Synthesis, characterization and application of heterojunctions of Ag3PO4/KNbO3 semiconductor oxides in the oxidation of microplastics by photocatalytic, photoelectrocatalytic and modified membranes methods

• Grant number: 22/14679-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2023
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Maria Valnice Boldrin
• Grantee: Rodrigo de Mello
• Host Institution: Instituto de Química (IQ). Universidade Estadual Paulista (UNESP). Campus de Araraquara. Araraquara , SP, Brazil
• Associated research grant: 14/50945-4 - INCT 2014: National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactivies, AP.TEM
• Associated scholarship(s): 25/01477-2 - Development of photoelectrodes based on semiconductor oxide heterojunctions for photo electrooxidation of microplastics: nanocomposites based on TiO2, WO3, Ag3PO4, and KNbO3, BE.EP.PD

Abstract

The versatile use of plastics in the modern world has led to many concerns about their disposal in the environment, especially because of the possible pollution of fresh and marine waters. The demand for studies dealing with these compounds primarily concerns those that result from their fragmentation, such as microplastics. These compounds, with extremely small particles, have caused numerous problems and have affected their removal during drinking water treatment. Given the increasing concern about these compounds in water bodies, this project proposes to investigate new methods for treating water contaminated by polypropylene (PP) and polyethylene (PE), which are models for constituents of microplastics used extensively in industry. For this, photocatalytic and photoelectrocatalytic methods will be used, as well as membranes modified with semiconductors, the latter with the aim of combining the efficiency of filtration and degradation processes, since these materials are capable of also promoting the oxidation of these pollutants when coupled to photoelectrocatalytic techniques. As photo(electro)catalytic materials, heterojunctions of semiconductor oxides based on Ag3PO4/KNbO3 are proposed to be developed to improve the stability and efficiency of these photocatalysts and to study their efficiency in photoactivation under visible light. The synthesized materials will be used in photocatalytic treatment (solution and modified membranes) of solutions containing PP and PE with controlled sizes, optimizing the type of irradiation (UV, visible or UV/visible). In photoelectrocatalysis treatments, the semiconductor is deposited on a semiconductor substrate or a conductive filtration membrane modified with Ag3PO4/KNbO3 semiconductors, and the irradiation is coupled to an external potential, according to the system previously developed by this research group. The efficiency of each methodology will be evaluated by monitoring the contaminant during degradation by scanning electron microscopy (SEM), gas chromatography with pyrolysis, FTIR and measurements of total organic carbon removal, observing particle size reduction, production of monomers from the degradation of polymers, degradation of monomers, reduction of organic matter to CO2 and minerals, respectively. The project is an important part of the development of the INCT-DATREM project (FAPESP n. 2014/50945-4) and will contribute to advancing knowledge about a broad and emerging problem in the modern world.