojunction. XPS showed platinum in the 0 and +4 oxidation states, suggesting that platinum metal and PtO2 are both present. Regarding the degradation experiments, the optimal catalyst achieved 81% degradation of acetaminophen for a residence time of 1 h, while the catalyst without platinum reached only 27% degradation. The catalyst activity dropped from 81 to 57% in 2 h and remained stable for six reuse cycles. Increasing the inlet flow rate and concentration reduced the pollutant degradation although there was an increase in the reaction rate. Finally, a photocatalytic mechanism was proposed in which a type II heterojunction was developed, with generation of hydroxyl radicals by the positive holes in the VB of TiO2 as well as superoxide radicals by the electrons in the CB of PtO2. (AU)

• FAPESP's process: 21/10919-8 - Design and fabrication of microfluidic devices for thermal and electrochemical CO2 processing
• Grantee: Bruno Ramos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/24158-9 - Environmental fate of emerging pollutants in surface waters and sustainable alternatives for their mitigation: a hybrid experimental & theoretical approach
• Grantee: Antonio Carlos Silva Costa Teixeira
• Support Opportunities: Regular Research Grants
• FAPESP's process: 22/12331-0 - Synthesis and characterization of Pt-TiO2/SiO2 materials and evaluation in a fixed bed continuous photocatalytic reactor for the degradation of pharmaceutical compounds
• Grantee: Laura Teixeira Borges
• Support Opportunities: Scholarships in Brazil - Scientific Initiation