CN115367844B - Method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and hierarchical crystallization - Google Patents

Method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and hierarchical crystallization Download PDF

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CN115367844B
CN115367844B CN202211111137.5A CN202211111137A CN115367844B CN 115367844 B CN115367844 B CN 115367844B CN 202211111137 A CN202211111137 A CN 202211111137A CN 115367844 B CN115367844 B CN 115367844B
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containing wastewater
wastewater
organic salt
crystallization
organic
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CN115367844A (en
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瞿广飞
李应丽
李志顺成
潘科衡
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Kunming University of Science and Technology
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/467—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction
    • C02F1/4672—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis by electrochemical disinfection; by electrooxydation or by electroreduction by electrooxydation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D9/00—Crystallisation
    • B01D9/02—Crystallisation from solutions
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/50—Carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/24—Sulfates of ammonium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/04—Chlorides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D3/00—Halides of sodium, potassium or alkali metals in general
    • C01D3/22—Preparation in the form of granules, pieces, or other shaped products
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/46—Sulfates
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/30—Treatment of water, waste water, or sewage by irradiation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/50—Processes
    • C25B1/55—Photoelectrolysis
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46119—Cleaning the electrodes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
    • C02F1/46104—Devices therefor; Their operating or servicing
    • C02F1/46109—Electrodes
    • C02F2001/46133—Electrodes characterised by the material
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy

Abstract

The invention discloses a method for purifying organic salt-containing wastewater by electrocatalytic oxidation and cooperative fractional crystallization recycling, which comprises the steps of introducing the organic salt-containing wastewater into a photoelectrocatalytic oxidation device, under the aeration condition, decomposing substances which are difficult to degrade in the organic salt-containing wastewater into micromolecular organic carbon sources under the action of electric field coupling self-luminous photoelectrocatalysis, and catalyzing to generate OH and O 3 Conversion of organic material to CO 2 And H 2 O, the self-cleaning luminous photoelectrocatalysis electrode group in the electrolytic tank improves the catalytic reaction performance of the electrolytic tank, SO that the sulfur salt and sulfurous acid in the organic salt-containing wastewater are fully oxidized into SO 4 2‑ After the degradation of organic matters in the organic salt-containing wastewater is completed, the wastewater contains SO 4 2‑ The waste water of metal cation enters the fractional crystallization device through the ultrasonic descaling anti-blocking device, different crystallization agents are added, calcium sulfate, ammonium sulfate and sodium chloride crystals are respectively separated out, and the device can effectively realize the recycling of resources and the purification treatment of waste water.

Description

Method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and hierarchical crystallization
Technical Field
The invention relates to the field of high-salt wastewater treatment, in particular to a process for purifying organic salt wastewater by photoelectrocatalytic oxidation and hierarchical crystallization.
Background
The organic high-salt-content wastewater refers to wastewater with the total salt content of at least 1 percent, and is mainly from chemical plants, oil and gas collection and processing and the like. Such waste water contains a variety of substances including salts, oils, organic heavy metals and radioactive substances. The industrial wastewater mainly contains organic matters and inorganic salts 2, has complex composition components including K + 、Ca 2+ 、Na + 、Mg 2+ 、CO 3 2- 、NO 3 2- 、Cl - 、SO 4 2- Plasma, wherein Na + 、Cl - 、SO 4 2- The ions account for more than 90% of the total inorganic salt ions and are far higher than other ions. The high-salt wastewater has great influence on production, life and environment: (1) land salinization, soil hardening and fertility reduction are not beneficial to nutrient absorption of crops and growth inhibition of crops; (2) the water body is polluted by untreated discharge of high-concentration organic matters into the water body, so that the nutrition degree of the water body is increased; (3) contains pungent odor, is discharged into the atmosphere untreated, pollutes the atmosphere quality, and affects the human respiratory tract health; (4) some high-salt wastewater is in an acidic state; untreated water is discharged to the water body, so that the water quality is acidified, and the growth of aquatic organisms is influenced. Therefore, finding a more economical and efficient high-salt wastewater treatment technology becomes a serious problem in the field of wastewater treatment, and is also a problem to be solved in the continuous and healthy development of society.
At present, the research on organic high-salt wastewater mostly aims at removing impurities to achieve the purpose of purifying water, and has the advantages of complex flow, uncontrollable effect and higher cost in the aspect of comprehensive utilization. CN202023248883.8 provides a zero-emission pretreatment system for salt-containing wastewater and a zero-emission wastewater treatment system, mainly using two precipitation devices, achieving the effect of reducing hardness, alkalinity and silicon content of the salt-containing wastewater; CN201010111515.0 provides a method for treating high-salt wastewater, which improves water recovery rate by filtering high-salt wastewater by using a sodium ion exchanger, using a weak acid ion exchanger, a reverse osmosis device, and the like; CN201610903945.3 provides a method for treating salt-containing waste water and a production process for preparing sodium chloride, ammonium sulfate and compound fertilizer from the salt-containing waste water, the salt-containing waste water is sent into a flue gas purifying system as a supplementary solution after COD is removed to react with raw flue gas to obtain purified flue gas and washing slurry for treatment, and the purified flue gas and washing slurry can be treated on the basis of the COD by a separating system comprising a double decomposition reactor, an evaporating system and/or a nanofiltration membrane, etc., so that the waste water treatment is completed and the ammonium sulfate, compound fertilizer and/or sodium chloride and sodium bicarbonate products are obtained. The method achieves the purpose of recycling the wastewater, but has the advantages of more equipment, complex operation and maintenance, higher production and operation cost and limited economic value. So the method and the equipment for economically and efficiently producing the organic high-salt wastewater are continued.
Disclosure of Invention
The invention provides a method for purifying organic salt-containing wastewater by combining photoelectrocatalytic oxidation with fractional crystallization to recycle, which comprises the steps of introducing the organic salt-containing wastewater into a photoelectrocatalytic oxidation device, wherein the photoelectrocatalytic oxidation device comprises an open shell, more than one anode electrode plate and more than one cathode electrode plate are alternately arranged in the shell to form more than one self-cleaning luminous photoelectrocatalytic electrode group connected with a power supply, under the aeration condition, substances which are difficult to degrade in the organic salt-containing wastewater are decomposed into small molecular organic carbon sources under the action of electric field coupling self-luminous photoelectrocatalysis, and the OH and O generated by the catalysis effect 3 Conversion of organic material to CO 2 And H 2 O, the self-cleaning luminous photoelectrocatalysis electrode group in the electrolytic tank improves the catalytic reaction performance of the electrolytic tank, SO that the sulfur salt and sulfurous acid in the organic salt-containing wastewater are fully oxidized into SO 4 2- After the degradation of organic matters in the organic salt-containing wastewater is completed, the wastewater contains SO 4 2- The waste water of metal cations enters a fractional crystallization device through an ultrasonic descaling anti-blocking device, different crystallization agents are added, calcium sulfate, ammonium sulfate and sodium chloride crystals are respectively separated out, and the waste water reaching the discharge standard is discharged from a water outlet.
The anode plate is a self-cleaning luminous photoelectric synergistic catalytic electrode (prepared by the method in application number 202210313504.3), and the cathode plate is a plate-shaped baseThe electrode with a hole transmission layer covered on one surface of the bottom and a piezoelectric layer covered on the other surface is made of manganese oxide, the piezoelectric layer is made of piezoelectric particles and piezoelectric polymers, the piezoelectric particles are formed by mixing more than 2 of zinc oxide, aluminum oxide and silicon dioxide, the piezoelectric polymers are PVDF, the substrate is platinum, titanium, zirconium or ruthenium, the power supply is alternating current or pulse electricity, and the current density is 15-30 mA/cm 2 。
The aeration medium is oxygen, air or ozone.
The ultrasonic descaling anti-blocking device is a pipeline with a plurality of ultrasonic transducers, the amplitude of the ultrasonic transducers is 10-60 mu m, and the ultrasonic frequency is 40-80 kHz.
The said composition contains SO 4 2- Adding dilute sulfuric acid to adjust the pH of the wastewater to 3-5 after the wastewater containing metal cations enters a fractional crystallization device, precipitating calcium sulfate, filtering and collecting calcium sulfate, adding concentrated ammonia water into filtrate to adjust the pH to 5-9, adding a crystallization agent, precipitating ammonium sulfate crystals at the temperature of 25-55 ℃ and the stirring intensity of 550-800 r/min, filtering and collecting ammonium sulfate, adding a crystallization inhibitor into the filtrate, filtering, and concentrating the filtrate to obtain sodium chloride crystals; or ammonium sulfate crystal is separated out firstly, and then calcium sulfate and sodium chloride are separated out in sequence.
The crystallization agent is dimethyl sulfoxide, absolute methanol or absolute ethanol, the addition amount is 300-500 mL of the filtrate per 1L, the crystallization inhibitor is polycarboxylate, propylene glycol block polyether or polyether type nonionic surfactant, and the addition amount is 40-150 g of the filtrate per 1L.
The beneficial results of the invention are as follows: compared with the traditional organic high-salt wastewater treatment process, the process adopts the photoelectrocatalysis oxidation technology, and the OH and O generated by the photocatalysis effect of the surface of the self-cleaning luminous electrode plate 3 Conversion of organic material to CO 2 And H 2 O, can get rid of the organic pollutant in the waste water fast, and the electrode plate accessible alternating current or the pulse electricity of certain frequency produce normal position micro-vibration, makes the pollutant that adheres to the electrode surface drop from the electrode surface and realizes self-cleaning, has greatly alleviateed operating pressure and cost. In addition, in the fractional crystallization control device, different control methods are adoptedThe operating conditions of (2) can selectively fractional crystallize calcium sulfate, ammonium sulfate and sodium chloride.
Drawings
FIG. 1 is a schematic diagram of the structure of the device of the present invention;
in the figure: 1-a water inlet I; 2-a photoelectrocatalytic oxidation device; 3-power supply; 4-a positive electrode plate; 5-a cathode plate; a 6-COD sensor; 7-a microporous aerator; 8-crystal mud storage tanks; 9-exhaust fan; 10-an air filter; 11-a water outlet; 12-ultrasonic descaling and blocking preventing device; 13-water inlet II; 14-fractional crystallization device; 15-a stirrer; 16-mud discharging port.
Detailed Description
The present invention will be described in further detail with reference to examples, but the scope of the present invention is not limited to the above description; the device used in the following embodiment comprises a photoelectrocatalysis oxidation device 2, a power supply 3, an ultrasonic descaling anti-blocking device 12, a fractional crystallization device 14 and a crystal mud storage tank 8, wherein the photoelectrocatalysis oxidation device 2 comprises an open shell, 3 anode plates 4 and 3 cathode plates 5 are alternately placed in the shell to form 3 groups of self-cleaning luminous photoelectrocatalysis electrode groups, the anode plates 4 and the cathode plates are respectively connected with the power supply 3, a water inlet I1 and a water outlet 11 are arranged on the shell, a microporous aerator 7 is arranged at the bottom of the shell, the microporous aerator 7 is connected with an air filter 10 through an exhaust fan 9, the air filter is connected with an air source, the water outlet 11 is connected with a water inlet II 13 at the lower part of the fractional crystallization device 14 through the ultrasonic descaling anti-blocking device 12, a stirrer 15 is arranged in the fractional crystallization device, a mud discharge port 16 connected with the crystal mud storage tank 8 is arranged at the bottom of the fractional crystallization device, and a COD sensor 6 (figure 1) is arranged in the photoelectrocatalysis oxidation device.
Example 1
The device is used for treating the fermentation industrial high-salt-content wastewater of a petrochemical enterprise, wherein the COD concentration in the wastewater is 3000 mg/L-6000 mg/L, the sulfate concentration is 20000 mg/L-25000 mg/L, and the Na concentration is 3000mg/L + The concentration is 300-400 mg/L, ca 2+ The concentration is 200 mg/L-300 mg/L, mg 2+ The concentration is 100-150 mg/L, cl - 500 to 600mg/L, and organic matters such as polycyclic aromatic hydrocarbon compounds, aromatic amine compounds and heterocyclic compounds.
The anode plate in this example was prepared by the method of example 1 in 202210313504.3, wherein one surface of the substrate of the anode was covered with a hole transport layer, the other surface was covered with a piezoelectric layer, a quantum dot layer was provided on the hole transport layer, and a catalytic material layer was provided on the quantum dot layer; titanium is used as a substrate, cuSCN is used as a hole transport layer material, alNP is used as a quantum dot layer material, iridium-iron alloy is used as a catalytic material layer, and PVDF and BiFeO are used as catalyst materials 3 The ceramic is a piezoelectric layer material;
the cathode plate is an electrode with one surface covered with a hole transport layer and the other surface covered with a piezoelectric layer, the hole transport layer is made of manganese oxide, and the piezoelectric layer is made of piezoelectric particles and piezoelectric polymers; specifically, polishing and grinding a platinum-based metal sheet by using sand paper, soaking in a mixed solution of nitric acid, hydrofluoric acid and water (volume ratio is 3:1:3) for 30 seconds, and ultrasonically cleaning by using deionized water; heating a substrate metal sheet at 60 ℃, blowing and spraying 0.1mol/L manganese oxide ethanol solution onto one surface of a substrate through nitrogen, and circulating for 8 times to form a hole transport layer; znO and Al 2 O 3 Mixing and drying (mass ratio of 1:1), ball milling, sieving, placing into a crucible, preserving heat at 740 ℃ for 4 hours, cooling, ball milling to obtain piezoelectric particles, stirring PVDF, PVP and NMP (mass ratio of 10:1:60) at 40 ℃ for 3 hours to obtain membrane base solution, adding the piezoelectric particles into the membrane base solution according to the additive amount of 5%, continuously stirring for 6 hours, casting the slurry into a membrane, soaking in distilled water for 12 hours, and carrying out polarization treatment with the polarization voltage of 24kV for 15 minutes; and (3) adhering the film to the other surface of the substrate after film formation to prepare the cathode plate.
Filtering the salt-containing wastewater, then introducing the filtered salt-containing wastewater into a photoelectrocatalysis oxidation device 2 through a water inlet I, applying alternating current to a positive electrode plate and a negative electrode plate in the photoelectrocatalysis oxidation device 2, and controlling the current density of the alternating current to be 15.2mA/cm 2 Introducing air into the microporous aerator 7 through the exhaust fan 9, treating the wastewater under aeration, wherein the removal rate of organic matters such as polycyclic aromatic hydrocarbon compounds, aromatic amine compounds and heterocyclic compounds reaches 82% after 30min, and when the detection data of the COD sensor shows that the total organic pollutant amount is less than 35mg/L, the wastewater contains SO 4 2- 、Cl - And metal cations from the water outlet 11 through the water outlet with severalThe ultrasonic energy converter (ultrasonic frequency 40 kHz) pipeline enters the fractional crystallization device 14, 70% sulfuric acid solution is added into the wastewater, the pH of the wastewater is regulated to 3, stirring is carried out for 10min, calcium sulfate salt is separated out, crystals are collected from a sludge outlet at the bottom of the device to obtain calcium sulfate with purity of more than 85% (liquid in the collecting process is returned to the fractional crystallization device), then 25% concentrated ammonia water is added into the wastewater, the pH is regulated to 6, crystals are separated out according to the proportion of 400mL of anhydrous methanol added into each liter of wastewater, after the anhydrous methanol is added, stirring is carried out for 15min at 30 ℃ and 600r/min, ammonium sulfate crystals with purity of more than 94% are collected from a sludge outlet at the bottom of the device, finally polycarboxylate is added into the wastewater according to the proportion of 50g of polycarboxylate added into each liter of water, filtering is carried out after stirring, the filtrate is concentrated to obtain sodium chloride crystals with purity of more than 98%, and redundant liquid in the process of collecting crystals is returned to the fractional crystallization device.
Example 2
The anode plate in this example was prepared by the method of example 1 in 202210313504.3, wherein one surface of the substrate of the anode was covered with a hole transport layer, the other surface was covered with a piezoelectric layer, a quantum dot layer was provided on the hole transport layer, and a catalytic material layer was provided on the quantum dot layer; specifically, ruthenium is used as a substrate, cu 2 O is a material of a hole transport layer, alNP is a material of a quantum dot layer, zirconium-iron alloy is a catalytic material layer, and PVDF and lithium manganate are piezoelectric layer materials;
the cathode plate is prepared by polishing and grinding a titanium substrate metal sheet by using sand paper, soaking the titanium substrate metal sheet in a mixed solution of nitric acid, hydrofluoric acid and water (volume ratio is 3:1:3) for 30s, and ultrasonically cleaning the titanium substrate metal sheet by using deionized water; heating a substrate metal sheet at 60 ℃, blowing and spraying 0.1mol/L manganese oxide ethanol solution onto one surface of a substrate through nitrogen, and circulating for 8 times to form a hole transport layer; znO and Al 2 O 3、 SiO 2 (1:1:1) mixing, drying, ball milling, sieving, placing into a crucible, preserving heat at 740 ℃ for 4 hours, cooling, ball milling to obtain piezoelectric particles, stirring PVDF, PVP and NMP (10:1:60) at 45 ℃ for 3 hours to obtain membrane base solution, adding the piezoelectric particles into the membrane base solution according to the addition amount of 5%, continuously stirring for 6 hours, casting the slurry into a membrane, soaking in distilled water for 12 hours, and carrying out polarization treatment with the polarization voltage of 24kV for 15 minutes; post film formation adhesiveAttaching to the other surface of the substrate to obtain a cathode plate;
the device is used for treating the ammonia desulfurization salt-containing wastewater of a coking enterprise, wherein the COD concentration in the wastewater is 5000mg/L to 8000mg/L, the ammonia nitrogen concentration is 2000mg/L to 3000mg/L, and the Cl concentration is 2000mg/L - The concentration is 300-500 mg/L, the concentration of thiocyanide is 350-500 mg/L, fe 3+ The concentration is 1000mg/L to 2000mg/L, and the like, and organic pollutants such as phenol, quinoline, organic nitrile and the like are also contained.
Filtering the salt-containing wastewater, then introducing the filtered salt-containing wastewater into a photoelectrocatalysis oxidation device 2 through a water inlet I, applying alternating current to a positive electrode plate and a negative electrode plate in the photoelectrocatalysis oxidation device 2, and ensuring that the alternating current density is 20mA/cm 2 Introducing air into the microporous aerator 7 through the exhaust fan 9, treating the wastewater under aeration, wherein the removal rate of phenol, quinoline and organic nitrile reaches 85% after 30min, and when the detection data of the COD sensor show that the total organic pollutant amount is less than 35mg/L, the wastewater contains SO 4 2- 、Cl - And the waste water of metal cations enters a fractional crystallization device 14 from a water outlet 11 through a pipeline with a plurality of ultrasonic transducers (ultrasonic frequency is 50 kHz), the pH value of the solution is regulated to 8, the solution is stirred for 15min at 25 ℃ and 700r/min after the absolute ethyl alcohol is added according to the proportion of adding 350mL absolute ethyl alcohol into each liter of waste water, crystals are separated out, ammonium sulfate crystals with purity of more than 95% are collected from a mud outlet at the bottom of the device, 70% sulfuric acid solution is added into the residual solution, the pH value of the waste water is regulated to 5, stirring is carried out for 10min, calcium sulfate salt is separated out, crystals are collected from a mud outlet at the bottom of the device, calcium sulfate with purity of more than 85% is obtained, finally polycarboxylate is added into the waste water according to the proportion of adding 45g of polycarboxylate into each liter of water, stirring is carried out, and the filtrate is concentrated to obtain sodium chloride crystals with purity of more than 98%.

Claims (3)

1. A method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and cooperative fractional crystallization is characterized by comprising the following steps: introducing organic salt-containing wastewater into a photoelectrocatalytic oxidation device, wherein the photoelectrocatalytic oxidation device comprises an open shell, more than one anode electrode plates and more than one cathode electrode plates which are alternately arranged in the shell to form more than one self-cleaning luminous photoelectrocatalytic electrode group connected with a power supply, and aeratingUnder the condition, substances which are difficult to degrade in organic salt-containing wastewater are decomposed into micromolecular organic carbon sources under the action of self-luminous photoelectrocatalysis of electric field coupling, and OH and O generated by catalysis 3 Conversion of organic material to CO 2 And H 2 O, the self-cleaning luminous photoelectrocatalysis electrode group in the electrolytic tank improves the catalytic reaction performance of the electrolytic tank, SO that the sulfur salt and sulfurous acid in the organic salt-containing wastewater are fully oxidized into SO 4 2- After the degradation of organic matters in the organic salt-containing wastewater is completed, the wastewater contains SO 4 2- The waste water of metal cations enters a fractional crystallization device through an ultrasonic descaling anti-blocking device, different crystallization agents are added, calcium sulfate, ammonium sulfate and sodium chloride crystals are respectively separated out, and the waste water reaching the discharge standard is discharged from a water outlet;
containing SO 4 2- Adding dilute sulfuric acid to adjust the pH of the wastewater to 3-5 after the wastewater containing metal cations enters a fractional crystallization device, precipitating calcium sulfate, filtering and collecting calcium sulfate, adding concentrated ammonia water into filtrate to adjust the pH to 5-9, adding a crystallization agent, precipitating ammonium sulfate crystals at the temperature of 25-55 ℃ and the stirring intensity of 550-800 r/min, filtering and collecting ammonium sulfate, adding a crystallization inhibitor into the filtrate, filtering, and concentrating the filtrate to obtain sodium chloride crystals;
the anode plate is a self-cleaning luminous photoelectric synergistic catalytic electrode, the cathode plate is an electrode with one surface covered with a hole transmission layer and the other surface covered with a piezoelectric layer, the hole transmission layer is made of manganese oxide, the piezoelectric layer is made of piezoelectric particles and piezoelectric polymers, the piezoelectric particles are made of more than 2 of zinc oxide, aluminum oxide and silicon dioxide, the piezoelectric polymers are PVDF, the substrate is platinum, titanium, zirconium or ruthenium, the power supply is alternating current or pulse electricity, and the current density is 15-30 mA/cm 2 ；
The crystallization agent is dimethyl sulfoxide, absolute methanol or absolute ethanol, the addition amount is 300-500 mL of each 1L of filtrate, the crystallization inhibitor is polycarboxylate or polyether nonionic surfactant, and the addition amount is 40-150 g of each 1L of filtrate.
2. The method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and hierarchical crystallization recycling according to claim 1, which is characterized in that: the aeration medium is air.
3. The method for purifying organic salt-containing wastewater by photoelectrocatalytic oxidation and hierarchical crystallization recycling according to claim 1, which is characterized in that: the ultrasonic descaling anti-blocking device is a pipeline with a plurality of ultrasonic transducers, the amplitude of the ultrasonic transducers is 10-60 mu m, and the ultrasonic frequency is 40-80 kHz.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107381712A (en) * 2017-08-01 2017-11-24 上海纳米技术及应用国家工程研究中心有限公司 Difficult degradation, high-salt wastewater strengthen the photoelectricity catalytic ozonation method administered
CN109437243A (en) * 2018-10-25 2019-03-08 中国中轻国际工程有限公司 A kind of COD wastewater recycling process with high salt
CN114715984A (en) * 2022-03-28 2022-07-08 昆明理工大学 Self-cleaning luminous photoelectric cooperative catalysis electrode and application thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107381712A (en) * 2017-08-01 2017-11-24 上海纳米技术及应用国家工程研究中心有限公司 Difficult degradation, high-salt wastewater strengthen the photoelectricity catalytic ozonation method administered
CN109437243A (en) * 2018-10-25 2019-03-08 中国中轻国际工程有限公司 A kind of COD wastewater recycling process with high salt
CN114715984A (en) * 2022-03-28 2022-07-08 昆明理工大学 Self-cleaning luminous photoelectric cooperative catalysis electrode and application thereof

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