A titanium-based photo-Fenton bifunctional catalyst of mp-MXene/TiO2−x nanodots for dramatic enhancement of catalytic efficiency in advanced oxidation processes

2018 ◽  
Vol 54 (82) ◽  
pp. 11622-11625 ◽  
Author(s):  
Xiaomei Cheng ◽  
Lianhai Zu ◽  
Yue Jiang ◽  
Donglu Shi ◽  
Xiaoming Cai ◽  
...  

A pseudo-Fenton reaction works synergistically with photocatalysis to greatly accelerate the oxidative degradation rate.

Author(s):  
Zahia Benredjem ◽  
Karima Barbari ◽  
Imene Chaabna ◽  
Samia Saaidia ◽  
Abdelhak Djemel ◽  
...  

Abstract The Advanced Oxidation Processes (AOPs) are promising environmentally friendly technologies for the treatment of wastewater containing organic pollutants in general and particularly dyes. The aim of this work is to determine which of the AOP processes based on the Fenton reaction is more effective in degrading the methyl orange (MO) dye. The comparative study of the Fenton, photo-Fenton (PF) and electro-Fenton (EF) processes has shown that electro-Fenton is the most efficient method for oxidizing Methyl Orange. The evolution of organic matter degradation was followed by absorbance (discoloration) and COD (mineralization) measurements. The kinetics of the MO degradation by the electro-Fenton process is very rapid and the OM degradation rate reached 90.87% after 5 min. The influence of some parameters such as the concentration of the catalyst (Fe (II)), the concentration of MO, the current density, the nature and the concentration of supporting electrolyte was investigated. The results showed that the degradation rate increases with the increase in the applied current density and the concentration of the supporting electrolyte. The study of the concentration effect on the rate degradation revealed optimal values for the concentrations 2.10−5 M and 75 mg L−1 of Fe (II) and MO respectively.


2021 ◽  
Author(s):  
Qiaobo Liao ◽  
Can Ke ◽  
Dongni Wang ◽  
Yiying Zhang ◽  
Qingwen Han ◽  
...  

The Fenton reaction is one of the most efficient and widely used advanced oxidation processes for remediating the ever-growing water pollution. Metal-free photocatalysts for Fenton-like reactions have gathered enormous scientific interest for their advantages including board pH operation range and high stability. Herein, we demonstrate a metal-free covalent organic framework (COF)-based standalone photocatalyst with superior reactivity and reusability for Fenton-like reactions at acid and neutral pH solutions, which can be attributed to its large porosity, high density of the photoactive triazine moiety, vertical π arrays formed by eclipsed layer stacking and the <i>β</i>‑ketoenamine linkage. Our experiments showed that the photocatalyst can absorb visible light effectively for activation of H<sub>2</sub>O<sub>2</sub>, producing abundant reactive oxygen species including superoxide radical (O<sub>2</sub><sup>·-</sup>), hydroxyl radical (<sup>·</sup>OH), and singlet oxygen (<sup>1</sup>O<sub>2</sub>) for oxidizing organic pollutants. This work not only provides an efficient metal-free photocatalyst for Fenton-like reactions, but also paves the way for COFs towards advanced oxidation processes, opening up the possibilities to their future applications in industry.


2008 ◽  
Vol 58 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
C. von Sonntag

The reactive intermediate in Advanced Oxidation Processes (AOPs) is the •OH radical. It may be generated by various approaches such as the Fenton reaction (Fe2 + /H2O2), photo-Fenton reaction (Fe3 + /H2O2/hν), UV/H2O2, peroxone reaction (O3/H2O2), O3/UV, O3/activated carbon, O3/dissolved organic carbon (DOC) of water matrix, ionizing radiation, vacuum UV, and ultrasound. The underlying reactions and •OH formation efficiencies are discussed. The key reactions of •OH radicals also addressed in this review.


2011 ◽  
Vol 171 (1) ◽  
pp. 127-135 ◽  
Author(s):  
Mehmet A. Oturan ◽  
Nihal Oturan ◽  
Mohamed C. Edelahi ◽  
Fetah I. Podvorica ◽  
Kacem El Kacemi

2001 ◽  
Vol 44 (5) ◽  
pp. 39-46 ◽  
Author(s):  
S. Contreras ◽  
M. Rodríguez ◽  
E. Chamarro ◽  
S. Esplugas ◽  
J. Casado

The degradation of nitrobenzene using some advanced oxidation processes (O3/UV, O3/UV/H2O2 and O3/UV/Fe(III)) has been investigated. In the combined O3/UV process, the effect of pH and ozone was studied. In the other combinations, the influence of the amount of hydrogen peroxide and ferric ion in the degradation rate and TOC evolution, has been studied. Under our conditions, the combination O3/UV did not improve the degradation rate obtained by ozonation. The best TOC decrease was obtained when the O3/UV process was carried out at low ferric ion concentrations.


Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3035
Author(s):  
Xinlu Qu ◽  
Haowei Wu ◽  
Tianyang Zhang ◽  
Qianhong Liu ◽  
Mu Wang ◽  
...  

As an emerging light source, ultraviolet light emitting diodes (UV-LEDs) are adopted to overcome the shortcomings of the conventional mercury lamp, such as mercury pollution. The degradation of chloramphenicol (CAP) using three UV-LED-based advanced oxidation processes (AOPs)—UV-LED/persulfate (UV-LED/PS), UV-LED/peroxymonosulfate (UV-LED/PMS) and UV-LED/chlorine—was investigated. Results indicate that CAP can be more effectively degraded by the hybrid processes when compared to UV irradiation and oxidants alone. Degradation of CAP using the three UV-LED-based AOPs followed pseudo-first-order kinetics. The degradation rate constants (kobs) for UV-LED/PS, UV-LED/PMS, and UV-LED/chlorine were 0.0522, 0.0437 and 0.0523 min−1, and the CAP removal rates 99%, 98.1% and 96.3%, respectively. The degradation rate constant (kobs) increased with increasing oxidant dosage for UV-LED/chlorine, whereas overdosing reduced CAP degradation using UV-LED/PS and UV-LED/PMS. Ultraviolet wavelength influenced degradation efficiency of the UV-LED based AOPs with maximum CAP degradation observed at a wavelength of 280 nm. The application of UV-LED enhanced the formation DBPs during subsequent chlorination. uUV-LED/PMS produced more disinfection by-products than UV-LED/PS. Compared to UV-LED, UV-LED/PS reduced the formation of dichloroacetonitrile and trichloronitromethane during chlorination owing to its capacity to degrade the nitro group in CAP. The intermediates dichloroacetamide, 4-nitrobenzoic acid, 4-nitrophenol were produced during the degradation of CAP using each of UV-LED, UV-LED/PS and UV-LED/chlorine. The present study provides further evidence supporting the application of UV-LED in AOPs.


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