CN101269892A - A method for catalytic ozonation to remove organic matter in water - Google Patents

Abstract

The invention discloses a method for removing organic matter in water by catalyzing ozone oxidation, which belongs to the technical field of water treatment. It solves the problems of low ozone utilization rate, incomplete oxidation of organic pollutants, high cost and easy loss of catalyst in the existing method of ozone oxidation to remove organic matter in water, and the difficulty of applying in large-scale production and solid Catalysts suffer from surface inhomogeneity and slow internal diffusion. Method: 1. Water containing organic pollutants enters the ozone contact tower; 2. The effluent from the ozone contact tower enters a catalytic bed filled with zero-valent iron and filling materials. The present invention solves the problems of surface inhomogeneity and slow internal diffusion of solid catalysts, has the advantages of high catalytic activity, low cost, and the advantages of homogeneous catalytic oxidation and heterogeneous catalytic oxidation that catalysts are easily separated from water, and improves the efficiency of ozone. Utilization, and can be applied in mass production.

Description

A method for catalytic ozonation to remove organic matter in water

technical field

The invention belongs to the technical field of water treatment.

Background technique

Refractory organics in drinking water have the characteristics of low content, refractory degradation, and easy to magnify their harm through food chain bioaccumulation. Therefore, the pollution of refractory organics in water and the problem of effective treatment have become a severe problem facing my country's water environment work. question. Ozone is commonly used as an oxidant to remove organic matter in water, but the intermediate products generated by the decomposition of organic matter will prevent the further oxidation of ozone, reduce the utilization rate of ozone, and have side effects on water quality, and the subsequent treatment is complicated. In recent years, a series of advanced oxidation processes have been developed, such as O ₃ /H ₂ O ₂ , UV/O ₃ , UV/H ₂ O ₂ , UV/H ₂ O ₂ /O ₃ , O ₃ /metal oxide or photocatalytic Oxidation, the penetrating ability of ultraviolet rays in water is weak, the life of ultraviolet lamps is short, and regular maintenance is required. In addition, its efficiency in promoting ozone decomposition is not high, and the oxidation of organic pollutants is not complete. Hydrogen peroxide has remaining problems and consumes The residual chlorine in the water will increase the chlorine demand in the disinfection process, resulting in higher treatment costs. The metal-catalyzed ozone oxidation technology currently used, in the homogeneous catalytic oxidation, the catalyst is miscible in water, the catalyst is easy to lose and difficult to recycle, easy to produce secondary pollution, high operation and maintenance costs, increase processing costs, and difficult to produce on a large scale In heterogeneous catalytic oxidation, solid catalysts have the disadvantages of surface inhomogeneity and slow internal diffusion.

Contents of the invention

The purpose of the present invention is to solve the problem of low ozone utilization rate, insufficient oxidation of organic pollutants, high cost and easy loss of catalysts in the existing method of ozone oxidation to remove organic matter in water, and difficulty in large-scale production. Application, solid catalysts have the problems of surface inhomogeneity and slow internal diffusion speed, and provide a method for catalytic ozonation to remove organic matter in water.

A method for catalytic ozonation to remove organic matter in water is realized by the following steps: 1. Water containing organic pollutants enters an ozone contact tower, and the initial concentration of ozone in the water is controlled to be 0.5 to 2.0 mgO ₃ /mgTOC. The residence time is 5-20 minutes; 2. The effluent of the ozone contact tower enters the catalytic bed filled with zero-valent iron and filling materials, and the residence time of water in the catalytic bed is 5-20 minutes; among them, the zero-valent iron and filling materials are in accordance with the The volume ratio is 1-3:1 mixed; the zero-valent iron is pure iron powder, nano-iron powder or scrap iron; the filling material is activated carbon, coke, graphite, fly ash, charcoal, natural zeolite, artificial zeolite, activated alumina, One or a mixture of ceramsite and molecular sieve.

The present invention uses zero-valent iron as an active component to catalyze refractory organic pollutants in water for ozone oxidation, and the zero-valent iron can continuously produce Fe ²⁺ required for catalysis, and at the same time Fe _x O _y (y /x=1.5~1) also has a catalytic effect, both Fe ²⁺ and Fe _x O _y can catalyze the decomposition of ozone to generate hydroxyl radicals; Fe ²⁺ is oxidized by ozone to generate Fe ³⁺ , which can be quickly reduced to Fe ² by zero-valent iron ⁺ , to supplement the Fe ²⁺ required for catalytic oxidation. In addition, Fe _x O _y also has an adsorption effect on pollutants. It can increase the oxidation rate by enriching organic matter and ozone on the surface, which solves the problem of surface inhomogeneity and internal diffusion speed of solid catalysts. For slower problems, it has the advantages of high catalytic activity, low cost, and the catalyst is easy to separate from water. Homogeneous catalytic oxidation and heterogeneous catalytic oxidation can greatly improve the utilization rate of ozone, and can be applied in large-scale production.

Detailed ways

Specific Embodiment 1: In this embodiment, a method for catalytic ozonation to remove organic matter in water is realized by the following steps: 1. Enter the water containing organic pollutants into the ozone contact tower, and control the initial concentration of ozone in the water to 0.5-2.0 mgO ₃ /mgTOC , the residence time of water in the ozone contact tower is 5 to 20 minutes; 2. The effluent of the ozone contact tower enters the catalytic bed filled with zero-valent iron and filling materials, and the residence time of water in the catalytic bed is 5 to 20 minutes; Among them, the zero-valent iron and the filling material are mixed according to the volume ratio of 1 to 3:1; the zero-valent iron is pure iron powder, nano-iron powder or scrap iron; the filling material is activated carbon, coke, graphite, fly ash, charcoal, natural zeolite , artificial zeolite, activated alumina, ceramsite, molecular sieve or a mixture of several.

Embodiment 2: This embodiment differs from Embodiment 1 in that in step 1, the initial concentration of ozone in the water is controlled to be 1 mgO ₃ /mgTOC, and the residence time of water in the ozone contact tower is 10 min. Other steps and parameters are the same as those in Embodiment 1.

Specific embodiment three: the difference between this embodiment and specific embodiment one is that when the zero-valent iron used in step 2 is scrap iron scrap, the particle size of scrap iron scrap is 50nm～5mm; the scrap iron scrap is ground with a ball mill before use, Then sieve with a sieve with a pore size of 5 mm, wash with 0.5 mol/L hydrochloric acid after sieving, and then activate with 0.5 mol/L sodium hydroxide. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 4: This embodiment differs from Embodiment 1 in that the particle size of the filling material in Step 2 is 0.5-5 mm. Other steps and parameters are the same as in the first embodiment.

Embodiment 5: This embodiment is different from Embodiment 1 in that the particle size of the filling material in step 2 is 2 mm. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 6: This embodiment is different from Embodiment 1 in that the residence time of water in the catalytic bed in step 2 is 10 min. Other steps and parameters are the same as in the first embodiment.

Embodiment 7: The difference between this embodiment and Embodiment 1 is that in step 2, the zero-valent iron and the filling material are mixed in a volume ratio of 2:1. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 8: In this embodiment, a method for catalytic ozonation to remove organic matter in water is realized by the following steps: 1. Water containing organic pollutants is entered into the ozone contact tower, and the initial concentration of ozone in the water is controlled to be 1mgO ₃ /mgTOC, and the water is The residence time in the ozone contact tower is 15min; 2. The effluent of the ozone contact tower enters the catalytic bed filled with waste iron scraps and packing materials inside, and the residence time of water in the catalytic bed is 15min; wherein the scrap iron scraps and packing materials Mixed according to the volume ratio of 2:1; the filling material is a mixture of activated carbon, coke, natural zeolite and ceramsite.

In this embodiment, the removal rate of organic pollutants is as high as 60-95%, and the utilization efficiency of ozone is as high as 70-90%.

Specific embodiment nine: In this embodiment, a method for catalytic ozonation to remove organic matter in water is realized by the following steps: 1. Enter the water containing organic pollutants into the ozone contact tower, and control the initial concentration of ozone in the water to be 1mgO ₃ /mgTOC, and the water is The residence time in the ozone contact tower is 15min; 2. The effluent of the ozone contact tower enters the catalytic bed filled with pure iron powder and packing material inside, and the residence time of water in the catalytic bed is 15min; The volume ratio is 1.5:1; the filling material is a mixture of fly ash, charcoal and artificial zeolite.

In this embodiment, the removal rate of organic pollutants is as high as 60-90%, and the utilization efficiency of ozone is as high as 70-90%.

Claims (7)

1. A method for catalytic ozonation to remove organic matter in water, characterized in that a method for catalytic ozonation to remove organic matter in water is realized in the following steps: 1. Water containing organic pollutants is entered into an ozone contact tower to control the initial concentration of ozone in water 0.5~2.0mgO ₃ /mgTOC, the residence time of water in the ozone contact tower is 5~20min; 2. The effluent of the ozone contact tower enters the catalytic bed filled with zero-valent iron and packing materials, and the water in the catalytic bed The residence time is 5-20min; the zero-valent iron is mixed with the filling material at a volume ratio of 1-3:1; the zero-valent iron is pure iron powder, nano-iron powder or scrap iron; the filling material is activated carbon, coke, graphite, One or more of fly ash, charcoal, natural zeolite, artificial zeolite, activated alumina, ceramsite, and molecular sieve. 2. A method for removing organic matter in water by catalytic ozone oxidation according to claim 1, characterized in that in step 1, the initial concentration of ozone in water is controlled to be 1 mgO ₃ /mgTOC, and the residence time of water in the ozone contact tower is 10 min. 3. A method for catalytic ozonation to remove organic matter in water according to claim 1, characterized in that when the zero-valent iron used in step 2 is scrap iron scrap, the particle size of scrap iron scrap is 50nm to 5mm; Grind with a ball mill before use, then sieve with a sieve with a pore size of 5 mm, wash with 0.5 mol/L hydrochloric acid after sieving, and then activate with 0.5 mol/L sodium hydroxide. 4. A method for removing organic matter in water by catalytic ozone oxidation according to claim 1, characterized in that the particle size of the filling material in step 2 is 0.5-5mm. 5. A method for catalytic ozonation to remove organic matter in water according to claim 1, characterized in that the particle size of the filling material in step 2 is 2mm. 6. A method for catalytic ozonation to remove organic matter in water according to claim 1, characterized in that the residence time of water in the catalytic bed in step 2 is 10 minutes. 7. A method for catalytic ozonation to remove organic matter in water according to claim 1, characterized in that in step 2, zero-valent iron and filling material are mixed at a volume ratio of 2:1.