The Fenton reaction was discovered by chemist Fenton HJ. It is an inorganic chemical reaction. This process is a mixed solution of hydrogen peroxide (H2O2) and divalent iron ions Fe2+, which oxidizes known organic compounds such as carboxylic acids, alcohols, and esters into inorganic states. This reaction is mainly used to oxidize organic compounds that are difficult to degrade in wastewater. It is applied to oily wastewater, coking wastewater, printing and dyeing wastewater, pharmaceutical and other chemical wastewaters with its ultra-high oxidation ability. There are many factors that affect the Fenton reaction. Being able to debug the best oxidation scheme can not only enhance the wastewater treatment effect, but also save costs and improve efficiency. Organic compounds that are difficult to degrade can be degraded into small molecules through the Fenton reaction, and small molecules can be oxidized into carbon dioxide and water. The iron sulfate generated by the Fenton reaction is a trivalent iron ion with a certain flocculation and precipitation effect.
In the process of pharmaceutical and chemical wastewater treatment, Fenton reaction equipment is often used. The factors that affect its reaction effect include: hydrogen peroxide dosage, Fe2+ concentration, pH value, reaction time and temperature.
1. Temperature factor
During the Fenton reaction, within the range of 20-40 degrees Celsius, the higher the temperature, the faster the reaction rate. When the forward generation rate of hydroxide ions increases, the reaction with organic matter can be promoted. When the temperature exceeds a certain value, the decomposition rate of hydrogen peroxide will accelerate.
2. pH value
In an acidic wastewater environment, the Fenton reagent will have a very strong oxidizing ability. As the pH value increases, the catalytic ability of the Fenton reaction will decrease significantly, and the precipitation effect will also weaken. If the trivalent iron ions in the solution cannot be restored to divalent iron ions, the catalytic reaction will be reduced or hindered. If the pH is between 2-5, the catalytic effect of the Fenton reaction will be greatly improved, and the rate of degradation of organic matter will also be very fast. In the specific wastewater treatment process, to adjust the pH to the optimal value, other influencing factors need to be considered.
3. The amount of H2O2 and catalyst input
In the process of pharmaceutical and chemical wastewater treatment, the amount of material reagents put into the Fenton reactor needs to be based on process requirements, which can save costs and achieve better results. Chemical catalytic reaction is a dynamic balance. When the feed reaches a certain level, continuing to feed will not have a significant effect.
Fenton reaction can be used flexibly in wastewater treatment process. It is usually used in conjunction with related processes, such as micro-electrolysis. Because pharmaceutical chemical wastewater has the characteristics of heavy chromaticity, high salt content, complex composition, and high concentration of organic matter, pretreatment of wastewater is an essential process. Most sewage treatment uses Fenton and related derivatives to achieve twice the result with half the effort. Wastewater treatment is sometimes not difficult, but the difficulty lies in how to effectively control costs, improve efficiency, and avoid secondary pollution.
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