Boosted Activity of g-C3N4/UiO-66-NH2 Heterostructures for the Photocatalytic Degradation of Contaminants in Water

Abstract

The combination of graphitic carbon nitride and the metal-organic framework UiO-66-NH2 has been developed with the aim to enhance the photocatalytic activity of pure semiconductors. Different proportions of g-C3N4 and UiO-66-NH2 were combined. Complete characterization analysis of the resulting photocatalytic materials was conducted, including N2 adsorption isotherms, XRD, FTIR, STEM-EDX microscopy, DRS-UV-visible, and photoluminescence. The photocatalytic activity was tested in an aqueous solution for the removal of acetaminophen as the target pollutant. From the obtained results, less than 50% of UiO-66-NH2 incorporated in the g-C3N4 structure enhanced the photocatalytic degradation rate of both bare semiconductors. Concretely, 75% of g-C3N4 in the final g-C3N4/UiO-66-NH2 heterostructure led to the best results, i.e., complete acetaminophen elimination initially at 5 mg·L−1 in 2 h with a pseudo-first order rate constant of ca. 2 h−1. The presence of UiO-66-NH2 in the g-C3N4 enhanced the optoelectronic properties, concretely, the separation of the photo-generated charges was improved according to photoluminescence characterization. The better photo-absorption uptake was also confirmed by the determination of the quantum efficiency values of the heterostructure if compared to either pure g-C3N4 or UiO-66-NH2. This photocatalyst with the best activity was further tested at different pH values, with the best degradation rate at a pH close to the pHpzc ~4.15 of the solid. Sequential recycling tests demonstrated that the heterostructure was stable after five cycles of use, i.e., 15 h. A high contribution of photo-generated holes in the process of the degradation of acetaminophen, followed marginally by superoxide radicals, was suggested by scavenger tests.

Recent advances in removal of pharmaceutical pollutants in wastewater using metal oxides and carbonaceous materials as photocatalysts: a review

“…Therefore, attention has focused on its removal from aqueous media following a photocatalysis approach, as described below. 79–147…”

Photocatalytic Degradation of Acetaminophen in Aqueous Environments: A Mini Review

“…In addition, g-C 3 N 4 /UiO-66-NH 2 photocatalyst, a highly efficient type-II heterojunction, was synthesized by incorporation of g-C 3 N 4 with MOF UiO-66-NH 2 [ 120 ]. After 240 min of photocatalytic reaction, 5 mg/L ACT could be completely degraded by g-C 3 N 4 /UiO-66-NH 2 photocatalyst.…”

“…The chemical stability of photocatalysts can be verified by recycling experiments. In addition, analyzing the Fourier transform infrared spectra (FT-IR) and X-ray diffraction (XRD) of the photocatalysts before and after the photocatalytic reaction are effective in investigating their chemical stability [ 103 , 105 , 120 ].…”

Ruthenium Deposited Onto Graphitic Carbon Modified with Boron for the Intensified Photocatalytic Production of Benzaldehyde

“…The NaBCN-Ru catalysts were tested for the selective photocatalytic oxidation of benzyl alcohol to benzaldehyde in a borosilicate glass annular jacketed photoreactor equipped with two UVA lamps emitting at 365 nm (9 W each). Detailed information on the experimental setup can be found in a previous work [21]. The lamps were centered in the inner space and the aqueous solution with the slurry catalyst was circulating by the jacketing space.…”

“…where r BA,0 was estimated from the slope of the temporal evolution of the C BA with the tangent at the initial reaction time. The determination of the photon absorption rate (e α,ν ), and the radiative transfer equation (RTE) was solved considering the geometry of the used photoreactor [21]. Firstly, the determination of the optical properties of the catalytic suspensions is required.…”