Characterization of magnetic photocatalyst with environmental applications

MORALES, MA. GISELA; ESCALADA, JUAN PABLO; APARICIO, FRANCISCA; PAJARES, ADRIANA

Encuentro; XIV Encuentro Latinoamericano de Fotoquímica y Fotobiología (ELAFOT); 2019

Heterogeneous photocatalysis has rapidly emerged as the most attractive AOP (Advanced Oxidation Processes) in recent years for the destruction of organic, inorganic, and microbial pollutants due to a number of advantages, such as its versatile nature in terms of the variety of pollutants that can be removed, the potential to completely mineralize organic pollutants, the ability to use solar radiation in some cases to reduce the operational costs, and its capacity of being reused in several treatment cycles.1 However, some limitations regarding recovery and reuse of the photocatalysts have inhibited their application in real systems. This issue can be overcome providing magnetic properties to the photocatalysts allowing an efficient separation and recovery with an external magnetic field. In this work, magnetic nanocomposites were developed to be used as photocatalysts in photochemical treatments for the degradation of pollutants from wastewater. Ag/Fe3O4 nanocomposites (NCs) were synthesized using starch as both a biocompatible capping agent for Fe3O4 nanoparticles and a reducing agent for the reduction of silver ions in an alkaline medium2 and an one-pot method through the redox reaction between Ag2O and Fe(OH)2 in absence of additional reductant.3The NCs were thoroughly characterize by Fourier transform infrared spectroscopy (FT-IR), UV-Vis diffuse reflectance spectroscopy (DRS) and Laser flash-photolysis (LFP) experiments for Transient Absorption Spectroscopy. The capacity of the as-prepared NCs for the generation of reactive species under UVA light was evaluated by laser flash photolysis (LFP) experiments.FT-IR spectra showed interaction between Fe3O4-starch and Fe3O4-PVP nanoparticles, organic functional groups from starch and bands assigned of the Fe-O, C-O, C-H and O-H bonds. The diffuse reflectance spectra (DRS) of the Ag-Fe3O4 nanomaterials evidenced a similarity between them, but different from that expected for a semiconductor material. Instead of an increase in reflectance in the region of higher wavelengths of the spectrum, they all have a wide band centered around 230 nm, a smaller one centered at 330 nm, and then, the intensity of the reflectance decreases homogeneously 400 to 800 nm. LFP showed the characteristic broad absorption assigned to the electron-hole pair.