Abstract
Graphitic carbon nitride (g-C3N4) was used to enhance the photocatalytic activity of ZnO nanoparticles for the degradation of 5-fluorouracil (5-FU) cytostatic drug under UV-LED irradiation. CN/ZnO composites were synthetized by an easy one-pot thermal method, varying the g-C3N4 loading, i.e., from 10 to 67 wt% and a post-thermal exfoliation in air. The physicochemical and optical properties of the materials were analyzed by several techniques. CN/ZnO composites showed a coral-like structure of spherical ZnO wurtzite particles on the g-C3N4 structure. In general, the synergism and heterojunction interface between both phases allowed the enhancement of the mesoporosity, light absorption ability, and the aromaticity of the corresponding composites. Moreover, the photocatalytic activity of the CN/ZnO composites was increased with the addition of g-C3N4 in comparison with pristine ZnO. The highest activity was found for the composite containing 25 wt% of g-C3N4 (i.e., CN25/ZnO), reaching the total degradation of 5-FU and a mineralization of 48% at 180 min, as well as a good photostability during four reuse cycles. Experiments with different pH solutions and scavengers allowed for the assessment of the reactive oxygen species (ROS) involved in the 5-FU degradation pathway, with radicals and non-radical species as the main responsible active species. Furthermore, a tentative photocatalytic mechanism was proposed for CN/ZnO composites.
Highlights
Accepted: 18 January 2022An intensive agriculture and livestock activity, as well as increased industrial discharges and a growing population play a prominent role in the decrease of natural water resources quality
The analysis of the different spectral indicating smaller interactions between the phases in this sample. These results point out regions pointed out the stronger similarity of CN67/Zinc oxide (ZnO) with the pure phases, indicating that the formation heterojunctions both semiconductors is favored at g-C3N4 smaller interactionsofbetween the phasesbetween in this sample
Text,obtained the obtained results indicate the highest photocatalytic activity of the composites the results indicate that that the highest photocatalytic activity of the composites is obtained at natural pH values, since the 5-FU removal increased as the media pH value from pH 3.0 to 6.3 (48.3% and 100.0%, respectively)
Summary
An intensive agriculture and livestock activity, as well as increased industrial discharges and a growing population play a prominent role in the decrease of natural water resources quality. Graphitic carbon nitride (g-C3 N4 ) has emerged as an interesting photocatalyst due to its effective light harvesting, accompanied by a narrow band gap (i.e., 2.7 eV) and high photocatalytic activity for the degradation of different organic pollutants in aqueous solution [8]. This polymeric semiconductor presents strong carbon–nitrogen covalent bonds providing a high chemical and thermal stability and high electronic conductivity due to a delocalized conjugated structure [9]. Additional photocatalytic experiments using different scavengers and consecutive reaction cycles were carried out to assess the possible reaction mechanism and the photocatalyst stability, respectively
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