阅读说明：本技术 一种乙醛强化光降解废水中的有机染料的方法 (Method for performing enhanced photodegradation on organic dye in wastewater by using acetaldehyde ) 是由 徐焕志 张保平 高佳俊 吴亦茹 姚冰 于 2019-09-26 设计创作，主要内容包括：本发明涉及污水处理领域,尤其涉及一种乙醛强化光降解废水中的有机染料的方法。包括以下步骤：向含有有机染料的废水中加入一定量的双氧水搅拌一定时间后,得到微氧化废水；然后向微氧化废水中加入一定量的乙醛溶液后,得到前处理液并将前处理液通入内部设置有多层光催化板的容器中,然后对容器中照射紫外光一定时间,得到降解废水；所述光催化板表面含有一定量的金属银以及稀土元素。本发明克服了现有技术中的光降解废水中有机染料的方法所用到的光催化效率较低,同时循环利用性能较差的缺陷,具有能够在低紫外光强度的条件下快速降解水中有机染料的优点,同时光催化促进剂添加含量低,光催化效率不会随时间推移而降低。(The invention relates to the field of sewage treatment, in particular to a method for performing enhanced photodegradation on organic dye in wastewater by using acetaldehyde. The method comprises the following steps: adding a certain amount of hydrogen peroxide into the wastewater containing the organic dye, and stirring for a certain time to obtain micro-oxidation wastewater; then adding a certain amount of acetaldehyde solution into the micro-oxidation wastewater to obtain a pretreatment solution, introducing the pretreatment solution into a container with a plurality of layers of photocatalytic plates arranged inside, and irradiating ultraviolet light in the container for a certain time to obtain degradation wastewater; the surface of the photocatalytic plate contains a certain amount of metallic silver and rare earth elements. The method overcomes the defects of low photocatalytic efficiency and poor recycling performance of the method for photodegrading the organic dye in the wastewater in the prior art, has the advantage of rapidly degrading the organic dye in the water under the condition of low ultraviolet light intensity, and has low addition content of the photocatalytic promoter, so that the photocatalytic efficiency cannot be reduced along with the lapse of time.)

1. A method for acetaldehyde enhanced photodegradation of organic dyes in wastewater, comprising the steps of:

(1) micro-oxidation treatment: adding a certain amount of hydrogen peroxide into the wastewater containing the organic dye, and stirring for a certain time to obtain micro-oxidation wastewater;

(2) preparation of a pretreatment liquid: adding a certain amount of acetaldehyde solution into the micro-oxidation wastewater to obtain a pretreatment solution;

(3) ultraviolet light catalysis: introducing the pretreatment liquid into a container with a plurality of layers of photocatalytic plates arranged inside, and irradiating ultraviolet light in the container for a certain time to obtain degraded wastewater;

the surface of the photocatalytic plate contains a certain amount of metallic silver and rare earth elements.

2. The method for strengthening the organic dye in the photodegradation wastewater of acetaldehyde according to claim 1, wherein the adding amount of hydrogen peroxide in the step (1) is 0.001 ~ 0.05.05% of the mass of the wastewater, and the stirring is carried out for 30 ~ 90 min.

3. The method for enhancing the organic dye in the photodegradation of wastewater by acetaldehyde according to claim 1, wherein the acetaldehyde content in the step (2) is 300 ~ 1500 ppm.

4. The method for performing enhanced photodegradation of organic dyes in wastewater with acetaldehyde according to claim 1, wherein the method for preparing the photocatalytic plate in the step (3) is as follows:

(S.1) preparing the rare earth-containing aerogel: stirring and mixing tetraethoxysilane, rare earth powder, an acid catalyst and an absolute ethyl alcohol solvent, standing, heating and aging to obtain wet sol, and performing supercritical treatment to obtain rare earth aerogel;

(S.2) depositing metallic silver on the surface: crushing the rare earth aerogel, adding the crushed rare earth aerogel into a silver ammonia solution, uniformly mixing, then dripping a glucose solution into the mixture, stirring the mixture in a water bath for a certain time, and filtering and drying the mixture to obtain rare earth aerogel powder with metal silver deposited on the surface;

(S.3) sintering and forming: the rare earth aerogel powder with the surface deposited with the metal silver is subjected to uniaxial compression to obtain a slab, and then the slab is sintered at high temperature to obtain the photocatalytic plate.

5. The method for enhancing the organic dye in the photodegradation wastewater of acetaldehyde according to claim 4, wherein the mass ratio of tetraethoxysilane to rare earth powder in the step (S.1) is 100 (1 ~ 5), the pH of the solution is adjusted to 2 ~ 3.5.5 by the acid catalyst, and the stirring reaction is carried out for 20 ~ 40 min.

6. The method for strengthening organic dye in wastewater by light degradation of acetaldehyde according to claim 4 or 5, wherein the rare earth powder of step (S.1) comprises 20 parts by weight of cerium oxide 20 ~ 35, 10 parts by weight of europium oxide 10 ~ 15, 10 parts by weight of lanthanum oxide 10 ~ 15 and 3 parts by weight of ytterbium oxide 3 ~ 8.

7. The method for acetaldehyde enhancement of organic dye in photodegradation wastewater as claimed in claim 4 or 5, wherein the aging temperature in the step (S.1) is 65 ~ 75 ℃, the aging time is 1 ~ 3h, the supercritical temperature is 250 ~ 280 ℃, and the supercritical pressure is 5 ~ 8 MPa.

8. The method for performing enhanced photodegradation of organic dyes in wastewater by acetaldehyde according to claim 4, wherein the mass ratio of the rare earth aerogel to the silver ammonia solution in the step (S.2) is (10 ~ 35) to 100, the mass fraction of the glucose solution is 20 ~ 30%, the volume ratio of the silver ammonia solution to the glucose solution is 100 (0.2 ~ 0.5), and the water bath temperature is 60 ~ 65 ℃.

9. The method of claim 4, wherein the uniaxial compression pressure in the step (S.3) is 8 ~ 12MPa, the sintering temperature is 600 ~ 850 ℃ and the sintering atmosphere is nitrogen.

10. The method for enhanced photodegradation of organic dyes in wastewater by acetaldehyde as claimed in claim 1, wherein the ultraviolet emission wavelength of step (3) is 254nm, and the irradiation intensity is 120 ~ 150uW/cm²The irradiation time was 10 ~ 30 min.

Technical Field

The invention relates to the field of sewage treatment, in particular to a method for performing enhanced photodegradation on organic dye in wastewater by using acetaldehyde.

Background

Wastewater produced by the textile industry is a widespread and important pollution problem worldwide and should be valued for such industrial wastewater treatment. These industries produce a wide variety of waste waters including large amounts of contaminants such as acidic materials, corrosive materials, toxic organic and inorganic materials, soluble solids, dyes, and the like. Among textile waste water, biodegradation of reactive dye waste water is the most difficult.

Currently, 8 x 10 is produced worldwide each year⁵t, which are widely used in the industries of food, textile, printing and dyeing, leather manufacturing and the like. The dye lost throughout the dye production process accounted for 15% of the total dye yield. The dye wastewater has the characteristics of large water quantity, high organic matter content, high chroma, three-cause toxicity and the like. If the treatment is improper, serious threats can be brought to the ecological environment and the human health. Common dye wastewater treatment methods mainly comprise an adsorption method, a coagulation-flocculation method, a biological method, a membrane separation method and the like. The adsorption technology is widely applied to dye wastewater treatment because of the characteristics of easy operation, low cost, high efficiency and the like. The specific surface area of the adsorbent is low, and the difficulty in separation and recovery becomes the bottleneck of the high-efficiency treatment of the dye wastewater by the current adsorption method.

Furthermore, the treatment of dye-containing waste water is generally also carried out chemically, for example by accelerating the precipitation of dye molecules with coagulants, but the sludge produced requires careful subsequent treatment. In addition, ozone is used to decompose the dye, but this technique is expensive.

For example, a visible light catalyst with publication number CN105600868A for degrading various organic dyes, in particular to an application of octa-carboxyl iron phthalocyanine sensitized titanium dioxide catalyst in degrading organic dyes under visible light. The catalyst of the invention has the advantages that: 1. the water solubility is good; 2. the supported catalyst avoids the agglomeration of metal phthalocyanine; 3. expanding ultraviolet light catalysis to visible light catalysis; 4. can degrade five dyes in the waste water simultaneously. By carrying out degradation tests on methylene blue, rhodamine B, neutral red, acid red and malachite green under the condition of visible light, the octacarboxyl iron phthalocyanine successfully expands the light absorption range of titanium dioxide from an ultraviolet light region to a visible light region, improves the light utilization rate, further enhances the degradation effect on organic dye wastewater, but has the defects of low decomposition efficiency and poor recycling performance.

Disclosure of Invention

The invention provides a method for degrading organic dye in wastewater by acetaldehyde enhancement light, aiming at overcoming the defects of low photocatalysis efficiency and poor recycling performance of a method for degrading organic dye in wastewater by light in the prior art, and the method can rapidly degrade the organic dye in the wastewater by light under the condition of low ultraviolet light intensity and can recycle the organic dye.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a method for acetaldehyde enhanced photodegradation of organic dyes in wastewater, the method comprising the steps of:

(1) micro-oxidation treatment: adding a certain amount of hydrogen peroxide into the wastewater containing the organic dye, and stirring for a certain time to obtain micro-oxidation wastewater;

(2) preparation of a pretreatment liquid: adding a certain amount of acetaldehyde solution into the micro-oxidation wastewater to obtain a pretreatment solution;

(3) ultraviolet light catalysis: introducing the pretreatment liquid into a container with a plurality of layers of photocatalytic plates arranged inside, and irradiating ultraviolet light in the container for a certain time to obtain degraded wastewater;

the surface of the photocatalytic plate contains a certain amount of metallic silver and rare earth elements.

The method for degrading the organic dye in the wastewater firstly introduces a certain amount of hydrogen peroxide into the wastewater, so that the organic dye in the wastewater is firstly oxidized to be nextUltraviolet light is degraded to form reaction sites, and meanwhile, oxygen is formed after decomposition of hydrogen peroxide, so that the oxygen content in the solution is greatly improved. Meanwhile, oxygen can be uniformly mixed with acetaldehyde for photocatalysis, and the acetaldehyde in the wastewater reacts with a photocatalytic plate under the action of ultraviolet light to generate HO_xThe free radical can be used as a catalytic promoter to generate free radical oxidation reaction with the organic dye in the wastewater, so that the organic dye can be degraded under the condition of low optical density, and the decomposition efficiency of the organic dye can be effectively improved by matching with the oxidation of oxygen. In addition, because the surface of the photocatalytic plate contains a certain amount of metal silver and rare earth elements, the photocatalytic plate has good photosensitive activity and photosensitive excitability, so that the photocatalytic reaction activity can be greatly enhanced, and the photocatalytic effect is greatly improved.

Preferably, the adding amount of the hydrogen peroxide in the step (1) is 0.001 ~ 0.05.05 percent of the mass of the wastewater.

Preferably, the acetaldehyde content in step (2) is 300 ~ 1500ppm to 1500 ppm.

The acetaldehyde addition amount concentration is ppm level, the decomposition efficiency of the organic dye can be effectively improved under the concentration, and the acetaldehyde can effectively and completely form HO under the concentration_xFree radicals, which prevent acetaldehyde from still being present in the wastewater after photodegradation.

Preferably, the preparation method of the photocatalytic plate in the step (3) is as follows:

(S.1) preparing the rare earth-containing aerogel: stirring and mixing tetraethoxysilane, rare earth powder, an acid catalyst and an absolute ethyl alcohol solvent, standing, heating and aging to obtain wet sol, and performing supercritical treatment to obtain rare earth aerogel;

(S.2) depositing metallic silver on the surface: crushing the rare earth aerogel, adding the crushed rare earth aerogel into a silver ammonia solution, uniformly mixing, then dripping a glucose solution into the mixture, stirring the mixture in a water bath for a certain time, and filtering and drying the mixture to obtain rare earth aerogel powder with metal silver deposited on the surface;

(S.3) sintering and forming: the rare earth aerogel powder with the surface deposited with the metal silver is subjected to uniaxial compression to obtain a slab, and then the slab is sintered at high temperature to obtain the photocatalytic plate.

According to the invention, tetraethoxysilane is used as a carrier to adsorb rare earth powder to generate aerogel containing rare earth components, the aerogel is crushed and dissolved in silver ammonia solution, and metallic silver is precipitated on the surface of the rare earth aerogel powder by adding acetaldehyde solution. Then the rare earth aerogel powder with metal silver deposited on the surface is sintered to obtain the photocatalytic plate with more pores, so that the wastewater can be catalyzed on the surface of the photocatalytic plate and can enter the pores inside the photocatalytic plate for catalysis, and the catalytic effect is improved.

Preferably, the mass ratio of the tetraethoxysilane to the rare earth powder in the step (S.1) is 100 (1 ~ 5), the pH of the solution is adjusted to 2 ~ 3.5.5 by the acid catalyst, and the reaction is stirred for 20 ~ 40 min.

Preferably, the rare earth powder of step (s.1) includes, in parts by weight, cerium oxide 20 ~ 35 parts, europium oxide 10 ~ 15 parts, lanthanum oxide 10 ~ 15 parts, and ytterbium oxide 3 ~ 8 parts.

Preferably, the aging temperature in the step (S.1) is 65 ~ 75 ℃, the aging time is 1 ~ 3h, the supercritical temperature is 250 ~ 280 ℃, and the supercritical pressure is 5 ~ 8 MPa.

Preferably, in the step (S.2), the mass ratio of the rare earth aerogel to the silver ammonia solution is (10 ~ 35): 100, the mass fraction of the glucose solution is 20 ~ 30%, the volume ratio of the silver ammonia solution to the glucose solution is 100: (0.2 ~ 0.5), and the water bath temperature is 60 ~ 65 ℃.

Preferably, in the step (s.3), the uniaxial compression pressure is 8 ~ 12MPa, the sintering temperature is 600 ~ 850 ℃, and the sintering atmosphere is nitrogen.

Preferably, the ultraviolet light emission wavelength in the step (3) is 254nm, and the irradiation intensity is 120 ~ 150uW/cm²The irradiation time was 10 ~ 30 min.

Therefore, the invention has the following beneficial effects:

(1) the organic dye in water can be rapidly degraded under the condition of low ultraviolet intensity;

(2) the addition content of the photocatalytic promoter is low;

(3) the photocatalytic efficiency does not decrease with time.

Drawings

FIG. 1 is a graph showing organic dye concentration time curves of example 1 and comparative examples 1 and 2.

Detailed Description

The invention is further described with reference to the drawings and the specific embodiments. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.