Photocatalytic oxidation of pharmaceutical contaminants of emerging concern using sunlight and visible radiation: Mechanism and ecotoxicological evaluation

Water scarcity is a worldwide problem boosted by global warming and pollution of anthropogenic origin. The contaminants of emerging concern in water sources are increasing due to the inefficiency of conventional wastewater treatments, and these should be mitigated. Advanced oxidation processes appear as suitable solutions for decontamination. The photocatalytic oxidation of the mixture of sulfamethoxazole, carbamazepine and lorazepam was investigated. TiO2 modified by Ag and TiO2 modified by Pd were used as photocatalysts to improve photoactivity. The impact of light wavelengths was examined using UVA and visible radiation as well as natural sunlight. Visible light revealed the lowest ability for decontamination in 60 min of irradiation through Ag and Pd–TiO2 photocatalytic oxidation. On the other hand, UVA and sunlight in the presence of photocatalysts were able to totally remove the contaminants. This can be related to the high production of reactive oxidative species at those conditions. The increase of the noble metal load promotes the improvement of the decontamination efficiency. The kinetic rate was analyzed for UVA and sunlight radiation for different photocatalytic conditions. The presence of a natural light source without energy costs leads to an increase in the pseudo-first-order kinetic constant. Sunlight radiation with a suitable photocatalyst can be a very good option for water decontamination.

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Iron-based catalysts under solar and visible radiation for contaminants of emerging concern removal

Energy Reports ◽

10.1016/j.egyr.2019.09.054 ◽

2020 ◽

Vol 6 ◽

pp. 711-716 ◽

Cited By ~ 1

Author(s):

Eva Domingues ◽

João Gomes ◽

Nelson Assunção ◽

Marta Gmurek ◽

Margarida J. Quina ◽

...

Keyword(s):

Contaminants Of Emerging Concern ◽

Visible Radiation ◽

Iron Based ◽

Iron Based Catalysts

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Pharmaceutical contaminants of emerging concern in the environment

Environmental Toxicology and Chemistry ◽

10.1002/etc.2293 ◽

2013 ◽

Vol 32 (8) ◽

pp. 1683-1684 ◽

Cited By ~ 7

Author(s):

Chris D. Metcalfe

Keyword(s):

Contaminants Of Emerging Concern ◽

Pharmaceutical Contaminants

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Insights into the Stability and Activity of MIL-53(Fe) in Solar Photocatalytic Oxidation Processes in Water

Catalysts ◽

10.3390/catal11040448 ◽

2021 ◽

Vol 11 (4) ◽

pp. 448

Author(s):

Jorge López ◽

Ana M. Chávez ◽

Ana Rey ◽

Pedro M. Álvarez

Keyword(s):

Hydrogen Peroxide ◽

Solar Radiation ◽

Photocatalytic Oxidation ◽

Diffuse Reflectance Spectroscopy ◽

Metal Organic Framework ◽

Visible Radiation ◽

X Ray ◽

Metal Organic ◽

The Stability ◽

Organic Framework

MIL-53(Fe) is a metal organic framework that has been recently considered a heterogeneous photocatalyst candidate for the degradation of water pollutants under visible or solar radiation, though stability studies are rather scarce in the literature. In this work, MIL-53(Fe) was successfully synthesized by a solvothermal method and fully characterized by X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), N2 adsorption–desorption isotherm, Thermogravimetric analysis coupled with mass spectrometry (TGA-MS), UV-visible diffuse reflectance spectroscopy (DRS), elemental analysis and wavelength dispersive X-ray fluorescence (WDXRF). The effects of pH, temperature, solar radiation and the presence of oxidants (i.e., electron acceptors) such as ozone, persulfate and hydrogen peroxide on the stability of MIL-53(Fe) in water were investigated. The as-synthetized MIL-53(Fe) exhibited relatively good stability in water at pH 4 but suffered fast hydrolysis at alkaline conditions. At pH 4–5, temperature, radiation (solar and visible radiation) and oxidants exerted negative effect on the stability of the metal–organic framework (MOF) in water, resulting in non-negligible amounts of metal (iron) and linker (terephthalic acid, H2BDC) leached out from MIL-53(Fe). The photocatalytic activity of MIL-53(Fe) under simulated solar radiation was studied using phenol and metoprolol as target pollutants. MIL-53(Fe) on its own removed less than 10% of the pollutants after 3 h of irradiation, while in the presence of ozone, persulfate or hydrogen peroxide, complete elimination of pollutants was achieved within 2 h of exposure to radiation. However, the presence of oxidants and the formation of some reaction intermediates (e.g., short-chain carboxylic acids) accelerated MIL-53(Fe) decarboxylation. The findings of this work suggest that MIL-53(Fe) should not be recommended as a heterogeneous photocatalyst for water treatment before carrying out a careful evaluation of its stability under actual reaction conditions.

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Photocatalytic Oxidation of Five Contaminants of Emerging Concern by UV/TiO2: Identification of Intermediates and Degradation Pathways

Environmental Engineering Science ◽

10.1089/ees.2015.0388 ◽

2016 ◽

Vol 33 (2) ◽

pp. 140-147 ◽

Cited By ~ 8

Author(s):

Jose R. Alvarez-Corena ◽

John A. Bergendahl ◽

Fred L. Hart

Keyword(s):

Photocatalytic Oxidation ◽

Degradation Pathways ◽

Contaminants Of Emerging Concern

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Near-field scanning optical microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144644 ◽

1986 ◽

Vol 44 ◽

pp. 642-643

Author(s):

E. Betzig ◽

A. Harootunian ◽

M. Isaacson ◽

A. Lewis

Keyword(s):

Near Field ◽

Optical Microscope ◽

Visible Radiation ◽

Field Methods ◽

Optical Elements ◽

Optical Region ◽

Order Of Magnitude ◽

Nondestructive Imaging ◽

Scanning Optical Microscopy ◽

Near Field Scanning

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.

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