Design of a ternary magnetic composite based on a covalent organic framework and Ag nanoparticles for simultaneous photodegradation of organic pollutants under LED light irradiation: Application of BBD-RSM modeling and resolution of spectral overlap of analytes

Abstract

Designing novel photocatalysts is crucial in improving pollutant removal and promoting a cleaner and healthier environment. The main objective of this study was to create a novel magnetic core-shell structure that could be used for photocatalytic applications. To achieve this goal, we used CoFe2O4 magnetic nanoparticles as the core and a covalent organic framework (COF) as the shell, which was designed to have magnetic properties and a suitable surface for further functionalization. To improve its photocatalytic properties, we added silver nanoparticles (Ag NPs) by a facile light-assisted reduction process to create a ternary composite. The presence of Ag NPs is expected to result in a broader absorption range of light and more effective degradation of pollutants through plasmonic sensitization and the transfer of bandgap energy into the visible light spectra. We characterized the prepared composite using various chemical and physical techniques, and then examined its ability to remove two stable organic pollutants, methylene blue (MB) dye and 4-nitrophenol (4-NP), simultaneously. The strong spectral overlap between these pollutants posed a challenge for conventional spectroscopic methods to accurately measure their concentration. To overcome this, a rapid and new method, namely extended ratio subtraction method (EXRSM), was utilized to separate and remove the spectral overlap. We further optimized the reaction conditions using response surface methodology (RSM) modeling techniques. Our findings indicated that the designed composite was capable of degrading organic pollutants under the visible light radiation of an LED lamp.