Metal–Organic Framework MIL-101(Fe) Nanoparticles Decorated with Ag Nanoparticles for Regulating the Photocatalytic Phenol Oxidation Pathway for Cr(VI) Reduction

Abstract

Photocatalysis is a promising technology to treat dilute phenol-Cr(VI) mixture, where photo-induced electrons are commonly thought of as the main active species for Cr(VI) reduction. However, it generally depends on the surface adsorption to achieve efficient electron transfer. Meanwhile, the possible contribution of reductive quinone derivatives oxidized from phenol to Cr(VI) reduction has been rarely explored. The key is to explicitly understand the relation between the phenol oxidation pathway and Cr(VI) reduction. Herein, Ag/AgCl/MIL-101(Fe) prepared by directly loading Ag nanoparticles on MIL-101(Fe) was applied to the joint treatment of phenol and Cr(VI).The role of quinone derivatives in reducing Cr(VI) was revealed by excluding the surface adsorption. During the phenol oxidation, •OH radicals were more consumed in the initial stage for the ring-opening of phenol. Meanwhile, 1 O2 evolved from •O2gradually caused the accumulation of reductive quinone intermediates, which dramatically accelerated the Cr(VI) reduction afterwards. This study demonstrates the significance of controlling the evolution process of active oxygen species for the joint photocatalytic treatment of phenol-Cr(VI) mixture.

TiO2@MOF Photocatalyst for the Synergetic Oxidation of Microcystin-LR and Reduction of Cr(VI) in Aqueous Media

“…The detection wavelength was 238 nm. The Cr (VI) concentration was detected using a typically colorimetric method at 540 nm, as proposed by previous study [32].…”

“…Recently, it has been found that a rational complex of MOFs with various semiconductor nanoparticles is able to not only optimize the generation of active species but also boost catalytic performance. For instance, g-C 3 N 4 /MIL-101(Fe), g-C 3 N 4 /PDI@NH 2 -MIL-53(Fe), TiO 2 /MIL-100(Fe) and Ag/AgCl/MIL-101(Fe) have been designed and used as photocatalysts for the removal of Cr (VI) and organic pollutants, such as bisphenol A, tetracycline and carbamazepine [30][31][32][33]. However, to the best of our knowledge, there are still no reports on the synergetic removal of Cr (VI) and MC-LR.…”

Recent Progress in the Development of MOF-Based Photocatalysts for the Photoreduction of Cr(VI)

“…TEM images of (a) MIL-101­(Fe), (b) 0.5% Ag/AgCl/MIL-101­(Fe), (c) 1% Ag/AgCl/MIL-101­(Fe), and (d) 2% Ag/AgCl/MIL-101­(Fe). Reprinted with permission from ref . Copyright 2021 American Chemical Society.…”

“…Mechanism of the Cr (VI) photoreduction by Ag/AgCl/MIL-101­(Fe). Reprinted with permission from ref . Copyright 2021 American Chemical Society.…”

Simultaneous removal of Cr(vi) and TC over BiO1−XBr/CeVO4 S-scheme heterostructures: oxygen vacancy boosted charge separation and analysis of intermediates

“…The standard diphenylcarbazide (DPC) method was used to measure the concentration of Cr(VI). 44,45 Scavenging experiments were performed to investigate the influence of different active species during the photocatalytic process. 1.0 mmol L −1 ethylenediaminetetraacetic acid (EDTA), 1.0 mmol L −1 tert-butanol (BUOH), and 0.33 mmol L −1 benzoquinone (BQ) were utilized as scavengers of h + , hydroxyl radicals (˙OH), and superoxide radical anions (˙O 2 − ), respectively.…”