Photoelectrodegradation of ciprofloxacin using Ti-O-Nb nanotubular oxides in varied compositions as photocatalyst

• Grant number: 24/08865-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2024
• Effective date (End): April 30, 2025
• Field of knowledge: Engineering - Sanitary Engineering - Water Supply and Wastewater Treatment
• Principal Investigator: Christiane de Arruda Rodrigues
• Grantee: Helena Romann Tambelli
• Host Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil
• Associated research grant: 21/10599-3 - The Antimicrobial Resistance Institute of São Paulo (The Aries Project), AP.CEPID

Abstract

The release of antibiotics into the environment can lead to chronic toxicity and the development of antimicrobial resistance. The photoelectrocatalysis (PEC) process has been shown to be effective in the degradation of organic compounds when generally using metallic oxides as semiconductors. TiO2 is one of the most used semiconductors due to its low toxicity, high photochemical reactivity, and high mechanical and corrosion resistance. However, its efficiency is limited by low visible light excitation and the high recombination rate of the photogenerated electron/hole pair. One way to overcome these shortcomings is the production of self-organized mixed oxides, such as the Nb-O-Ti system. In this arrangement, Nb oxides can be in different oxidation states (2+, 4+ or 5+), favoring the reduction of the TiO2 recombination rate and allowing the use of visible light. Considering the importance of the material for PEC efficiency, this work aims to obtain self-organized oxides of the Nb-O-Ti system from the Ti-xNb alloy (x = 2, 7, 14 and 22% m/m), followed by heat treatment and use in the degradation of the antibiotic ciprofloxacin. The synthesis of Ti-O-Nb nanotubular electrodes will be carried out using an anodization process, under conditions previously optimized in studies by the research group of which this project is inserted. The materials will be characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), reflectance spectrometry (DRS) and electrochemical techniques (in the absence and presence of UV radiation). The heat treatment will aim to obtain crystallinity with high photoactivity under UV-Vis light. Ciprofloxacin removal tests via photolysis, photocatalysis and photoelectrocatalysis will be carried out in a photoelectrochemical reactor and the pollutant decay rate will be analyzed using high-performance liquid chromatography (HPLC). The results will be compared to find the best composition of the Ti-Nb alloy and the substrate preparation conditions (annealed or tempered) to be used in the treatment of effluents or contaminated water, allowing the reuse of industrial water and water supply with quality to the population. The evaluation of the antimicrobial activity of byproducts generated in the degradation process will also be carried out. In the optimized condition, concerning the photoelectrode, tests will be carried out with a water supply enriched with ciprofloxacin to evaluate the interference of the real matrix.