Principles, influencing factors and optimization measures of Fenton oxidation technology

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Fenton oxidation technology is an efficient advanced oxidation treatment (AOPs) process designed to eliminate organic pollutants that are difficult to degrade or toxic in wastewater. Its core technology is based on the chemical reaction of Fenton's reagents (Fe² + and H₂O₂), which produces hydroxyl radicals (•OH) with extremely high oxidizing power, thus effectively oxidizing and breaking down organic matter in wastewater. The following is a detailed description of the principles, influencing factors and optimization strategies of Fenton oxidation technology.

First, technical principles

1. Basic reactions
- Fe squared ⁺ catalytic decomposition of H ₂ O ₂ : in Fe squared ⁺ under the catalysis of H ₂ O ₂ decomposition for, OH, OH ⁻ and Fe after ⁺. •OH's strong oxidation allows it to react quickly with most organic pollutants, mineralizing it into harmless substances such as water and carbon dioxide.
- Fe³ + Recycling cycle with H₂O₂ : Fe³ + + reacts with H₂O₂ and OH⁻ to produce Fe² + again, achieving the recycling of a catalyst.

2. Auxiliary response
- Fe³ + Direct oxidation of organic matter: Fe³ + also possesses a certain amount of oxidative power in itself and reacts directly with some organic pollutants.
- Oxidation of complexes formed by Fe² + /Fe³ + with organics: Fe² + and Fe³ + form complexes with certain organics which are more prone to oxidation in the Fenton system.

2. Influencing factors

1. pH value: The best effect of Fenton reaction is between pH 2.5 and 4. Acidic environments favour the stable presence of Fe² +, the breakdown of H₂O₂ and the production of •OH.
2. The ratio of Fe² + to H₂O₂ : An appropriate ratio ensures that Fe² + effectively catalyzes the breakdown of H₂O₂ and that Fe³ + effectively reproduces into Fe² +.
3. Reaction temperature: Rising temperature can speed up the reaction rate, but too high temperature will accelerate the ineffective decomposition of H₂O₂.
4. Reaction time: Sufficient reaction time can ensure the full degradation of pollutants, but too long time will increase the cost.
5. Wastewater composition: Other substances in wastewater, such as buffer substances, chelating agents, organic properties and anions, may affect the efficiency of Fenton reaction.

Third, optimization measures

1. Catalyst optimization
- Select a suitable iron salt or iron-supported solid catalyst to improve the dispersion and stability of the catalyst.
- Precise control of the concentration of Fe² + and maintenance of an optimal Fe² + /H₂O₂ ratio.
- Promote the reduction of Fe³ + + to Fe² + by means of electrochemical and photochemical methods and improve the recycling efficiency of catalysts.

2. Oxidant optimization
- Optimize the dosage of H₂O₂, such as batch or continuous addition, to maintain a stable H₂O₂ concentration.
- Use stabilizers to slow down the decomposition of H₂O₂ and improve its effective concentration in practical applications.

3. Optimization of reaction conditions
- Adjust the pH value of wastewater by adding acid or base to maintain the optimal pH range of Fenton reaction.
- Adjust reaction temperature and time according to wastewater characteristics and treatment requirements.

By taking the above optimization measures, the treatment efficiency of Fenton oxidation technology can be further improved, the treatment cost can be reduced, and the problems that may be encountered in practical applications can be solved.

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