It can be used as standalone and in combination with other treatment processes. Fenton reaction can be carried out using homogeneous or heterogeneous catalyst. Traditionally, Fenton reaction employs iron salts and hydrogen peroxide under acidic conditions for generating hydroxyl radicals that are highly oxidizing.
Full Answer
What is Fentons reagent and how it works?
Hydrogen peroxide and Ferrous ion combined together is popularly known as Fentons Reagent. This reagent is capable of treating a whole wide range of Wastewater including phenols, Formaldehyde, BTEX and complex waste of pesticide, speciality chemicals, dyes etc.
What is Fenton process in wastewater treatment?
Fenton process: Fenton process is encompass hydrogen peroxide (H2O2)) with iron ions reaction to form active oxygen spec ies that. oxidize organic or inorganic compounds [34]. In the recent past, Fenton reaction was efficiently utilized in wastewater treatm ent pro cess for the removal of many.
Is it appropriate to discuss Fenton chemistry rather than Fenton reaction?
Therefore, it may be appropriate to broadly discuss Fenton chemistry rather than a specific Fenton reaction . In the electro-Fenton process, hydrogen peroxide is produced in situ from the electrochemical reduction of oxygen.
What does Fenton reagent do?
Fenton's reagent is a solution of hydrogen peroxide and the ferrous ion. Generally, Fenton's reagent is a solution of ferrous sulfate in hydrogen peroxide. In this reagent, the ferrous ion acts as a catalyst and promotes the formation of free radicals.
What is produced in Fenton reaction?
The Fenton reaction describes the formation of hydroxide (OH−) and hydroxyl radical by a reaction between Iron (II) (Fe2+) and hydrogen peroxide (H2O2) [33], Haber–Weiss reaction is where hydroxyl and hydroxide ions are generated from the reaction of H2O2 and superoxide ion ( O 2 • − ) catalyzed by iron [34].
What is Fenton treatment?
Fenton is an effective advanced treatment process. The hydroxyl radical (·OH) can be generated from the reaction between aqueous ferrous ions and hydrogen peroxide (H2O2), and it can destroy refractory and toxic organic pollutants in wastewater [2].
What is Fenton degradation?
In Fenton's reaction, the ferrous and/or ferric cation decomposes catalytically hydrogen peroxide to generate powerful oxidizing agents, capable of degrading a number of organic and inorganic substances.
What is Fenton like catalyst?
A key characteristic of the Fenton-like process carried out by iron-based catalysts is their ability to degrade wide range of organics (Zhou et al. 2008). Further, iron-based catalysts afford high reaction rates in terms of organic degradation, but rate of mineralization is far slower due to two possible reasons.
What is photo Fenton reaction?
The photo-Fenton reaction, oxidation of photoproduced ferrous iron by hydrogen peroxide, produces reactive oxidants that may be important to degradation of biologically and chemically recalcitrant organic compounds in surface waters at circum-neutral pH.
How did Fenton reaction of iron occur?
The decomposition of hydrogen peroxide in the presence of iron(II) (Fenton reaction) with formation of hydroxyl radical and hydroxyl anion. The addition of hydroxyl anion onto iron(III) activated nitrone with formation of corresponding salt of hydroxylamine followed by its decomposition into nitroxide and iron(II).
What happens when lactic acid is treated with Fenton's reagent?
Solution : It gives pyruvic acid.
What is oxidation in water treatment?
Advanced oxidation processes (abbreviation: AOPs), in a broad sense, refers to a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and waste water by oxidation through reactions with hydroxyl radicals (·OH).
How does pH affect Fenton reaction?
The acidic pH regime is favourable for Fenton oxidation due to the presence of iron in the soluble state. Under alkaline conditions, iron precipitates as Fe(OH) 3 , thus affecting the availability of Fe to react with H 2 O 2 to form reactive oxygen species (ROS) (Jung et al., 2009; Zhang et al., 2019).
What is Fenton's reagent?
Fenton's reagent is a solution of hydrogen peroxide (H 2 O 2) with ferrous iron (typically iron (II) sulfate, FeSO 4) as a catalyst that is used to oxidize contaminants or waste waters. Fenton's reagent can be used to destroy organic compounds such as trichloroethylene (TCE) and tetrachloroethylene (perchloroethylene, PCE).
What is the oxidation of iron?
Overview. Iron (II) is oxidized by hydrogen peroxide to iron ( III), forming a hydroxyl radical and a hydroxide ion in the process. Iron (III) is then reduced back to iron (II) by another molecule of hydrogen peroxide, forming a hydroperoxyl radical and a proton.
How does pH affect reaction rate?
pH affects the reaction rate due to a variety of different reasons. At a low pH, complexation of Fe 2+ also occurs, leading to lower availability of Fe 2+ to form reactive oxidative species (OH•). Lower pH also results in the scavenging of • OH by excess H +, hence reducing its reaction rate.
Is hydroxyl an oxidant?
For example, the hydroxyl is a powerful, non-selective oxidant. Oxidation of an organic compound by Fenton's reagent is rapid and exothermic and results in the oxidation of contaminants to primarily carbon dioxide and water. Reaction ( 1) was suggested by Haber and Weiss in the 1930s as part of what would become the Haber–Weiss reaction.
What is advanced oxidation process?
Advance Oxidation Process (AOPS) since late 1980s have become one important area for research and application in area of wastewater treatment dealing with the disposal of refractory compounds. AOPs are the process in which the impurities of effluent are removed by generating hydroxyl radical. There are different methods to generate hydroxyl radical. The present review paper explains the concept of Advanced Oxidation Process through most common AOP- Fenton process.
What is the reaction rate of hydrogen peroxide with ferrous ion?
The reaction rate of Hydrogen peroxide with ferrous ion is very high . In presence of excess Hydrogen Peroxide, Fe2+ oxidises to Fe3+ in just few seconds to minute decomposing hydrogen peroxide into Hydroxyl radicals. This is the reaction mechanism of Fenton process.
When was Fenton's reaction discovered?
Fenton discovered the Fenton reaction in 1894, and he reported that H 2 O 2 could be activated by ferrous (Fe 2+) salts to oxidize tartaric acid. However, its application as an oxidizing process for destroying toxic organics was achieved until the late 1960s [ 3 ].
What is a Fenton?
Fenton is an effective advanced treatment process. The hydroxyl radical (·OH) can be generated from the reaction between aqueous ferrous ions and hydrogen peroxide (H 2 O 2 ), and it can destroy refractory and toxic organic pollutants in wastewater [ 2 ].
What is Fenton wastewater treatment?
Fenton is considered to be one of the most effective advanced treatment processes in the removal of many hazardous organic pollutants from refractory/toxic wastewater.
Why is ferric sludge a secondary pollution?
The discharge of ferric sludge easily causes secondary pollution because of residual organics adsorbed and accumulated in ferric sludge from treated wastewater. The disadvantage is, therefore, the main obstacle limiting the development and application of the Fenton process [ 61 ].
What is Fenton's reagent?
Fenton’s reagent is a term that is used to denote a solution of hydrogen peroxide that contains the ferrous ion (the Fe 2+ cation in which iron exhibits an oxidation state of +2). The ferrous ion works as a catalyst and promotes the oxidation of contaminants and wastewater.
What is the first stage of Fenton's reaction?
The first stage of Fenton’s reaction (which involves the oxidation of ferrous ions with hydrogen peroxide) forms the basis for the Haber-Weiss reaction, which is a named reaction that generates hydroxyl radicals from superoxide and hydrogen peroxide.
What is the effect of ferric ions on hydrogen peroxide?
Thus, the presence of ferric ions in the hydrogen peroxide solution facilitates the disproportionation of the H 2 O 2 molecules, resulting in the formation of highly toxic free radical species such as the hydroxyl free radical.
How is hydrogen peroxide converted into hydroxyl radical?
Fenton’s reaction is a named reaction in which hydrogen peroxide is converted into a hydroxyl free radical via a catalytic process. The hydrogen peroxide reactant is usually formed by the mitochondrial oxidative respiration. It is important to note that the hydroxyl free radical formed during Fenton’s reaction is highly toxic ...
Why does Fenton's reaction occur so quickly?
Under acidic conditions, Fenton’s reaction proceeds at a very rapid rate because of the increased solubility of ferric ions in acidic media. However, under alkaline conditions, the reaction rate of Fenton’s reaction slows down. This can be explained by the formation of ferric hydroxide (which precipitates out of the solution).
How does ferrous ion work?
The ferrous ion works as a catalyst and promotes the oxidation of contaminants and wastewater. It can be noted that Fenton’s reagent is typically prepared by dissolving iron (II) sulfate (FeSO 4) in hydrogen peroxide.
Why does Fenton's reaction rate increase in acidic media?
Since ferric ions are more soluble in acidic media, the reaction rate of Fenton’s reaction increases in acidic media. Under basic or alkaline media, the reaction rate slows down due to the formation of ferric hydroxide.
What is Fenton's oxidation process?
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 recalcitrantcompounds from landfill leachate), coking wastewater, drinking water networks contaminated with chlorfenvinphos (CFVP), organic pollutants in the textile effluent, pharmaceutical wastewater and agro-industrial wastewaters.
What is pharmaceutical wastewater?
Pharmaceutical Industry wastewater (PIWW) is the product of the drug and formulation development process. And its safe disposal upon treatment is essential. There have been very few studies that reflect on nature of effluents from the Pharmaceutical industries. To select successful and efficacious process of treatment, it is critical to know the characteristics and components of the influent water. Hence, this review aims at comprehensively analysing the characteristics of the pharmaceutical wastewater to provide a better insight on the preferable choices of treatment. Several studies have been carried out on various treatment methods. This paper compares these methods, namely- Physicochemical, Advanced Oxidation and Bioremediation, in which bioremediation emerges as the most sustainable and economically viable option. Additionally, the scope of this paper extends to discuss the various types of bioremediation, their applications and drawbacks in context of industrial wastewater treatment aimed at decreasing the ecotoxicological effects of pharmaceutical wastewater.
What is the treatment of petroleum wastewater?
The treatment of this wastewater can be carried out by physical, chemical and biological treatment processes. Treatment of petroleum wastewater has two stages, firstly, pre-treatment stage to reduce grease, oil and suspended materials. Secondly, an advanced treatment stage to degrade and decrease the pollutants to acceptable discharge values. Most studies are focused on degradation of some pollutants found in the petroleum wastewater such as organic materials, phenols, sulphides and ammonia.
What is the purpose of dyes in wastewater?
The discharge of dyes, specifically synthetic dyes, in wastewater represents a serious environmental problem and causes public health concerns . The implementation of regulations for wastewater discharge has forced research towards either the development of new processes or the improvement of available techniques to attain efficient degradation of dyes. Catalytic oxidation is one of the advanced oxidation processes (AOPs), based on the active radicals produced during the reaction in the presence of a catalyst. This paper reviews the problems of dyes and hydroxyl radical-based oxidation processes, including Fenton’s process, non-iron metal catalysts, and the application of thin metal catalyst-coated tubular reactors in detail. In addition, the sulfate radical-based catalytic oxidation technique has also been described. This study also includes the effects of various operating parameters such as pH, temperature, the concentration of the oxidant, the initial concentration of dyes, and reaction time on the catalytic decomposition of dyes. Moreover, this paper analyzes the recent studies on catalytic oxidation processes. From the present study, it can be concluded that catalytic oxidation processes are very active and environmentally friendly methods for dye removal.
Is Fenton a solid or heterogeneous process?
Heterogeneous Fenton processes with solid catalysts have gained much attention for water and wastewater treatment in recent years. In the field of solid catalysts, zero valent iron (ZVI) is among the most applicable due to its stability, activity, pollutant degradation properties and environmental friendliness. The main limitation in the use of ZVI in heterogene ous Fenton systems is due to its deactivation in neutral and alkaline conditions, and Fenton-like processes have been developed to overcome this difficulty. In this review, the effect of solution pH on the ZVI-Fenton performance is discussed. In addition, the pH trend of ZVI efficiency towards contaminants removal is also considered in oxic solutions (i.e., in the presence of dissolved O2 but without H2O2), as well as in magnetic-field assisted Fenton, sono-Fenton, photo-Fenton and microwave-Fenton processes at different pH values. The comparison of the effect of pH on ZVI performance, taking into account both heterogeneous Fenton and different Fenton-like processes, can guide future studies for developing ZVI applications in water and wastewater treatment.