CN117303552A - Method for degrading organic pollutants in water by permanganate-persulfate synergistic oxidation - Google Patents

Abstract

The invention belongs to the technical field of water treatment, and particularly relates to a method for degrading organic pollutants in water by synergistic oxidation of permanganate and persulfate. For the prior persulfate oxidation, the prior persulfate oxidation generally adopts the reducing Fe ²⁺ The invention provides a method for degrading organic pollutants in water by synergistic oxidation of permanganate and persulfate, which comprises the following steps of: firstly adding permanganate into the organic wastewater to be treated, controlling the reaction time, then adding persulfate into the reaction system, mixing, and continuing the reaction to finally finish the oxidative degradation of organic pollutants in the wastewater. Compared with the oxidation of permanganate and persulfate alone, the method improves the mineralization rate of the organic matters by more than 1 time, has simple and convenient operation method, has wide application range to the pH of the wastewater, and is large-scale and high in concentrationHas application prospect in the organic wastewater treatment engineering.

Description

Method for synergistic oxidative degradation of organic pollutants in water by permanganate-persulfate

Technical field

The invention belongs to the technical field of water treatment, and particularly relates to a method for synergistic oxidation and degradation of organic pollutants in water by permanganate-persulfate.

Background technique

Wastewater discharged from organic chemicals, pharmaceutical factories, coking chemicals and other industries contains a large amount of organic pollutants such as benzene series, antibiotics and polycyclic aromatic hydrocarbons. When these pollutants enter the water body, they will seriously affect the health of residents and have a negative impact on the ecology. System poses a threat. For example, the International Health Organization classifies benzene as a strong carcinogen. Benzene series substances have varying degrees of toxicity to the human body and aquatic organisms, and can cause strong harm to the human blood, nervous, and reproductive systems. my country is a big country in the production and use of antibiotics. The abuse of antibiotics will cause some adverse effects on humans through the role of the food chain. It may even induce microorganisms to produce drug resistance and resistance genes (ARG), destroying the imbalance of the ecosystem. Antibiotics have been recognized internationally as Listed as one of the new pollutants. Polycyclic aromatic hydrocarbons are strong carcinogens that can cause cancer through human exposure. Among more than 500 known carcinogens, more than 200 are related to polycyclic aromatic hydrocarbons. Therefore, the effective treatment of the above-mentioned organic pollutants in wastewater is of great significance to ensuring the health of our people, social stability and the construction of ecological civilization.

The treatment of benzene series, antibiotics and polycyclic aromatic hydrocarbons in water mainly includes adsorption method, membrane method and chemical oxidation method. Among them, persulfate, as a new type of chemical oxidant, can produce strong oxidizing sulfate radicals and quickly mineralize organic pollutants. It has the characteristics of strong oxidation ability, fast reaction speed, wide application range and no secondary pollution. , has high treatment efficiency for organic substances such as drugs, pesticides, phenols and polycyclic aromatic hydrocarbons, and has broad application prospects in organic wastewater treatment. However, the persulfate oxidation reaction usually requires transition metal ions (Mn ²⁺ , Fe ²⁺ , cu ²⁺ , Ag ^{+ ,} etc.) for activation, and currently reducing Fe ²⁺ is mostly used as the activator. However, under ambient temperature conditions, on the one hand, the free radicals generated can oxidize Fe ²⁺ to Fe ³⁺ , resulting in the loss of persulfate and Fe ²⁺ . At the same time, Fe ²⁺ and Fe ³⁺ can react in neutral to alkaline conditions. Precipitate under the conditions, causing the activator to fail; on the other hand, the introduction of iron ions will cause the accumulation of iron sludge, and the pH applicable range is small.

At present, electroactivation technology is also used to activate persulfate to generate strong oxidizing sulfate radicals to attack difficult-to-degrade pollutants. For example, patent CN 113023843 A discloses a method for cathode and anode synergistic activation of permanganate-persulfate to degrade organic matter in water. , but this patent adds permanganate-persulfate to the reaction system at the same time and uses electric activation technology. The time is difficult to control. At the same time, the concentration of pollutant treatment is low, so the system efficiency is not high and is not conducive to cost reduction. Therefore, there is an urgent need for treatment. This persulfate advanced oxidation technology is further improved and optimized.

Contents of the invention

In view of the existing advanced oxidation of persulfate, the reducing Fe ²⁺ activator is often used, which is prone to failure, requires high environmental conditions for activation, and produces secondary pollution from iron sludge, or the use of electroactivation technology is complex in operation, high in cost, and low in system efficiency. Problem, the present invention provides a method for permanganate-persulfate synergistic oxidative degradation of organic pollutants in water.

The technical solutions to achieve the above objectives are as follows:

The method of permanganate-persulfate synergistic oxidative degradation of organic pollutants in water includes the following steps:

First add permanganate to the organic wastewater to be treated, control the reaction time, then add persulfate to the reaction system, mix and continue the reaction, and finally complete the oxidative degradation of organic pollutants in the wastewater.

Wherein, the initial concentration of permanganate is 1-100mM.

Wherein, the initial concentration of persulfate is 2 to 10 times the concentration of permanganate.

Wherein, the permanganate is selected from at least one of potassium permanganate or sodium permanganate.

Wherein, the persulfate is selected from at least one of sodium persulfate or potassium persulfate.

Wherein, the pollutants in the organic wastewater are mainly at least one of benzene series, antibiotics or polycyclic aromatic hydrocarbons.

Wherein, after the permanganate is added, the reaction time needs to be controlled to be 0.5 to 2.0 h at room temperature. Preferably, the reaction time after adding permanganate is 1.0 h.

Wherein, the reaction time after adding persulfate is 3.0 to 5.0 hours of mixing reaction at room temperature. Preferably, the reaction time after adding persulfate is 5.0 h.

Wherein, the dosage form of the permanganate or persulfate is direct dosage in solid form or dosage of its aqueous solution.

Beneficial effects:

1. The present invention utilizes permanganate to oxidize organic matter to produce active manganese species such as Mn ²⁺ , Mn(IV) and Mn(VI), and catalytically activates persulfate to generate sulfate radicals to achieve secondary oxidation of organic matter. Without adding other catalysts, the mineralization rate of organic pollutants is more than doubled compared with permanganate or persulfate oxidation alone, and the mineralization rate of typical organic matter is also higher than that of Fe-activated persulfate oxidation.

2. Since permanganate itself is a stable and strong oxidant, it can oxidatively degrade organic matter in a wide pH range and has strong adaptability to wastewater of different pH. Persulfate activation produces sulfate radical oxidation ability It is strong and has a good effect on the mineralization and degradation of refractory organic pollutants. At the same time, the reaction only requires the addition of two reagents in sequence, without the need for other external forces, such as power supply, so the operation is simple and convenient, and the cost is low.

3. The pharmaceutical agent used in the present invention is easy to purchase in the market, low in price, environmentally friendly, and easy to store and transport. Therefore, it is suitable for application in large-scale high-concentration organic wastewater treatment projects.

Description of drawings

Figure 1 is a comparison chart of the mineralization rate of organic matter under the action of different oxidants in Example 1 of the present invention;

Figure 2 is a comparison chart of the mineralization rate of organic matter under different adding methods and reaction times of oxidants in Example 2 of the present invention.

Detailed ways

The invention discloses a method for permanganate-persulfate synergistic oxidative degradation of organic pollutants in water. The method first mixes organic wastewater to be treated with permanganate of a certain concentration, and controls the oxidation reaction time; and then Persulfate is added to the above reaction system for further reaction to oxidatively degrade organic pollutants in the water.

The reaction principle is as follows:

In this system, permanganate, such as KMnO ₄ and NaMnO ₄ , is itself a stable and strong oxidant, which can oxidatively degrade organic matter in a wide pH range and produce Mn ²⁺ , Mn(IV) and Mn(VI). ) and other active manganese species, as shown in formulas (1) to (3). Mn ²⁺ is a transition metal ion, and MnO ₂ and Mn(IV) themselves have both oxidizing and catalytic properties, so they can continue to catalytically activate persulfate to generate sulfate radicals, and perform a second oxidation of organic matter in the system , this can replace reducing Fe ²⁺ , which not only avoids the easy oxidation of Fe ²⁺ but also enhances the oxidation ability. Achieve synergistic oxidation of permanganate and persulfate.

MnO ₄ ^- +8H ⁺ +5e ^- →Mn ²⁺ +4H ₂ O (1)

MnO ₄ ^- +2H ₂ O+3e ^- →MnO ₂ (s)+4OH- (2)

MnO ₄ ^- +e ^- →MnO ₄ ^2- (3)

The method of the present invention makes full use of the oxidizing properties of permanganate. After first degrading some organic pollutants, the generated compounds containing Mn ²⁺ and MnO ₂ can be used as catalysts to replace Fe to activate persulfate to generate strong oxidizing properties such as free radicals and singlet oxygen. substances, further oxidizing and degrading the remaining pollutants, greatly improving the mineralization treatment rate of organic matter.

In a preferred embodiment of the present invention, the initial concentration of permanganate is 1 to 100 mM.

In a preferred embodiment of the present invention, the initial concentration of persulfate is 2 to 10 times the concentration of permanganate.

In a preferred embodiment of the present invention, the permanganate is at least one of potassium permanganate or sodium permanganate.

In a preferred embodiment of the present invention, the persulfate is at least one of sodium persulfate or potassium persulfate.

In a preferred embodiment of the present invention, the organic pollutants in the water mainly contain at least one of benzene series, antibiotics and polycyclic aromatic hydrocarbons.

In a preferred embodiment of the present invention, permanganate is first added to the organic wastewater to be treated, and the reaction time is controlled to be 0.5 to 2.0 h at room temperature, and then persulfate is added. . Preferably, the reaction time after adding permanganate is 1.0 h.

In a preferred embodiment of the present invention, persulfate is added to the reaction system, and the reaction is continued for 3.0 to 5.0 hours at room temperature. Preferably, the reaction time after adding persulfate is 5.0 h.

In a preferred embodiment of the present invention, the permanganate or persulfate can be directly added as a solid or its aqueous solution.

Compared with permanganate and persulfate oxidation alone, the technical solution of the present invention can more than double the mineralization rate of organic matter; the mineralization rate of typical organic matter is also higher than the Fe-activated persulfate oxidation reaction, while avoiding reducing Fe When used as a catalyst, it is easy to oxidize, causing the agent to be difficult to transport and store. No Fe sludge is produced; the two agents used are cheap, easy to obtain, environmentally friendly, and easy to operate. They have a wide adaptability to the pH of wastewater and can be used in large-scale and high-concentration applications. It has application prospects in organic wastewater treatment projects.

The solutions of the present invention will be explained below with reference to examples. Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. If specific techniques or conditions are not specified in the examples, the techniques or conditions described in literature in the field or product instructions will be followed. If the manufacturer of the reagents or instruments used is not indicated, they are all conventional products that can be purchased commercially.

Example 1

Phenolic pollutants are a type of refractory pollutants that widely exist in the environment, posing a huge threat to water resources security and human health. 2-Chlorophenol is the most representative phenolic pollutant, which is highly toxic and biological. It is difficult to degrade, so 2-chlorophenol is used in the following examples.

Take four 40mL brown glass bottles as reactors, add 20mL of 2-chlorophenol respectively, and make the initial concentration of 2-chlorophenol in the reaction system 250mg/L, and then add 5mL of a certain concentration to two of the reactors. KMnO ₄ or Na ₂ S ₂ O ₈ solution. After mixing, the initial concentration of KMnO ₄ or Na ₂ S ₂ O ₈ is 20 mmol/L. Place the reactor at room temperature (25°C) and shake in a 120 rpm shaker for 6 hours. ; First add 5mL of KMnO ₄ to the third reactor. After mixing, the initial concentration of KMnO ₄ is 4mmol/L. Place the reactor at room temperature (25°C) and shake in a shaker at 120 rpm for 1 hour. After the reaction, add 1 mol /L Na ₂ S ₂ O ₈ solution. The initial concentration of Na ₂ S ₂ O ₈ after mixing is 20 mmol/L. Place the reactor at room temperature (25°C) and shake in a 120 rpm shaker for 5 hours; in the fourth step Add 0.05g of nano zero-valent iron catalyst (nZIV/BC) and 5mL of Na ₂ S ₂ O ₈ into each reactor. After mixing, the concentration is 20mmol/L. Place the reactor at room temperature (25°C) and shake at 120 rpm. React with medium shaking for 6 hours. The total reaction time of the four reactors is 6 hours. After the reaction is completed, 10 mL of the solution is drawn, filtered with a 0.22 μm PTFE filter, and the TOC is measured after the ultrapure water is diluted to volume. Each condition was repeated twice and averaged. The results are shown in Figure 1.

As shown in Figure 1, after 6 hours of oxidation by KMnO ₄ or Na ₂ S ₂ O ₈ alone, the mineralization rates of ₂ - _chlorophenol in water were 31.58% and 5.32% _respectively . The mineralization rate of chlorophenol reaches 67.64%, while the mineralization rate of 2-chlorophenol reached 69.08% by KMnO ₄ -Na ₂ S ₂ O ₈ collaborative oxidation treatment, which is higher than the ore oxidized by KMnO ₄ or Na ₂ S ₂ O ₈ alone. The mineralization rate is more than doubled, and the mineralization rate is also higher than that of iron-catalyzed Na ₂ S ₂ O ₈ oxidation.

Example 2

Considering that both KMnO ₄ and Na ₂ S ₂ O ₈ are oxidation reactions, the effects of the adding methods of KMnO ₄ and Na ₂ S ₂ O ₈ on the mineralization rate of 2-chlorophenol solution were compared. Take five 40 mL brown glass bottles as reactors, add 20 mL of 2-chlorophenol respectively, and make the initial concentration of 2-chlorophenol in the reaction system 250 mg/L. The first reactor (control) did not add any KMnO ₄ and Na ₂ S ₂ O ₈ as a control. The second reactor (T1) added KMnO ₄ and Na ₂ S ₂ O ₈ at the same time, and mixed the KMnO The initial concentrations of ₄ and Na ₂ S ₂ O ₈ are 4mmol/L and 20mmol/L respectively. Place the reactor at room temperature (25°C) and shake in a 120rpm shaker for 6h; in the third reactor (T2) First add 5 mL of KMnO ₄ to the mixture. After mixing, the initial concentration of KMnO ₄ is 4 mmol/L. Place the reactor at room temperature (25°C) and shake in a 120 rpm shaker for 1 hour. Then add 1 mol/L of Na ₂ S ₂ O ₈ solution, the initial concentration of Na ₂ S ₂ O ₈ after mixing is 20 mmol/L. Place the reactor at room temperature (25°C) and shake in a shaker at 120 rpm for 5 hours. First add 5 mL of KMnO ₄ to the fourth reactor (T3). After mixing, the initial concentration of KMnO ₄ is 4 mmol/L. Place the reactor at room temperature (25°C) and shake in a shaker at 120 rpm for 3 hours. After the reaction, Add 1 mol/L Na ₂ S ₂ O ₈ solution. After mixing, the initial concentration of Na ₂ S ₂ O ₈ is 20 mmol/L. Place the reactor at room temperature (25°C) and shake in a 120 rpm shaker for 3 hours. First add 5 mL of KMnO ₄ to the fifth reactor (T4). After mixing, the initial concentration of KMnO ₄ is 4 mmol/L. Place the reactor at room temperature (25°C) and shake in a shaker at 120 rpm for 5 hours. After the reaction, Add 1 mol/L Na ₂ S ₂ O ₈ solution. After mixing, the initial concentration of Na ₂ S ₂ O ₈ is 20 mmol/L. Place the reactor at room temperature (25°C) and shake in a shaker at 120 rpm for 1 hour. The total reaction time of the five reactors is 6 hours. After the reaction is completed, 10 mL of the solution is drawn, filtered with a 0.22 μm PTFE filter, and the TOC is measured after the ultrapure water is diluted to volume. Each condition was repeated twice and the average value was taken. The results are shown in Figure 2. As shown in Figure 2, after reaction group T1 added KMnO ₄ and Na ₂ S ₂ O ₈ at the same time for 6 hours of oxidation, the mineralization rate of 2-chlorophenol in water was 59.96%, while reaction group T2 added KMnO ₄ first and reacted for 1 hour. , then adding Na ₂ S ₂ O ₈ for collaborative oxidation treatment for 5 hours, the mineralization rate of 2-chlorophenol reached 69.08%, which was significantly higher than the mineralization rate of simultaneous oxidation; reaction group T3 also added KMnO ₄ first, but the reaction lasted for 3 hours, and then The mineralization rate of 2-chlorophenol can only reach 63.41% after adding Na ₂ S ₂ O ₈ for collaborative oxidation treatment for 3 hours; similarly, although reaction group T4 also added KMnO ₄ first, it reacted for 5 hours before adding Na ₂ S ₂ O The mineralization rate of 2-chlorophenol can only reach 57.25% after 1 hour of collaborative oxidation treatment by ₈ animals. This shows that the addition order and reaction time of the two oxidants have an important impact on the overall degradation efficiency. The main reason is that the added KMnO ₄ requires a certain reaction time to form low-valent Mn, and then catalytically activate Na ₂ S ₂ O ₈ advanced oxidation reaction. However, the reaction time of adding KMnO ₄ first is too long, which is not conducive to the subsequent Na ₂ S ₂ O ₈ collaborative oxidation treatment efficiency, so an optimal time range is required.

Claims (9)

1. A method for permanganate-persulfate synergistic oxidative degradation of organic pollutants in water, which is characterized by: including the following steps: First add permanganate to the organic wastewater to be treated, control the reaction time, then add persulfate to the reaction system, mix and continue the reaction, and finally complete the oxidative degradation of organic pollutants in the wastewater. 2. The method of permanganate-persulfate collaborative oxidative degradation of organic pollutants in water according to claim 1, characterized in that: the initial concentration of permanganate is 1 to 100mM. 3. The method for permanganate-persulfate synergistic oxidation and degradation of organic pollutants in water according to claim 1, characterized in that: the initial concentration of persulfate is the permanganate dosage concentration. 2 to 10 times. 4. The method for permanganate-persulfate synergistic oxidative degradation of organic pollutants in water according to claim 1, characterized in that: the permanganate is selected from at least potassium permanganate or sodium permanganate. A sort of. 5. The method of permanganate-persulfate collaborative oxidative degradation of organic pollutants in water according to claim 1, characterized in that: the persulfate is selected from at least one of sodium persulfate or potassium persulfate. 6. The method of permanganate-persulfate synergistic oxidation and degradation of organic pollutants in water according to claim 1, characterized in that: the pollutants in the organic wastewater are mainly benzene series, antibiotics or polycyclic aromatic hydrocarbons. At least one. 7. The method of permanganate-persulfate collaborative oxidation and degradation of organic pollutants in water according to claim 1, characterized in that: after adding permanganate, the reaction time at room temperature needs to be controlled to 0.5 ~2.0h; preferably, the reaction time of adding permanganate is 1.0h. 8. The method of permanganate-persulfate synergistic oxidation and degradation of organic pollutants in water according to claim 1, characterized in that: the reaction time after adding persulfate is 3.0 to 5.0 in a mixed reaction at room temperature. h; Preferably, the reaction time after adding persulfate is 5.0h. 9. The method for permanganate-persulfate synergistic oxidative degradation of organic pollutants in water according to claim 1, characterized in that: the permanganate or persulfate dosage form is directly added in solid form. Add or add its aqueous solution.