Plasma electrolytic oxidation in new environmental remediation technologies

• Grant number: 24/07206-8
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2024
• End date: June 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Ernesto Chaves Pereira de Souza
• Grantee: Kelvin Costa de Araújo
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil
• Associated research grant: 13/07296-2 - CDMF - Center for the Development of Functional Materials, AP.CEPID

Abstract

We propose the novel use of Plasma Electrolytic Oxidation (PEO) directly in the degradation of contaminants in environmental samples. This approach relies on electrical discharges in the form of sparks observed on the surface of the working electrode. A spark is a local phenomenon that can reach temperatures exceeding 3000 K for a few milliseconds. PEO, also known as anodization by sparks, is commonly employed to prepare metal oxide films, primarily using titanium, niobium, aluminum, and zirconia as substrates. The process can be conducted either galvanostatically, with the application of constant current, or potentiostatically, with the constant application of voltage, in two-electrode systems, with oxide film formation occurring at the anode. The use of chemometric knowledge to optimize the formation of oxide films and consequently the sparks will be vital and can contribute to various studies conducted at CDMF. The objective of this study is to evaluate the potential use of PEO as a new environmental remediation technology, employing chemometric knowledge for optimization, desirability, and monitoring. In addition, making these techniques available for various ongoing studies at CDMF. It is described in the literature that different conditions can result in different morphologies of the material obtained by PEO. To optimize the process's potential for degrading organic contaminants, we will conduct an experimental design. Initially, we propose to conduct a screening of various conditions that may exhibit variability in synthesized material using the Plackett-Burman design, which, being a saturated design, allows the evaluation of a large number of variables with a reduced number of experiments. Following the screening, we will optimize using a Central Composite Design (CCD), allowing us to evaluate different variable conditions and their primary interactions. Degradation tests will be conducted on a laboratory-prepared drug mixture. We will optimize the degradation process for the drug mixture before applying it to environmental matrices: surface waters and effluents. In this study, three variables will be evaluated: electrode area, degradation time, and metal used. The environmental samples will be collected from the Jacaré-guaçú river in the regions near the Broa dam, in Itirapina - SP, and in Gavião Peixoto, also in the state of São Paulo. Effluent will be collected from sewage treatment plants in municipalities around the São Carlos-Araraquara region of São Paulo. We anticipate obtaining an optimized PEO process for environmental remediation, targeting the degradation of organic contaminants, initially focusing on pharmaceuticals. Subsequently, we will apply the degradation process to environmental samples. Additionally, we expect to consolidate the use of chemometric approaches by other CDMF members to obtain materials with optimized conditions for various processes of interest. (AU)