Catalyst for treating pharmaceutical wastewater as well as preparation method and application of catalyst

Abstract

The invention belongs to the technical field of pharmaceutical wastewater treatment, and particularly discloses a catalyst for treating pharmaceutical wastewater and a preparation method and application thereof.The catalyst can rapidly degrade pollutants and is high in sewage treatment efficiency, good in chemical stability, non-toxic and odorless, meanwhile, in the preparation process of the catalyst, raw materials are rich in source, the preparation and forming process is simple, and the catalyst is suitable for industrial production. Large-scale industrial production can be realized; when the catalyst is coated on a porous ceramic or activated carbon filter screen for pharmaceutical sewage treatment, the catalyst can be recycled, secondary pollution hidden dangers are avoided, the water purification rate is greatly improved, and the pharmaceutical sewage treatment cost is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of pharmaceutical wastewater treatment, and specifically relates to a catalyst for treating pharmaceutical wastewater and a preparation method and application thereof. Background Art

[0004] Pharmaceutical industrial wastewater not only contains a large amount of heavy metals and harmful chemicals, but also contains non-degradable pollutants, plus various acids, alkalis, tannins and anthraquinone components. If the treatment is not up to standard, it will bring many negative impacts to the environment and restrict the sustainable development of the pharmaceutical industry. With the development of the pharmaceutical industry, pharmaceutical wastewater has become an increasingly important source of pollution. Due to the complex composition of pharmaceutical wastewater, high organic content, high toxicity, dark color, high salt content, especially the lack of biochemical characteristics and intermittent discharge, it is difficult to treat. Antibiotic residues and high levels of organic matter in wastewater make it difficult for traditional biological treatment to achieve ideal treatment effects. Due to the strong inhibitory effect of residual antibiotics on microorganisms, aerobic bacteria are poisoned and aerobic treatment becomes difficult. Organic matter is difficult to meet the drainage standards and needs further treatment. The complexity of pharmaceutical wastewater and the high consumption, low efficiency and difficulty of traditional biochemical treatment processes are the direct reasons why many pharmaceutical factories directly discharge a large amount of pharmaceutical wastewater.

[0005] Pharmaceutical wastewater has a complex composition and contains a large number of organic pollutants, antibiotics, co-precipitates and other harmful substances. Silver phosphate (Ag3PO4) is a photocatalyst that exhibits excellent degradation of organic pollutants. The unique energy band position of Ag3PO4 enables the photogenerated holes in its valence band to have strong oxidation ability, which can directly oxidize and degrade pollutants. However, the photocatalytic efficiency of Ag3PO4 monomer needs to be further improved. In addition, its photocorrosion is relatively serious, which seriously hinders its promotion and application. The fundamental reason for photocorrosion is that the recombination process of photogenerated electron-hole pairs is much faster than the capture-transfer process, which makes Ag3PO4 + It is reduced to silver by photogenerated electrons, which destroys the crystal structure of Ag3PO4 and reduces the light absorption performance, thereby reducing the photocatalytic activity and the reusability, which seriously hinders its promotion and application.

[0006] At present, modifying the structure and properties of silver phosphate by adding modifiers is an effective way to achieve photogenerated carrier separation. However, the existing modified silver phosphate catalysts still have the disadvantages of low separation efficiency of photogenerated electron-hole pairs, weak photocorrosion resistance, and weak photocatalytic activity, resulting in the catalyst being unable to meet the requirements of efficient degradation and removal of organic pollutants, thus greatly limiting the promotion and application of existing silver phosphate composite photocatalysts. Summary of the invention

[0007] In order to solve the above technical problems, the present invention proposes a catalyst for treating pharmaceutical wastewater and its preparation method and application, which can quickly degrade pollutants, has high efficiency and good chemical stability, is non-toxic and odorless, has abundant raw material sources, and has a simple preparation and molding process, and can realize large-scale industrial production.

[0008] In order to achieve the above object, the present invention is achieved through the following technical solutions:

[0009] The invention provides a catalyst for treating pharmaceutical wastewater. The catalyst comprises a nano-substrate Ag3PO4 and illite / montmorillonite mixed-layer clay supported on the substrate.

[0010] Preferably, the illite / montmorillonite mixed layer clay is doped with metal ions for modification.

[0011] The present invention also provides a method for preparing the above catalyst, the specific steps are as follows:

[0012] S1: Preparation of nano-substrate Ag3PO4: In the absence of light, add AgNO3 to deionized water and stir vigorously to obtain solvent A, then dissolve Na2HPO4 and PVP in deionized water and stir to obtain reagent B; then drop reagent B into reagent A to obtain a bright yellow precipitate, then repeatedly wash and centrifuge, and dry to obtain nano-substrate Ag3PO4;

[0013] S2: Prepare a composite catalyst by loading modified illitium / montmorillonite mixed layer clay on the nano-substrate Ag3PO4: Add Ag3PO4 into ethanol and stir to disperse it, and then drop the illitium / montmorillonite mixed layer clay suspension into it. After stirring and mixing, fully precipitate it, and then dry, calcine and polymerize it to obtain a composite catalyst.

[0014] Preferably, in the S2, Ag3PO4 is added to ethanol and stirred to disperse, and an illite / montmorillonite mixed layer clay suspension is added dropwise, stirred and mixed, and then fully precipitated and placed in a vacuum oven at 80°C for drying for 24 hours, and then heated to 550°C in a muffle furnace at a heating rate of 2°C / min and calcined for 2 hours to obtain a composite catalyst.

[0015] The present invention also provides the use of the above catalyst in treating pharmaceutical wastewater:

[0016] The catalyst is coated on a porous ceramic or activated carbon filter. The illite / montmorillonite mixed layer clay and activated carbon adsorb harmful substances, while Ag3PO4, under the action of light, will generate oxygen free radicals and superoxide free radicals, which will decompose organic pollutants and bacteria into carbon dioxide and water, thereby achieving the degradation of pharmaceutical wastewater.

[0017] The beneficial effects of the present invention are:

[0018] The catalyst of the present invention can quickly degrade pollutants, has high sewage treatment efficiency, good chemical stability, and is non-toxic and tasteless. At the same time, in the preparation of the catalyst, the source of raw materials is abundant, the preparation and molding process is simple, and large-scale industrial production can be achieved; and when the catalyst is coated on a porous ceramic or an activated carbon filter for treating pharmaceutical sewage, it can be recycled without the risk of secondary pollution, greatly improving the water purification rate and greatly reducing the treatment cost of pharmaceutical sewage. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0020] Example 1

[0021] A catalyst for treating pharmaceutical wastewater comprises a nano-substrate Ag3PO4 and illitium / montmorillonite mixed-layer clay loaded on the substrate; the illitium / montmorillonite mixed-layer clay is doped with silver ions for modification.

[0022] The preparation method of the above catalyst comprises the following specific steps:

[0023] S1: Preparation of nano-substrate Ag3PO4: In the absence of light, add 0.51g AgNO3 to 60ml deionized water and stir magnetically for 20min to obtain solvent A; take 0.358g Na2HPO4 and 0.1g PVP and dissolve them in 20ml deionized water respectively, stir for 20min to obtain reagent B; then, slowly drip reagent B into reagent A, and observe bright yellow precipitate, which is Ag3PO4; after the precipitate is left to stand for a period of time, it is repeatedly washed with anhydrous ethanol and deionized water, centrifuged, and then placed in a 60℃ oven to dry for 8 hours to obtain a yellow Ag3PO4 photocatalyst;

[0024] S2: Prepare a composite catalyst by loading modified illitium / montmorillonite mixed layer clay on the nano-substrate Ag3PO4: Add 0.300g Ag3PO4 to 50mL ethanol and stir for 30min to make it evenly dispersed. Then, under stirring, add the illitium / montmorillonite mixed layer clay suspension to the above solution, continue stirring for 5h after the addition is complete, let it stand for 12h to allow the precipitation to be complete, put it in a vacuum oven at 80℃ to dry for 24h, and finally heat it to 550℃ in a muffle furnace at a heating rate of 2℃ / min and calcine for 2h to obtain a composite catalyst.

[0025] Example 2

[0026] The laboratory used antibiotics to simulate organic wastewater to test the catalyst prepared in Example 1:

[0027] A 10mg / CIP (antibiotic) solution was prepared in a 1L volumetric flask to simulate the organic wastewater of a pharmaceutical factory. 50mg of the catalyst was dispersed in 100mL of the CIP solution. The mixed solution was stirred in the dark for at least 30min to ensure that the photocatalyst and CIP reached the state of adsorption-desorption equilibrium. A xenon lamp equipped with a 420nm filter was used to simulate the light source. The photocatalytic reaction was carried out under uniform stirring. The illumination time was 1.5h. 5mL of the suspension was extracted every 15min and centrifuged. After centrifugation at a speed of 8000r / min for 3min, the supernatant was separated and analyzed by a UV-visible spectrophotometer to determine the CIP concentration.

[0028] In order to more accurately test the photocatalytic performance of the catalyst, tetracycline and sulfamethoxazole were used as target pollutants in this experiment. The main physicochemical parameters of the three antibiotics are shown in Table 1, and photocatalytic degradation was performed on them. The experimental steps are the same as those described for the determination of CIP. First, a 10 mg / L target pollutant solution was prepared, and then 50 mg of the photocatalyst was weighed and placed in 100 mL of the target pollutant solution. After stirring and dispersing the dark reaction for 30 minutes, the photocatalytic reaction was carried out under visible light irradiation for 1.5 hours. The reaction process is the same.

[0029] Table 1 Main physicochemical parameters of three antibiotics

[0030] Name / Nature Ciprofloxacin Sulfamethoxazole tetracycline Molecular formula <h2 style=";text-align:left;direction:ltr"><![CDATA[C <h2 style=";text-align:left;direction:ltr"> 17 <h2 style=";text-align:left;direction:ltr"> H<h2 style=";text-align:left;direction:ltr"> 18 <h2 style=";text-align:left;direction:ltr"> FN3O3<h2 style=";text-align:left;direction:ltr"> <![CDATA[C 10 H 11 N303S]]> <![CDATA[C 22 H 24 N2O8]]> Water solubility (mg / L) 11480 3942 3877 Log Kow 0.28 0.89 -1.3 Log Koa 16.962 11.298 20.42 Log BCF 0.5 0.5 0.5

[0031] The test results are shown in Table 2.

[0032] Table 2 Changes in concentration ratio and time after photocatalytic degradation of three antibiotics

[0033] Name / Concentration Ratio / Time 0min 15min 30min 45min 60min 75min 90min Ciprofloxacin 1 0.96 0.91 0.53 0.29 0.23 0.14 Sulfamethoxazole 1 0.82 0.45 0.33 0.26 0.16 0.12 tetracycline 1 0.95 0.89 0.56 0.32 0.24 0.15

[0034] From the test results, it can be seen that the photocatalytic removal efficiency of the catalyst for the three target pollutants is as high as over 80%. Therefore, the photocatalytic performance of the catalyst is very good and it has high photocatalytic activity for a variety of pollutants.

[0035] Example 3

[0036] The catalyst prepared in Example 1 was used to test actual pharmaceutical organic wastewater:

[0037] The catalyst is coated on a porous ceramic or activated carbon filter and applied to sewage treatment. After filtering large and small particles in the sewage in advance, the heavy metals are directly adsorbed and organic and inorganic pollutants are degraded. The filter is used in the treatment of pharmaceutical wastewater circulation to degrade E. coli and organic pollutants in the water.

[0038] The test process and results are shown in Table 3.

[0039] Table 3 Test methods and results of different types of pharmaceutical wastewater

[0040]

[0041] In summary, the composite catalyst has good degradation efficiency for various pharmaceutical wastewaters.

[0042] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the invention to only the specific embodiments described. Obviously, many modifications and changes can be made according to the content of this specification.

Claims

1. A catalyst for treating pharmaceutical wastewater, characterized in that: The catalyst comprises nano-substrate Ag3PO4 and illite / montmorillonite mixed layer clay supported on the substrate.

2. The catalyst for treating pharmaceutical wastewater according to claim 1, characterized in that: The illite / montmorillonite mixed layer clay is doped with metal ions for modification.

3. The method for preparing a catalyst for treating pharmaceutical wastewater according to any one of claims 1 to 2, characterized in that: The following steps are involved: S1: Preparation of nano-substrate Ag3PO4: In the absence of light, add AgNO3 to deionized water and stir vigorously to obtain solvent A, then dissolve Na2HPO4 and PVP in deionized water and stir to obtain reagent B; then drop reagent B into reagent A to obtain a bright yellow precipitate, then repeatedly wash and centrifuge, and dry to obtain nano-substrate Ag3PO4; S2: Prepare a composite catalyst by loading modified illitium / montmorillonite mixed layer clay on the nano-substrate Ag3PO4: Add Ag3PO4 into ethanol and stir to disperse it, and then drop the illitium / montmorillonite mixed layer clay suspension into it. After stirring and mixing, fully precipitate it, and then dry, calcine and polymerize it to obtain a composite catalyst.

4. The method for preparing a catalyst for treating pharmaceutical wastewater according to claim 3, characterized in that: In the S2, Ag3PO4 is added to ethanol and stirred to disperse, and the illite / montmorillonite mixed layer clay suspension is added dropwise. After stirring and mixing, the mixture is fully precipitated and then placed in a vacuum oven at 80°C for drying for 24 hours. The mixture is then heated to 550°C in a muffle furnace at a heating rate of 2°C / min and calcined for 2 hours to obtain a composite catalyst.

5. Application of the catalyst for treating pharmaceutical wastewater according to claim 1 in treating pharmaceutical wastewater: the catalyst is coated on a porous ceramic or activated carbon filter, the illite / montmorillonite mixed layer clay and activated carbon adsorb harmful substances, and Ag3PO4, under the action of light, will generate oxygen free radicals and superoxide free radicals, which will decompose organic pollutants and bacteria into carbon dioxide and water, thereby achieving the degradation of pharmaceutical wastewater.

Images