CN114644388A - A kind of catalytic oxidation treatment method of sulfur-containing wastewater - Google Patents

Abstract

The invention discloses a catalytic oxidation treatment method of sulfur-containing wastewater, which comprises the following steps: firstly, mixing sulfur-containing wastewater and hydrogen peroxide through a mixer; then, the mixture enters a catalytic reactor to carry out catalytic reaction. The invention has simple process, convenient operation, good catalytic effect and no secondary pollution, the catalyst can be repeatedly used, and the treated water can be reused for production.

Description

A kind of catalytic oxidation treatment method of sulfur-containing wastewater

technical field

The invention relates to a method for treating sulfur-containing wastewater, which belongs to the technical field of industrial refractory wastewater treatment in the environmental protection industry.

Background technique

Sulfur-containing wastewater has the characteristics of strong odor and toxicity, which will not only corrode equipment, but also cause serious pollution to the environment. The treatment methods of sulfur-containing wastewater include biological treatment method and chemical method. Commonly used are chemical methods, mainly lye absorption method, chemical precipitation method and chemical oxidation method. Among them, the lye absorption method will produce hydrogen sulfide and the process is complicated, so it is generally not used alone; the chemical precipitation method has the problem of subsequent treatment of the precipitation, and the process is also complicated; the chemical oxidation method has advanced oxidation and chemical oxidation (hydrogen peroxide, ozone, high manganese). Potassium acid, chlorine, etc.), chemical oxidation method has low oxidation rate (hydrogen peroxide) or high price (ozone, potassium permanganate, chlorine, etc.); in advanced oxidation method, wet oxidation treatment effect is better, but the cost is high.

SUMMARY OF THE INVENTION

In order to solve the deficiency of the existing advanced treatment of sulfur-containing wastewater, the present invention proposes a catalytic oxidation treatment process for sulfur-containing wastewater with simple process and no secondary pollution. The catalyst used in this process has no secondary pollution, and the sulfur ion in the treated effluent reaches the national first-class emission standard.

The invention uses hydrogen peroxide as an oxidant and selects a heterogeneous catalyst to treat sulfur-containing wastewater, thereby solving the problems of complex sulfur-containing wastewater treatment process, low oxidation rate and high treatment cost. Moreover, the treated wastewater can be reused for production, which further improves the economy.

The invention provides a method for treating sulfur-containing wastewater by catalytic oxidation, which comprises the following steps: mixing sulfur-containing wastewater with a solution containing an oxidant, and contacting and reacting with a catalyst; the catalyst used is a supported catalyst, and Al ₂ O ₃ is used as a carrier to support M element. wherein, the M element is selected from any one of Mn, Fe, Co, Ni, Cu, and Zn; the content of the M element is 0.2-5wt.% of the Al ₂ O ₃ carrier.

For the mixing method described in the present invention, those skilled in the art can select conventional mixing means and equipment according to actual needs, for example, a mixer can be used for mixing, preferably a cyclone mixer.

The reaction in contact with the catalyst described in the present invention preferably adopts a catalytic reactor, and those skilled in the art can select a conventional catalytic reactor according to actual needs, such as a fixed-bed catalytic reactor or a fluidized-bed catalytic reactor; Sulfur-containing waste water and oxidant enter the catalytic reactor, where sulfur ions contact the catalyst for oxidation reaction.

The catalyst used in the present invention is a supported catalyst, M/Al ₂ O ₃ , which belongs to a heterogeneous catalyst, and is usually prepared by an impregnation method, a co-precipitation method or a co-mixing method. Mix, shape, fire. Those skilled in the art can select a compound containing M element according to actual needs. Usually, M salt or organic M compound can be dissolved in the corresponding solvent. Common choices are: Mn, Fe, Co, Ni, Cu, Zn and other transition metals of nitrates, sulfates or chlorides.

Preferably, the sulfur ion concentration of the sulfur-containing wastewater is less than 500 mg/L.

Preferably, the oxidant is hydrogen peroxide.

Preferably, the mass fraction of the hydrogen peroxide is 20-30 wt.%, and the hydrogen peroxide is added in an amount of 4-20 in a H ₂ O ₂ /S ^2- molar ratio.

Preferably, the reaction temperature is 20-40°C; the reaction pressure is normal pressure; the hourly space velocity of the sulfur-containing waste water liquid is 0.5-2 h ^-1 .

Preferably, when the reaction temperature is 20-40°C, the reaction pressure is normal pressure, and the waste water liquid hourly space velocity is 0.5-2 h ^-1 , the removal rate of sulfur ions is more than 90%.

The invention optimizes the existing process conditions for the treatment of sulfur-containing wastewater, adopts the supported transition metal catalyst, can directly treat the sulfur-containing wastewater, obviously improves the removal rate of sulfur ions, greatly simplifies the treatment process, and effectively Therefore, the treatment cost of sulfur-containing wastewater is greatly reduced.

Description of drawings

Figure 1. Evaluation results of continuous reaction of Cat1 catalyst for treating low-concentration sulfur-containing wastewater.

Detailed ways

The present invention adopts H ₂ O ₂ as an oxidant in a reactor containing M/Al ₂ O ₃ heterogeneous catalyst under the conditions of reaction temperature of 20-40° C. and reaction pressure and normal pressure to remove sulfides in sulfur-containing wastewater Advanced treatment process for oxidation to sulfate.

The sulfur-containing wastewater catalytic oxidation treatment method of the present invention mainly includes two-stage process:

The first stage: the sulfur-containing wastewater is mixed with H ₂ O ₂ and then enters the catalytic reactor.

Second stage: Sulfide ion or thiocyanate is oxidized on the catalyst.

The second stage is the key to this process. The oxidation process is as follows: First, H ₂ O ₂ generates hydroxyl radicals with strong oxidizing properties on the M/Al ₂ O ₃ catalyst; then, the hydroxyl radicals convert sulfide ions or thiocyanates oxidized to sulfate.

The equation for this stage is as follows:

S ^2- +8HO·→SO ₄ ^2- +4H ₂ O

Sulfur ion content in water was analyzed by iodometric method (HJT 60-2000).

The technology of the present invention will be further described below through examples.

Example 1

A solution of ferric nitrate and copper nitrate was used to prepare 1wt.%Fe1wt.%Cu/Al ₂ O ₃ by equal volume impregnation, overnight impregnation, drying at 120°C for 4h, and calcination at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =4, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the hourly space velocity of waste water was LHSV=1h ^-1 . The evaluation results are shown in Table 1.

Table 1 Sulfide ion removal effect when adding different amounts of hydrogen peroxide

Example 2

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by the equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =8, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=1h ^-1 . The evaluation results are shown in Table 1.

Example 3

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by the equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=1h ^-1 . The evaluation results are shown in Table 1.

Example 4

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =16, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=1h ^-1 . The evaluation results are shown in Table 1.

It can be seen from the experimental results in Table 1 that in the range of H ₂ O ₂ /S ^2- molar ratio of 4 to 16, the removal rate of sulfur ions reaches more than 90%, and with the increase of H ₂ O ₂ /S ^2- molar ratio , the sulfur ion removal rate continued to increase.

Example 5

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat2.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=0.5h ^-1 . The evaluation results are shown in Table 2.

Table 2 Sulfide ion removal effect at different influent air velocity

Example 6

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=1.5h ^-1 . The evaluation results are shown in Table 2.

Example 7

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by the equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, reaction temperature was 25°C, reaction pressure was normal pressure, and space velocity LHSV=2.0h ^-1 . The evaluation results are shown in Table 2.

From the experimental results in Table 2, it can be seen that when the H ₂ O ₂ /S ^2- molar ratio is 12, the influence of ^LHSV is investigated. At 2h ^-1 , the removal rate of sulfur ions still reached more than 90%.

Example 8

1wt.% Fe1wt.%Cu/Al ₂ O ₃ was prepared by the equal volume impregnation method, impregnated overnight, dried at 120℃ for 4h, and calcined at 500℃ for 4h to prepare the desired catalyst Cat1; the same method was used to prepare 2wt.%Fe/Al ₂ O _3. 1wt.%Fe1wt.%Mn/ _Al2O3 , 1wt.% _Cu1wt .%Mn/ _Al2O3 catalysts, respectively _denoted as Cat2, Cat3, Cat4.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, the reaction temperature was 25°C, the reaction pressure was normal pressure, and the space velocity was LHSV=1h ^-1 . The evaluation results are shown in Table 3.

It can be seen from the experimental results in Table 3 that under the conditions of H ₂ O ₂ /S ^2- molar ratio of 12 and space velocity of LHSV=1h ^-1 , the removal effects of various catalysts on sulfide ions were investigated. The results show that the catalyst Cat1 (1wt.%Fe1wt.%Cu/Al ₂ O ₃ ) has the best removal effect on sulfur-containing wastewater.

Table 3 Sulfide ion removal effect with different catalysts

Example 9

1wt.%Fe1wt.%Cu/Al ₂ O ₃ was prepared by the equal volume impregnation method, impregnated overnight, dried at 120°C for 4h, and calcined at 500°C for 4h to prepare the desired catalyst Cat1.

Reaction conditions: hydrogen peroxide was added at a molar ratio of H ₂ O ₂ /S ^2- =12, reaction temperature was 25°C, reaction pressure was normal pressure, space velocity LHSV=1h ^-1 , and continuous reaction was carried out. The evaluation results are shown in Figure 1 .

As shown in Figure 1, the catalyst Cat1 (1wt.%Fe1wt.%Cu/Al ₂ O ₃ ) has a better removal effect on sulfur-containing wastewater, the removal rate of sulfur ions reaches more than 96%, and the activity has no attenuation after stable operation for 168h. .

Claims (6)

1. A catalytic oxidation treatment method for sulfur-containing wastewater is characterized by comprising the following steps:

mixing the sulfur-containing wastewater with a solution containing an oxidant, and carrying out contact reaction with a catalyst;

the catalyst is a supported catalyst and is made of Al₂O₃The carrier is loaded with M element;

wherein, the M element is selected from any one of Mn, Fe, Co, Ni, Cu and Zn;

the content of M element is Al₂O₃0.2 to 5wt.% of the support.

2. The catalytic oxidation treatment method for sulfur-containing wastewater according to claim 1, wherein the sulfur ion concentration of the sulfur-containing wastewater is less than 500 mg/L.

3. The catalytic oxidation treatment method for sulfur-containing wastewater according to claim 1, wherein the oxidant is hydrogen peroxide.

4. The catalytic oxidation treatment method for sulfur-containing wastewater according to claim 3, wherein the mass fraction of the hydrogen peroxide is 20-30 wt.%, and the addition amount of the hydrogen peroxide is H₂O₂/S^2-The molar ratio is 4-20.

5. The catalytic oxidation treatment method for sulfur-containing wastewater according to claim 1, wherein the reaction temperature is 20 to 40 ℃; the reaction pressure is normal pressure; the hourly space velocity of the sulfur-containing wastewater liquid is 0.5-2 h^-1。

6. The catalytic oxidation treatment method of sulfur-containing wastewater according to claim 2, wherein the reaction temperature is 20 to 40 ℃, the reaction pressure is normal pressure, and the hourly space velocity of wastewater liquid is 0.5 to 2 hours^-1Under the condition, the removal rate of the sulfur ions reaches over 90 percent.

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