Treatment of organic pollutants by homogeneous and heterogeneous Fenton reaction processes

Abstract

Nowadays, the water ecosystem is being polluted due to the rapid industrialization and massive use of antibiotics, fertilizers, cosmetics, paints, and other chemicals. Chemical oxidation is one of the most applied processes to degrade contaminants in water. However, chemicals are often unable to completely mineralize the pollutants. Enhanced pollutant degradation can be achieved by Fenton reaction and related processes. As a consequence, Fenton reactions have received great attention in the treatment of domestic and industrial wastewater effluents. Currently, homogeneous and heterogeneous Fenton processes are being investigated intensively and optimized for applications, either alone or in a combination of other processes. This review presents fundamental chemistry involved in various kinds of homogeneous Fenton reactions, which include classical Fenton, electro-Fenton, photo-Fenton, electro-Fenton, sono-electro-Fenton, and solar photoelectron-Fenton. In the homogeneous Fenton reaction process, the molar ratio of iron(II) and hydrogen peroxide, and the pH usually determine the effectiveness of removing target pollutants and subsequently their mineralization, monitored by a decrease in levels of total organic carbon or chemical oxygen demand. We present catalysts used in heterogeneous Fenton or Fenton-like reactions, such as H 2 O 2-Fe 3+ (solid)/nano-zero-valent iron/immobilized iron and electro-Fenton-pyrite. Surface properties of heterogeneous catalysts generally control the efficiency to degrade pollutants. Examples of Fenton reactions are demonstrated to degrade and mineralize a wide range of water pollutants in real industrial wastewaters, such as dyes and phenols. Removal of various antibiotics by homogeneous and heterogeneous Fenton reactions is exemplified.

Advanced Oxidation Processes for the Removal of Antibiotics from Water. An Overview

“…On the contrary, references to works published in the 1970s, 1980s, and 1990s have been reduced to a minimum. This paper follows the path of some previously published reviews dealing with the removal of antibiotics in water by AOPs [35][36][37][38][39][40][41][42][43][44][45][46][47].…”

“…where R represents the organic compound, and P1 and P2 are the formed intermediates and final products of the oxidation. The first reaction of the mechanism is responsible for the formation of hydroxyl radicals [118] It is worth noting that in Reactions (43)- (45), Fe 2+ is regenerated, so that the Fenton process can be regarded as catalytic with respect to iron. Therefore, the reaction of formation of OH radicals can continue to take place as long as there is hydrogen peroxide in the medium.…”

Studies on the Kinetics of Doxazosin Degradation in Simulated Environmental Conditions and Selected Advanced Oxidation Processes

“…The operation of the Fenton system is very complex and not fully known yet. The reaction mechanism involves the generation of hydroxyl radical according to the following reaction) [34]:…”

“…The Fenton reagent with the concentration of 10 −4 mol dm −3 of the components was selected for further testing, resulting in the determination of the kinetic parameters of DOX degradation with good precision. The influence of pH was checked next; it is known that the optimal working pH for the studied process is contained in the range 2-5 [34]. At an excess of hydrogen ions, less reactive positively charged ferrous species are formed [35].…”

Enhanced Visible Light Photocatalytic Activity of TiO2 Nanospheres/SnO2 Quantum Dots Composite for Degradation of 4-Nitrophenol

“…Various methods and techniques such as AOPs, biological methods, physical methods, etc. are developed to remove these pollutants [1][2][3][4][5][6][7][8][9][10][11]. Cost-effectiveness, ecofriendly nature and applicability on large scale for different kind of pollutants are the key factors behind this.…”