Method for degrading wastewater containing high-concentration isopropanol by ozone catalytic oxidation

Abstract

The application discloses a method for degrading wastewater containing high-concentration isopropyl alcohol by ozone catalytic oxidation. Magnesium oxide is added into the wastewater containing high-concentration isopropyl alcohol as a catalyst, and ozone is introduced to perform ozone catalytic reaction. The wastewater after degradation is obtained after the reaction is completed. The method can reduce the COD of the wastewater containing high-concentration isopropyl alcohol from 5000 mg / L to below 500 mg / L in a short time, and the removal rate can reach above 90%. Since the reaction time is short, the required reaction structure volume is small, and the land occupation area is saved. The method can directly act on the wastewater containing high-concentration isopropyl alcohol, and degradation is relatively complete.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for treating industrial wastewater, in particular to a method for catalytic ozonation degradation of high-concentration isopropyl alcohol-containing wastewater. BACKGROUND

[0002] High-concentration isopropyl alcohol-containing wastewater mainly comes from the production processes of rubber, electronics industry, plastics and other industries. The concentration of isopropyl alcohol discharged in the production process of monocrystalline silicon cells in the photovoltaic industry is very high, and the COD is as high as 40,000 mg / L. This part of the waste liquid is generally disposed as hazardous waste. When disposing this kind of waste liquid, the hazardous waste disposal unit generally recovers isopropyl alcohol by rectification. The residual liquid after rectification still contains 2%-3% of isopropyl alcohol, forming the final wastewater that needs to be treated. The COD of this part of wastewater is about 5,000 mg / L. The isopropyl alcohol of this concentration is toxic to microorganisms, and biochemical treatment is not suitable. Advanced oxidation technology (AOPs) can often be used for the degradation of this kind of high-concentration industrial wastewater. Among them, ozone catalytic oxidation technology is widely used. However, due to the difference of the treatment object, different types and functions of catalysts need to be used, and certain reaction conditions need to be maintained. For high-concentration isopropyl alcohol-containing wastewater, how to select the appropriate catalyst and set the reaction conditions becomes the key to solving the problem.

[0003] Biochemical method for treating high-concentration isopropyl alcohol-containing wastewater must be diluted to medium concentration, and the wastewater quantity is increased, which will cause the increase of the hydraulic load of the biochemical structure, and the structure needs to be expanded if necessary. Moreover, biochemical method needs a long hydraulic retention time and a large volume, and a large amount of sludge is produced. Under the condition of no low-concentration wastewater or no sufficient retention time for biochemical treatment, how to degrade the isopropyl alcohol in a short time is a problem to be solved. At present, there is no effective catalyst for ozone catalytic oxidation technology for high-concentration isopropyl alcohol-containing wastewater.

[0004] Isopropyl alcohol itself is a biodegradable substance, but high-concentration isopropyl alcohol-containing wastewater with a COD concentration of 5,000 mg / L is toxic to microorganisms, and biochemical treatment is not suitable. Therefore, it is often mixed with other low-concentration wastewater to reduce the COD to 2,000 mg / L-3,000 mg / L before biochemical treatment. SUMMARY

[0005] The purpose of the present application is to provide a method for catalytic ozonation degradation of high-concentration isopropyl alcohol-containing wastewater, which can greatly reduce the concentration of high-concentration isopropyl alcohol in a short time.

[0006] Technical scheme: The method for catalytic ozonation degradation of high-concentration isopropyl alcohol-containing wastewater according to the present application adds magnesium oxide as a catalyst to high-concentration isopropyl alcohol-containing wastewater, and introduces ozone to carry out catalytic ozonation reaction. After the reaction is completed, the degraded wastewater is obtained.

[0007] The mass ratio of the ozone to the high-concentration isopropyl alcohol-containing wastewater is 1:10-1:200, and more preferably 1:80-1:120.

[0008] The mass ratio of the catalyst to the high-concentration isopropyl alcohol-containing wastewater is 1:100-1:1000, and more preferably 1:500-1:700.

[0009] The pH range of the ozone catalytic oxidation reaction is 6-10, and more preferably 7.

[0010] The ozone catalytic reaction time is 0.5-5h, and more preferably 1.5-3h.

[0011] The ozone catalytic oxidation reaction is carried out at normal temperature and pressure.

[0012] The particle size of the magnesium oxide is 20nm-100μm, and more preferably 100nm-100μm.

[0013] The ozone source is an air source or an oxygen source. The ozone generation amount of the oxygen source or the air source can be 5-1000g / h, and can vary according to the water quality and the water quantity.

[0014] The reactor used in the ozone catalytic reaction is one of a fixed bed, a moving bed and a fluidized bed.

[0015] The principle of the ozone catalytic oxidation technology is that the electrons on the surface of the catalyst are excited in the presence of ozone, the electron holes generated on the surface of the catalyst have strong oxidizing properties, and at the same time, the ozone molecules are also partially converted into O3· free radicals, which also have strong oxidizing properties. The ozone molecules that are not converted into O3· free radicals also have strong oxidizing properties. These substances with strong oxidizing properties act together on the isopropyl alcohol molecules in the wastewater, and completely oxidize the isopropyl alcohol molecules into CO2 and H2O, which is manifested as a decrease in the COD of the final wastewater.

[0016] Beneficial effects: Compared with the prior art, the method of the present application can reduce the COD of the high-concentration isopropyl alcohol-containing wastewater from 5000mg / L to below 500mg / L in a short time, and the removal rate can be above 90%. Since the reaction time is short, the required reaction structure volume is small, and the land occupation area is saved. The method can directly act on the high-concentration isopropyl alcohol-containing wastewater, and the degradation is relatively complete. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below.

[0018] Example 1

[0019] In 1 L measuring cylinder, 300 ml of high concentration isopropyl alcohol containing wastewater with COD of 5000 mg / L was placed, 3 g of magnesium oxide with particle size of 10 μm was added into the measuring cylinder, i.e. the mass ratio of magnesium oxide to wastewater was 1:100, 10 g / h of ozone generated from oxygen source was introduced into the measuring cylinder, the pH of the system was adjusted to 7.0, and the ozone catalytic reaction was carried out for 3 h, i.e. the mass ratio of introduced ozone to wastewater was 1:10.

[0020] After the reaction, the wastewater sample was taken for detection, and the COD was 460 mg / L, and the COD removal rate was 90.8%.

[0021] Example 2

[0022] In 1 L measuring cylinder, 500 ml of high concentration isopropyl alcohol containing wastewater with COD of 5000 mg / L was placed, 1 g of magnesium oxide with particle size of 10 μm was added into the measuring cylinder, i.e. the mass ratio of magnesium oxide to wastewater was 1:500, 10 g / h of ozone generated from oxygen source was introduced into the measuring cylinder, the pH was 7.0, and the ozone catalytic reaction was carried out for 0.5 h, i.e. the mass ratio of introduced ozone to wastewater was 1:100. After the reaction, the wastewater sample was taken for detection, and the COD was 650 mg / L, and the COD removal rate was 87%.

[0023] Example 3

[0024] In 1 L measuring cylinder, 500 ml of high concentration isopropyl alcohol containing wastewater with COD of 5000 mg / L was placed, 0.71 g of magnesium oxide with particle size of 100 nm was added into the measuring cylinder, i.e. the mass ratio of magnesium oxide to wastewater was 1:700, 10 g / h of ozone generated from oxygen source was introduced into the measuring cylinder, the pH was 7.0, and the ozone catalytic reaction was carried out for 5 h, i.e. the mass ratio of introduced ozone to wastewater was 1:10. After the reaction, the wastewater sample was taken for detection, and the COD was 440 mg / L, and the COD removal rate was 91.2%.

[0025] Example 4

[0026] In 2 L beaker, 1000 ml of high concentration isopropyl alcohol containing wastewater with COD of 5000 mg / L was placed, 1 g of magnesium oxide with particle size of 10 μm was added into the beaker, i.e. the mass ratio of magnesium oxide to wastewater was 1:1000, 10 g / h of ozone generated from oxygen source was introduced into the measuring cylinder, the pH of the system was adjusted to 7.5, and the ozone catalytic reaction was carried out for 0.5 h, i.e. the mass ratio of introduced ozone to wastewater was 1:200.

[0027] After the reaction, the wastewater sample was taken for detection, and the COD was 680 mg / L, and the COD removal rate was 86.4%.

Claims

1. A method for ozone catalytic oxidation degradation of wastewater containing high concentrations of isopropanol, characterized in that, Magnesium oxide was added as a catalyst to wastewater containing high concentrations of isopropanol, and ozone was introduced to carry out an ozone catalytic reaction. After the reaction was completed, the degraded wastewater was obtained. The magnesium oxide has a particle size of 20 nm to 100 μm; The mass ratio of ozone introduced to wastewater containing high concentrations of isopropanol is 1:10-1:200; the mass ratio of magnesium oxide to wastewater containing high concentrations of isopropanol is 1:100-1:1000. The pH range of the ozone catalytic oxidation reaction is adjusted to 6-10; the time of the ozone catalytic reaction is 0.5-5h.

2. The method for ozone catalytic oxidation degradation of wastewater containing high concentrations of isopropanol according to claim 1, characterized in that, The ozone catalytic oxidation reaction is carried out at room temperature and pressure.

3. The method for ozone catalytic oxidation degradation of wastewater containing high concentrations of isopropanol according to claim 1, characterized in that, The ozone source is either air or oxygen.

4. The method for ozone catalytic oxidation degradation of wastewater containing high concentrations of isopropanol according to claim 1, characterized in that, The reactor used for the ozone catalytic reaction is one of a fixed bed, a moving bed, or a fluidized bed.