Advanced Oxidation Process (original) (raw)
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Fenton chemistry encompasses reactions of hydrogen peroxide in the presence of iron to generate highly reactive species such as the hydroxyl radical and possibly others. In this review, the complex mechanisms of Fenton and Fenton-like reactions and the important factors influencing these reactions, from both a fundamental and practical perspective, in applications to water and soil treatment, are discussed. The review covers modified versions including the photoassisted Fenton reaction, use of chelated iron, electro-Fenton reactions, and Fenton reactions using heterogeneous catalysts. Sections are devoted to nonclassical pathways, by-products, kinetics and process modeling, experimental design methodology, soil and aquifer treatment, use of Fenton in combination with other advanced oxidation processes or biodegradation, economic comparison with other advanced oxidation processes, and case studies.
A review of classic Fenton's peroxidation as an advanced oxidation technique
Hydrogen peroxide (H 2 O 2) is a strong oxidant and its application in the treatment of various inorganic and organic pollutants is well established. Still H 2 O 2 alone is not effective for high concentrations of certain refractory contaminants because of low rates of reaction at reasonable H 2 O 2 concentrations. Improvements can be achieved by using transition metal salts (e.g. iron salts) or ozone and UV-light can activate H 2 O 2 to form hydroxyl radicals, which are strong oxidants. Oxidation processes utilising activation of H 2 O 2 by iron salts, classically referred to as Fenton's reagent is known to be very effective in the destruction of many hazardous organic pollutants in water. The first part of our paper presents a literature review of the various Fenton reagent reactions which constitute the overall kinetic scheme with all possible side reactions. It also sum-marises previous publications on the relationships between the dominant parameters (e.g. [H 2 O 2 ], [Fe 2+ ],. . .). The second part of our review discusses the possibility of improving sludge dewater-ability using Fenton's reagent.
Treatment of organic pollutants by homogeneous and heterogeneous Fenton reaction processes
Environmental Chemistry Letters, 2018
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.
A review on Fenton and improvements to the Fenton process for wastewater treatment
Journal of Environmental Chemical Engineering, 2014
The increase in the disposal of refractory organics demands for newer technologies for the complete mineralization of these wastewaters. Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of such wastewaters and this study presents a general review on such processes developed to decolorize and/or degrade organic pollutants. Fundamentals and main applications of typical methods such as Fenton, electro-Fenton, photo-Fenton, sono-Fenton, sonophoto-Fenton, sono-electro-Fenton and photo-electro-Fenton are discussed. This review also highlights the application of nano-zero valent iron in treating refractory compounds.
Abstract In these years, due to the increasing presence of molecules in industrial waste water from factories and petroleum refineries, the conventional biological methods cannot be used for complete treatment of the effluent therefore the need to newer technologies to degrade these refractory molecules into smaller molecules became very imperative. Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters. Fenton’s oxidation was one of the best known metal catalyzed oxidation reactions of water-miscible organic compounds. The mixture of FeSO4 or any other ferrous complex and H2O2 (Fenton’s reagent) at low enough pH, results in Fe2+ catalytic decomposition of H2O2 and proceeds via a free radical chain process that produces hydroxyl radicals which have extremely high oxidizing ability and could oxidize hard to decompose organic compounds in a short time. This work aims at highlighting Fenton’s oxidation processes operating at ambient conditions viz. photo-catalytic oxidation, Fenton’s chemistry and use of hydrogen peroxide. The pre-oxidation of an extremely polluted pharmaceutical wastewater, Direct Blue 71 (DB71) oil recovery industry wastewater, the fish canning industrial wastewater, Active pharmaceutical intermediates (API) in waste waters by Fenton’s oxidation process to degrade organic pollutants. The work highlights the basics of these individual processes including the reactor design aspects, the optimum parameters such as dosage of ferrous sulfate and hydrogen peroxide, pH and initial concentration of pollutants and a complete overview of the various applications to wastewater treatment by Fenton’s oxidation processes in the recent years. This study presents a general review on the effectiveness of Fenton’s technique for the treatment of semi-aerobic landfill leachate (Treatment with Fenton’s reagent appears to be an appropriate method for oxidizing recalcitrant
Pilot-scale Fenton’s oxidation of organic contaminants in groundwater using autochthonous iron
Journal of Hazardous Materials, 2003
A pilot-scale study was conducted to evaluate Fenton's oxidation with autochthonous iron for treating extracted groundwater contaminated with organic solvents. Based on a previous bench-scale treatability study, a batch reactor pilot-plant system was designed and operated to evaluate the effects of various parameters including pH, iron concentration, hydrogen peroxide dose, and reaction time. Effective system conditions were found to be pH of 3.5, hydrogen peroxide to iron molar ratio of 75/1, and autochthonous iron at an average concentration of 10 mg/l. The data collected demonstrate the effectiveness of Fenton's oxidation using autochthonous iron for treating this contaminated water, with reductions to below method detection limits for many contaminants. This pilot-scale study provided kinetic rate constants for predicting contaminant disappearance, information necessary for designing a full-scale Fenton's oxidation system.
Photo-fenton remediation of wastewaters containing agrochemicals
Brazilian Archives of Biology and Technology, 2005
The photochemical degradation of agrochemicals in aqueous solution by means of advanced oxidation processes (AOPs) was studied. The photo-Fenton process was evaluated in terms of the time evolution of dissolved organic carbon (COD) and chemical oxygen demand (DOC), their total removals, and increase in biodegradability of treated wastewater. Under the experimental conditions studied, the process showed to be superior to other AOPs, at any Fe(II) and H2O2 concentrations. The results pointed towards the use of solar irradiation and low cost commercial application.
Application of Chelating Agents to Enhance Fenton Process in Soil Remediation: A Review
Catalysts, 2021
Persistent organic contaminants affecting soil and groundwater pose a significant threat to ecosystems and human health. Fenton oxidation is an efficient treatment for removing these pollutants in the aqueous phase at acidic pH. However, the in-situ application of this technology for soil remediation (where pHs around neutrality are required) presents important limitations, such as catalyst (iron) availability and oxidant (H2O2) stability. The addition of chelating agents (CAs), forming complexes with Fe and enabling Fenton reactions under these conditions, so-called chelate-modified Fenton process (MF), tries to overcome the challenges identified in conventional Fenton. Despite the growing interest in this technology, there is not yet a critical review compiling the information needed for its real application. The advantages and drawbacks of MF must be clarified, and the recent achievements should be shared with the scientific community. This review provides a general overview of t...
Asian Journal of Chemistry and Pharmaceutical Sciences
Advanced Oxidation Processes (AOPs) have emerged as a promising technology for the treatment of wastewaters containing toxic, recalcitrant organic compounds such as dyes, pesticides etc. This review paper focuses on the Fenton and photo- Fenton technique which is one of the most efficient AOPs developed to decolorize and/or degrade organic pollutants. This oxidation method can produce biodegradable intermediates and mineralize complex organic pollutants effectively and efficiently. In this paper Fenton and photo-Fenton methods are categorised into two broad groups as homogeneous and heterogeneous Fenton and photo-Fenton processes. Applications of fundamental and advanced combined Fenton and photo-Fenton processes are also discussed.