Abstract
In the present work, the performance of Ag/ZnO/CoFe2O4 magnetic photocatalysts in the photocatalytic degradation of ibuprofen (IBP) was evaluated. This study considered the use of pure Ag/ZnO (5% Ag) and also the use of the Ag/ZnO/CoFe2O4 magnetic catalysts containing different amounts (5, 10 and 15% wt) of cobalt ferrite (CoFe2O4). The catalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoacoustic spectroscopy. To carry out the photocatalytic degradation reaction, different concentrations of the ibuprofen contaminant solution (10, 20 and 30 ppm) and different concentrations of photocatalyst were tested (0.3 g L-1, 0.5 g L-1 and 1.0 g L-1). The reaction parameters studied were: IBP concentration, catalyst concentration, adsorption and photolysis, influence of the matrix, radiation source (solar and artificial) and the effect of organic additive. At the end of the photocatalytic tests, the best operating conditions were defined. Considering the obtained results of degradation efficiency and magnetic separation, the optimal parameters selected to proceed with the other tests of the study were: ibuprofen solution concentration 10 ppm, Ag/ZnO/CoFe2O4 (5%) catalyst at a concentration of 0.3 g L-1 and pH 4.5 of the reaction medium. The results indicated the feasibility of magnetic separation of the synthesized catalysts. A long duration test indicated that the catalyst exhibits stability throughout the degradation reaction, as more than 80% of IBP was degraded after 300 minutes. The photocatalytic activity was directly affected by the ferrite load. The higher the nominal load of ferrite, the lower the performance in IBP degradation. It was also observed that the smallest amount of ferrite studied was enough for the catalyst to be recovered and reused. The adsorption and photolysis tests did not show significant results in the IBP degradation. In addition, it was possible to verify that the aqueous matrix, the use of solar radiation and the addition of additive (acid formic) were interfered directly in the process. The catalyst reuse tests indicated that it can be recovered and reused at least three times without considerable catalytic activity loss.
Highlights
The drugs comprise a variety of products used for the most diverse diseases
The magnetic particles coated with Ag/zinc oxide (ZnO) were still magnetic, since they were affected by the presence of the magnet (Figure 2)
This effect of zinc oxide coating on the magnetic response of the particles was already expected, to that previously reported by Fu et al for TiO2/CoFe2O4 particles, whose coercivity and specific magnetization considerably decreased as the TiO2 percentage in the samples increased (Fu et al 2005)
Summary
The drugs comprise a variety of products used for the most diverse diseases. Among the prescribed anti-inflammatory drugs, which are more than 70 million prescriptions per year (Macedo et al 2021), there is the drug ibuprofen (IBP). ibuprofen is a drug formed by a chiral compound derived from arylpropionic acid, and is considered a non-steroidal and non-narcotic antiinflammatory, this substance has been available since 1984 without a prescription, and can be freely administered to thousands of people all the days (Dasgupta & Krasowski 2020).In a period of 24 hours after being consumed, ibuprofen is excreted in human and animal urine and will subsequently be present in wastewater, which, if disposed of incorrectly or without proper treatment, may end up reaching surface water and (Dasgupta & Krasowski 2020; Jia et al 2021; Ren et al 2021).According to Ren et al (2021), ibuprofen has been detected in surface waters and effluents since 2011, in varying concentrations ranging from 1,317 nm LÀ1 to 17,600 ng LÀ1. Ibuprofen is a drug formed by a chiral compound derived from arylpropionic acid, and is considered a non-steroidal and non-narcotic antiinflammatory, this substance has been available since 1984 without a prescription, and can be freely administered to thousands of people all the days (Dasgupta & Krasowski 2020). In a period of 24 hours after being consumed, ibuprofen is excreted in human and animal urine and will subsequently be present in wastewater, which, if disposed of incorrectly or without proper treatment, may end up reaching surface water and (Dasgupta & Krasowski 2020; Jia et al 2021; Ren et al 2021). The authors report that, at low concentrations, the life of the ecosystem present in the receiving surface waters must be taken into account, carrying out studies that completely remove components called emerging contaminants such as ibuprofen. Heterogeneous photocatalysis has shown to be a promising process in the removal of organic contaminants (Candido et al 2016)
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