CN108059229A - A kind of method of iron carbon activation persulfate processing high-concentration hardly-degradable alkaline waste liquor - Google Patents

Abstract

The invention relates to a method for treating high-concentration refractory alkaline waste liquid with iron-carbon activated persulfate: adding a certain amount of zero-valent iron ( Fe ⁰ ), activated carbon (AC) and persulfate (PS), stir evenly, and react for 2-3 hours under the condition that the initial pH is alkaline, the pollutants can be oxidized and degraded. The present invention adds zero-valent iron and activated carbon to the alkaline waste liquid to synergistically activate the oxidant to generate sulfate radicals and hydroxyl radicals to oxidize pollutants, thereby degrading the alkaline waste liquid; compared with the traditional Fenton oxidation technology, it has more advantages The wide pH range saves the step of adding acid and neutralizing, which is not only beneficial to the removal of pollutants, but also reduces economic costs. In addition, the use of Fe ⁰ and AC as catalysts significantly increases the efficiency of activating PS to generate SO ₄ ^‑ ·, which is more conducive to the efficient treatment of alkaline waste liquid.

Description

A method for treating high-concentration refractory alkaline waste liquid with iron-carbon activated persulfate

technical field

The invention relates to the field of waste liquid treatment, in particular to a method for removing organic pollutants in high-concentration refractory alkaline waste liquid by using iron carbon to activate persulfate.

Background technique

Industrial waste liquid usually refers to dangerous goods with environmental hazards. Industrial waste liquid often has high pollutant concentration, complex water quality components, and poor biodegradability, which is an important content in the field of water pollution control. Common industrial waste liquid treatment methods mainly include biological treatment technology, physicochemical treatment technology and advanced oxidation treatment technology. Biological treatment technology generally requires low pollutant concentration, and high concentration treatment efficiency is low, especially alkaline industrial waste liquid, which is extremely biochemical. Low, pretreatment is usually required when entering the biological treatment unit, the traditional physical and chemical technology has low treatment efficiency, and the scope of application is small. Compared with the above two treatment techniques, chemical oxidation has a shorter treatment cycle, lower cost, and less damage to the environment. It has a more efficient and stable treatment effect on the chemical oxidation of organic pollutants that are generally difficult to treat. Based on the limitations of the chemical removal technology of alkaline waste liquid, Advanced Oxidation Processes technology has received more and more attention in the removal of alkaline waste liquid.

Advanced oxidation technology is characterized by producing a large number of hydroxyl groups with strong oxidizing ability as oxidants, and under the reaction conditions of high temperature and high pressure, electricity, sound, light irradiation, catalysts, etc., to degrade macromolecular organic pollutants into small molecules. Among them, Fenton oxidation technology is the most common traditional advanced oxidation technology. However, its wide application is limited by its narrow pH range (ie, acidity), high treatment cost, and large iron sludge output. In recent years, the advanced oxidation technology based on sulfate radicals has attracted more and more attention. Due to its high removal rate and high selectivity for refractory organic pollutants, it has developed into a new technology for the degradation of refractory organic wastewater. Generally, activated persulfate is used to generate highly active sulfate radicals, which can oxidize and degrade toxic organic pollutants in water, and promote the oxidative degradation of most refractory organic substances.

Compared with the large external energy required by the photocatalytic method and the complexity of the heating system of the thermocatalytic method, the use of transition metal ions as catalysts has a good effect on degrading pollutants, but some metal ions will cause secondary pollution to the environment. Although the efficiency of reaction between ions (Fe ²⁺ ) and persulfate to generate SO ₄ ^- · is relatively fast, it reduces the utilization rate of SO ₄ ^- ·, the catalyst has a short service life, low utilization rate, high processing cost and long time , is not conducive to the long-lasting, efficient and rapid removal of COD in wastewater. In summary, how to treat high-concentration refractory alkaline waste liquid more simply and efficiently has become an urgent problem in this technical field.

Contents of the invention

The object of the present invention is to address the deficiencies in the above-mentioned prior art, and to provide a method for treating high-concentration refractory alkaline waste liquid by using iron carbon to activate persulfate. Specifically, a certain amount of zero-valent iron (Fe ⁰ ), activated carbon (AC) and persulfate (PS) are added to the alkaline waste liquid containing refractory organic matter at normal temperature and pressure. The pollutants can be oxidized and degraded after reacting for 2 to 3 hours under the initial conditions.

The invention adds zero-valent iron and activated carbon to the alkaline waste liquid to activate the oxidant to generate sulfate radicals and hydroxyl radicals to oxidize pollutants, thereby degrading the alkaline waste liquid. Because iron carbon activates PS to produce SO ₄ ^- under alkaline conditions, it has a higher redox potential, and compared with the traditional Fenton oxidation technology, it has a wider pH range and saves the acid neutralization step. Not only is it beneficial to the removal of pollutants, but also reduces the economic cost. The present invention uses Fe ⁰ and AC as catalysts to significantly increase the efficiency of activating PS to produce SO ₄ ^- , and the action time is short, which is more conducive to the efficient treatment of alkaline waste liquid. The reaction system is simple to operate, saves acid neutralization, The solid PS is easy to transport, thus providing a new application of advanced oxidation technology in the treatment of alkaline industrial waste liquid.

In order to achieve the above object, the present invention provides a method for utilizing iron carbon activated persulfate to process high-concentration refractory alkaline waste liquid, which comprises the following steps:

(1) Add zero-valent iron, activated carbon and persulfate to high-concentration refractory alkaline waste liquid;

(2) Stir evenly, and the initial pH is an alkaline condition;

(3) React at room temperature for 2 to 3 hours to oxidize and remove pollutants.

Due to the large number of industrial enterprises in Suzhou City and the large output of hazardous materials such as waste liquid, environmental hazards are quite common. Industrial enterprises cannot meet the regulatory requirements for the waste liquid generated after treatment. At present, the waste liquid is often collected and processed in a centralized manner. The high-concentration refractory alkaline waste liquid of the present invention is a high-concentration refractory alkaline industrial waste liquid after dilution, and its initial COD value is 10160-10690 mg/L.

The mass ratio of zero-valent iron to activated carbon in the above step (1) is 2:1-6:1, preferably 3:1-5:1, and most preferably about 4:1.

In the above step (1), zero-valent iron and activated carbon are used as dual catalysts, and persulfate is used as an oxidizing agent.

The dosage of zero-valent iron in the above step (1) is 2.6～6.6g/L, the optimal dosage is 4.7g/L, the dosage of activated carbon is 1.1～1.3g/L, the optimal dosage It is 1.2g/L.

The persulfate in the above step (1) is preferably sodium persulfate, the dosage is 20-28g/L, and the optimum dosage is 22g/L, ie 0.092mol/L.

The dosages above are calculated based on the volume of high-concentration refractory alkaline waste liquid.

The stirring speed in the above step (2) is 200r/min, and the pH value is 10-11.

In the technical solution provided by the present invention, the iron is preferably zero-valent micron iron, and the activated carbon is powdered activated carbon with a particle size less than 100 mesh.

In the technical solution provided by the invention, the iron-carbon activated persulfate acts under alkaline conditions without adding acid for neutralization.

In addition, in the technical solution of the present invention, zero-valent iron and activated carbon are selected as dual catalysts, and persulfate is used as an oxidant to degrade high-concentration refractory alkaline waste liquid, which can obtain good removal effect.

The present invention comprises following beneficial effect:

1. The technical solution provided by the present invention adopts zero-valent iron and activated carbon as dual catalysts. Zero-valent iron can be used as a source of Fe ²⁺ to replace Fe ²⁺ to activate persulfate, release soluble Fe ²⁺ slowly, and avoid competition between excess Fe ²⁺ and sulfate radicals, thereby improving activation efficiency and achieving better degradation effect. Activated carbon is both a good adsorbent and a catalyst, and its surface oxygen-containing functional groups play an important role in the catalytic process. There is a remarkable synergistic effect between the two, so that the present invention produces an effect superior to that of the prior art.

2. Using persulfate as oxidant, persulfate substances have high water solubility. For example, the solubility of sodium persulfate in water can reach 73g/100g (25°C). Compared with liquid hydrogen peroxide, solid persulfate is in practical engineering In application, it is more convenient to transport, and the commercial price is cheap, so in practical engineering application, the cost is low and the operability is strong.

3. In the method provided by the present invention, under highly alkaline conditions (pH 10-11), iron carbon is activated to produce SO ₄ - , hydroxide ions can also activate persulfate to produce active free radicals, and degrade pollutants more efficiently , at the same time, hydrogen ions are also generated during the reaction process, which reduces the pH of the system and is more conducive to subsequent further processing. Utilizing the new advanced oxidation technology of persulfate to realize efficient treatment of high-concentration refractory waste liquid under alkaline conditions is a new technology discovered in recent years. The traditional advanced oxidation technology (Fenton oxidation technology) is often suitable for acidic environments, while The effect of alkaline conditions is poor; highly alkaline environment is not conducive to the growth of microorganisms. Before biological treatment, it is often necessary to add acid to neutralize the waste liquid, which requires a large amount of medicine consumption and high economic costs. And links, reducing economic costs; after the persulfate degrades pollutants, it can further generate hydrogen ions, reduce the pH of the system, and be more conducive to subsequent further treatment. Therefore, the technical solution of the present invention overcomes the problems of narrow applicable pH range and large iron slime output of the traditional Fenton, saves acid neutralization steps, reduces economic cost of treatment, and has good economic benefits.

4. The present invention also provides an application of persulfate advanced oxidation technology in the field of water treatment, which solves the difficult problem of refractory alkaline waste liquid treatment, greatly expands the scope of application of persulfate technology, and promotes the emergence of persulfate Promotion and application of technology in wastewater (liquid) treatment.

Description of drawings

Figure 1 is the COD degradation curve at 200r/min, with the same concentration of persulfate and different catalysts.

Figure 2 is the COD degradation curve under the condition of 200r/min, the same concentration of persulfate and micron zero-valent iron, and different concentrations of activated carbon (C).

Figure 3 is the COD degradation curve of different Fe and C dosages under the condition of 200r/min, the same concentration of persulfate, zero-valent iron and activated carbon (Fe/C)=4:1.

Figure 4 is the COD degradation curve under the conditions of 200r/min, different concentrations of persulfate, the same concentration of zero-valent iron and activated carbon.

Detailed ways

The specific implementation of the present invention will be described in detail below through several examples, but the claims of the present invention are not limited in any way.

In each of the following examples, uniformly collected and diluted high-concentration organic industrial wastewater with a COD ≥ 10,000 mg/L was used as the treatment sample.

Example 1

Take solid sodium persulfate (2.2g) and add it to 100ml of high-concentration organic industrial wastewater with pH = 10.5, add ① 0.47g of micron zero-valent iron (that is, micron-level zero-valent iron), ② 0.12g of C powder, and ③ micron zero-valent iron Valence iron 0.47g and C powder 0.12g. Put it in a water bath shaker and shake it at 200 r/min at room temperature for 3 hours to complete the removal of COD in high-concentration organic industrial wastewater by using persulfate solution. As shown in Figure 1: in the case of only adding C powder, the degradation rate of COD in wastewater within 3h is 76.2%; Close to 70.7%; when C powder and micron zero-valent iron are added, the degradation rate of COD in wastewater exceeds 86.4% within 3 hours, which well illustrates the process of activated carbon powder and zero-valent iron in the process of degrading COD by persulfate Can play a significant synergistic activation.

Example 2

Add 2.2g of sodium persulfate, 0.47g of micron zero-valent iron, and 0.06g, 0.09g, 0.12g and 0.16g of C powder into 100ml of high-concentration organic industrial wastewater with pH=10.5, and place them in a water bath shaker. 200r/min room temperature shaking reaction for 3h, that is to complete the removal of COD by using persulfate solution and micron zero-valent iron with different specific gravity and activated carbon powder. As shown in Figure 2, the removal rates of COD in this example reached 59.25%, 61.6%, 86.4%, and 60.8%, respectively, indicating that the effect is best when the ratio of zero-valent iron to activated carbon is about 4:1.

Example 3

Take 2.2g sodium persulfate, take 0.24g micron zero-valent iron and 0.06g carbon powder, 0.35g micron zero-valent iron and 0.09g carbon powder, 0.47g micron zero-valent iron and 0.12g carbon powder, 0.94g micron zero-valent iron and 0.24g of carbon powder, 1.88g of micron zero-valent iron and 0.47g of carbon powder were added to 100ml of high-concentration organic industrial wastewater with a pH of 10.5, placed in a water-bath oscillator and shaken for 3 hours at room temperature at 200r/min. That is, the removal of COD by using persulfate solution and different micron zero-valent iron and carbon powder dosage under the same iron-to-carbon ratio is completed. As shown in Figure 3, the removal rates of COD in this example reached 57.5%, 65.5%, 86.4%, 74.4%, and 76.2%, indicating that the optimal dosage of zero-valent iron and carbon powder was 4.7g/L and 1.2g/L.

Example 4

Take 0.47g of micron zero-valent iron and 0.12g of activated carbon, take 1.2g, 1.7g, 2.2g and 3.0g of sodium persulfate, add them to 100ml of high-concentration organic industrial wastewater with pH = 10.5, and place them in a water bath for oscillation The device was shaken and reacted at room temperature at 200r/min for 3h, and the removal of COD by using different concentrations of persulfate solutions was completed. As shown in Figure 4, the removal rates of COD in this example reached 73.0%, 75.8%, 86.4%, and 79.0%, respectively, indicating that the effect is the best when the dosage of sodium persulfate is 22g/L.

In summary, the present invention uses carbon powder and micron zero-valent iron as catalyzer, with persulfate as oxygenant, based on the principle that micron zero-valent iron catalyzes persulfate to produce sulfate radical, micron zero-valent iron activates PS (persulfate) Sulfate) produces SO ₄ ^- ·, which has a higher redox potential and a longer half-life than the hydroxyl radical in the Fenton oxidation process; at the same time, hydrogen ions are also generated during the reaction. This method can not only save the link of adding acid and neutralizing, and reduce economic costs; after the persulfate degrades pollutants, it can further generate hydrogen ions, reduce the pH of the system, and be more conducive to subsequent further processing; it can be carried out at room temperature, and the reaction conditions Mild; in addition, sulfate and zero-valent iron are relatively cheap and easy to obtain in daily life. Zero-valent iron is harmless to the human body and will not cause secondary pollution to the environment. At the same time, persulfate and micron zero-valent iron are solid particles, which are convenient Transportation is more practical and operable for the treatment of a large amount of actual wastewater, and the process cost is low. It has broad application prospects in the degradation and removal of COD in high-concentration organic industrial wastewater.

The above examples are preferred implementations of the present invention, and are only used to illustrate the present invention conveniently, and are not intended to limit the present invention in any form. Anyone with ordinary knowledge in the technical field, if they do not depart from the present invention, Within the scope of the technical features, the equivalent embodiments that make partial changes or modifications using the technical content disclosed in the present invention, and do not deviate from the technical features of the present invention, still belong to the scope of the technical features of the present invention.

Claims (10)

1. A kind of 1. method of iron carbon activation persulfate processing high-concentration hardly-degradable alkaline waste liquor, which is characterized in that the method Comprise the following steps：

   (1) Zero-valent Iron, activated carbon and persulfate are added into high-concentration hardly-degradable alkaline waste liquor；

   (2) stir evenly, initial pH is alkaline condition；

   (3) 2~3h is reacted at room temperature, you can oxidation removal polluter.
2. 2. according to the method described in claim 1, it is characterized in that, at the beginning of the step (1) middle and high concentration difficult degradation alkaline waste liquor Beginning COD value is 10160~10690mg/L.
3. 3. according to the method described in claim 1, it is characterized in that, the mass ratio of the Zero-valent Iron and activated carbon is 2: 1~6: 1。
4. 4. according to the method described in claim 3, it is characterized in that, the mass ratio of the Zero-valent Iron and activated carbon is about 4: 1.
5. 5. according to the method described in claim 1, it is characterized in that, Zero-valent Iron and activated carbon are urged as double in the step (1) Agent, for persulfate as oxidant, the persulfate is sodium peroxydisulfate.
6. 6. according to the method described in claim 5, it is characterized in that, in the step (1) dosage of Zero-valent Iron for 2.6~ 6.6g/L, the dosage of activated carbon is 1.1~1.3g/L.
7. 7. according to the method described in claim 1, it is characterized in that, in the step (1) dosage of persulfate for 20~ 28g/L。
8. 8. according to the method described in claim 1, it is characterized in that, the rotating speed of stirring is 200r/min, pH in the step (2) It is worth for 10~11.
9. 9. according to the method described in claim 1, it is characterized in that, the iron is zeroth order micron iron.
10. 10. according to the method described in claim 1, it is characterized in that, the activated carbon is less than 100 mesh powders activity for grain size Charcoal.