Method for separating and recycling thiocyanate ions in industrial wastewater

Abstract

The invention discloses a method for separating and recycling thiocyanate ions in industrial wastewater, and belongs to the technical field of industrial wastewater treatment and recycling. The method comprises the following steps: firstly, pretreating industrial wastewater containing thiocyanate ions to remove particulate matters; then introducing into an electrodialysis system, and separating thiocyanate ions from organic matters and carnallite ions; carrying out concentration treatment to obtain a high-power concentrated thiocyanate ion concentrated solution, and carrying out ultrafiltration / UV disinfection on the concentrated solution to be reused in a production section; or cooling and crystallizing to obtain a thiocyanogen product. The method provided by the invention solves the difficult problem of separation and recovery of the thiocyanate ions in the thiocyanate ion-containing industrial wastewater, the separation and recovery rate of the thiocyanate ions reaches 90% or above, the concentration efficiency is 10-40%, and an industrial-grade purity product can be obtained. According to the method, full resource utilization of the solid thiocyanate compound is achieved, no pollution is discharged in the whole technological process, and zero-approaching discharge of the thiocyanate ion-containing industrial wastewater is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of treatment and resource utilization of industrial wastewater containing thiocyanate ions, and in particular to a method for separating and resource utilization of thiocyanate ions in industrial wastewater. Background Art

[0002] In recent years, with the increasing global climate change and environmental problems, the green transformation of industry and the new development mode of green low-carbon cycle have become important paths to achieve sustainable economic and social development and break through resource and environmental constraints. Industrial wastewater containing thiocyanate ions usually has the characteristics of high salt content, high organic matter concentration, high suspended solids content, high chroma, strong odor, high ammonia nitrogen concentration and high salt content. At present, the mainstream treatment methods for industrial wastewater containing thiocyanate ions, such as physical methods, biological methods and chemical methods, mostly directly eliminate or remove the substances in the wastewater, ignoring the presence of high-value substances in the wastewater, such as thiocyanate. Thiocyanate can be used to prepare thiocyanates, esters, various thiocyanides and cyanides, and is widely used in chemical, pharmaceutical and other industries, with great industrial value.

[0003] For the treatment of thiocyanate, industrial efforts are mainly focused on promoting recovery and reuse methods, or applying degradation technology to decompose thiocyanate in wastewater into harmless substances. Various methods and technologies are applied to the separation and recovery of thiocyanate, such as adsorption, photodegradation, membrane extraction, coagulation precipitation, and advanced oxidation. However, there are problems such as high implementation cost and the generation of other pollutants, which leads to low purity of thiocyanate after separation and recovery, which greatly causes waste. Therefore, it is necessary to develop an efficient and low-cost treatment process to achieve separation and recovery of thiocyanate ions and realize resource utilization. Summary of the invention

[0004] The object of the present invention is to provide a method for separating and recycling thiocyanate ions from industrial wastewater, which uses electrodialysis technology to separate and recover thiocyanate ions, effectively remove particulate matter, organic matter and miscellaneous salt ions in industrial wastewater, and realize the separation and recovery of thiocyanate ions.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A method for separating and recycling thiocyanate ions from industrial wastewater includes pre-treating the industrial wastewater containing thiocyanate ions with an ultrafiltration membrane, passing the pre-treated wastewater into an electrodialysis system for electrodialysis, and separating and recycling to obtain a product containing thiocyanate ions; the ultrafiltration membrane is a polysulfone ultrafiltration membrane, which is formed by reacting bis(4-chlorophenyl)sulfone with bisphenol A and then with polyvinylpyrrolidone, and the pore size of the polysulfone ultrafiltration membrane is 0.2-100 μm. The invention first pre-treats the industrial wastewater containing thiocyanate ions, preliminarily removes particulate matter and miscellaneous salt ions in the wastewater, and then passes the wastewater into an electrodialysis system to separate thiocyanate ions from organic matter and miscellaneous salt ions; finally, the thiocyanate product is obtained after RO reverse osmosis and cooling crystallization, and the resource utilization of thiocyanate ions is realized.

[0006] Preferably, the mass ratio of bis(4-chlorophenyl)sulfone to bisphenol A is 1:1-2.

[0007] Preferably, the mass ratio of polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone is 1:3-10.

[0008] Preferably, the ultrafiltration membrane is a modified polysulfone ultrafiltration membrane, and the pore size of the modified polysulfone ultrafiltration membrane is 0.2-100 μm.

[0009] More preferably, in the preparation of the modified polysulfone ultrafiltration membrane, bis(4-chlorophenyl)sulfone is first subjected to a high temperature reaction with a dihydroxy derivative, and then reacted with polyvinylpyrrolidone to form a membrane, wherein the dihydroxy derivative includes at least 4,4'-cyclohexylidene bisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane. The present invention introduces 4,4'-cyclohexylidene bisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane containing a hydrophilic group into the molecular skeleton of the polysulfone ultrafiltration membrane to obtain a polar modified polysulfone ultrafiltration membrane; the modified polysulfone ultrafiltration membrane is first used to pre-treat industrial wastewater, remove particulate matter and initially intercept thiosulfate ions, and then the pre-treated wastewater is passed into an electrodialysis system for treatment, so as to achieve separation of thiocyanate ions from organic matter and miscellaneous salt ions in industrial wastewater, effectively improve the removal efficiency of thiosulfate ions in thiocyanate wastewater, and thus improve the separation recovery rate of thiocyanate ions.

[0010] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to 4,4'-cyclohexylidenebisphenol is 1:0.5-1.

[0011] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to 2,2-bis(4-hydroxy-3-aminophenyl)propane is 1:0.5-1.

[0012] More preferably, the mass ratio of polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone is 1:3-10.

[0013] More preferably, in the high temperature reaction, the reaction temperature is 140-160°C.

[0014] More preferably, in the high temperature reaction, the reaction time is 6-15h.

[0015] Preferably, the ultrafiltration membrane comprises a polysulfone ultrafiltration membrane or a modified polysulfone ultrafiltration membrane.

[0016] Preferably, the preparation of the ultrafiltration membrane comprises: Mix a dihydroxy compound and bis(4-chlorophenyl)sulfone, add N,N-dimethylacetamide and stir to dissolve, then add potassium carbonate and toluene, react at 140-160°C for 6-15h, cool to room temperature, add polyvinylpyrrolidone, stir at 70-90°C until completely dissolved, and vacuum degass to obtain a casting liquid; pour the casting liquid onto a glass plate at room temperature, use a scraper with a gap of 0.2-1μm to scrape it into a flat membrane, then put the glass plate into pure water for 20-40s, peel off the flat membrane from the glass plate, wash the flat membrane with pure water for 2-5 times, and obtain an ultrafiltration membrane.

[0017] More preferably, the dihydroxy compound includes at least one of bisphenol A, 4,4'-cyclohexylenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane and 2-quinolinediol. The present invention further introduces 2-quinolinediol into the molecular skeleton of the polysulfone ultrafiltration membrane to obtain a modified polysulfone ultrafiltration membrane; the modified polysulfone ultrafiltration membrane is used to separate and recover thiocyanate ions from industrial wastewater containing thiocyanate ions, which helps to further improve the removal efficiency of thiosulfate in thiocyanate wastewater and improve the separation and recovery rate of thiocyanate ions.

[0018] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to bisphenol A is 1:1-2.

[0019] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to 4,4'-cyclohexylidenebisphenol is 1:0.5-1.

[0020] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to 2,2-bis(4-hydroxy-3-aminophenyl)propane is 1:0.5-1.

[0021] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to 2-quinolinediol is 1:0.5-1.

[0022] More preferably, the usage ratio of bis(4-chlorophenyl)sulfone to N,N-dimethylacetamide is 1 g:5-10 mL.

[0023] More preferably, the mass ratio of bis(4-chlorophenyl)sulfone to potassium carbonate is 1:0.2-0.7.

[0024] More preferably, the volume ratio of toluene to N,N-dimethylacetamide is 1:2-10.

[0025] More preferably, the mass ratio of polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone is 1:3-10.

[0026] Preferably, the electrodialysis system comprises a power supply, a flow meter, a membrane stack, a circulation pump and a water tank.

[0027] More preferably, the membrane stack includes an anode electrode plate, an anode separator, a cathode separator, a cathode electrode plate and a membrane unit. The separator is a separator commonly used in the field of electrodialysis. The anode electrode plate and the cathode electrode plate are respectively arranged at the two ends of the membrane stack, the anode electrode plate is connected to the positive pole of the power supply, and the cathode electrode plate is connected to the negative pole of the power supply. The membrane unit is located between the anode electrode plate and the cathode electrode plate, and includes an anion exchange membrane and a repeating unit membrane in the direction from the anode electrode plate to the cathode electrode plate; in the repeating unit membrane, the unit membrane formed by the cation exchange membrane and the anion exchange membrane is repeatedly arranged, and the number of the repeating unit membranes is 2-20. The anode electrode plate, the membrane stack and the cathode electrode plate are spaced to form a membrane stack anode chamber, a repeating unit chamber and a membrane stack cathode chamber in turn, and the repeating unit chamber is a repeating unit chamber formed by a dilute chamber and a concentrated chamber, and the number of the repeating unit chamber corresponds to the number of the repeating unit membranes.

[0028] More preferably, the membrane resistance of the membrane unit is 3-6Ω / cm 2 The exchange capacity is greater than 1.3 mol / kg, and the pH value of acid and alkalinity resistance is 2-10.

[0029] More preferably, the membrane stack voltage is 5-50V, and the membrane stack flow rate is 1000-10000mL / min.

[0030] More preferably, the water tank includes an electrode chamber water tank, a concentration chamber water tank and a dilute chamber water tank. The electrode chamber water tank stores the electrode liquid, and is connected to the cathode chamber and anode chamber of the membrane stack on the cathode plate and anode plate at both ends of the membrane stack through a conduit; the concentration chamber water tank stores the separated thiocyanate solution, and is connected to the water inlet and outlet of the concentration chamber of the membrane stack through a conduit; the dilute chamber water tank stores a mixed solution containing thiocyanate ions, impurities and organic matter, and is connected to the water inlet and outlet of the dilute chamber of the membrane stack through a conduit, so that the mixed solution flows from the dilute chamber water tank into the membrane stack and then flows back to the dilute chamber water tank.

[0031] More preferably, the polar liquid is a sodium sulfate solution, and the concentration of the sodium sulfate solution is 0.05-0.1 mol / L.

[0032] Preferably, a method for separating and recycling thiocyanate ions from industrial wastewater comprises: S1. Pretreatment of industrial wastewater containing thiocyanate ions: Before pretreatment, use pure water to pre-press the ultrafiltration membrane at 0.1-0.15MPa for 20-40min, then adjust the pressure to 0.05-0.1MPa for 1h, and pass the industrial wastewater containing thiocyanate ions through the polysulfone ultrafiltration membrane at 0.05-0.1MPa to obtain pretreated wastewater. The ultrafiltration membrane is a polysulfone ultrafiltration membrane or a modified polysulfone ultrafiltration membrane.

[0033] S2, thiocyanate ion separation: the pretreated wastewater is passed into the electrodialysis system, and the wastewater is placed in the dilute chamber water tank as the dilute chamber solution, ultrapure water is used as the concentrated chamber solution to enter the concentrated chamber water tank, and the sodium sulfate solution with a concentration of 0.05-0.1mol / L is used as the pole liquid to enter the pole chamber water tank, and the volume of the dilute chamber solution, the concentrated chamber solution and the pole liquid are kept consistent. Turn on the circulation pump, and transport the pole liquid, the concentrated chamber solution and the dilute chamber solution stored in each water tank to the corresponding compartments in the membrane stack respectively; turn on the DC power supply, and the solution entering the membrane stack is subjected to electrodialysis, ion migration, etc. under the conditions of 10-30V constant voltage and 600-800r / min, and then flows out from the corresponding compartments in the membrane stack and flows back to the corresponding water tanks; the pole liquid, the concentrated chamber solution and the dilute chamber solution circulate back and forth between the water tank and the membrane stack to perform the electrodialysis reaction until the conductivity of the electrolyte solution in the concentrated chamber water tank is reduced to remain unchanged, stop the reaction, turn off the power supply, and obtain the electrodialysis primary separation concentrated chamber effluent. Then, the effluent from the primary separation concentration chamber of electrodialysis is introduced into the electrodialysis system, and the effluent from the primary separation concentration chamber of electrodialysis is placed in the dilute chamber water tank as the dilute chamber solution. This step is repeated to obtain thiocyanate wastewater.

[0034] S3. Preliminary concentration of thiocyanate ions: The thiocyanate wastewater obtained in step S2 is introduced into the electrodialysis system, and the thiocyanate wastewater is placed in the dilute chamber water tank as the dilute chamber solution, ultrapure water is introduced into the concentrated chamber water tank as the concentrated chamber solution, and a sodium sulfate solution with a concentration of 0.05-0.1 mol / L is introduced into the polar chamber water tank as the polar liquid, and the volumes of the dilute chamber solution, the concentrated chamber solution and the polar liquid are kept consistent. Start the circulation pump to transport the cathode solution, concentrated chamber solution and dilute chamber solution stored in each water tank to the corresponding compartments in the membrane stack respectively; turn on the DC power supply, and the solution entering the membrane stack undergoes electrodialysis and ion migration at a constant voltage of 10-30V and 600-800r / min, and then flows out from the corresponding compartments in the membrane stack and flows back to the corresponding water tanks; the cathode solution, concentrated chamber solution and dilute chamber solution circulate back and forth between the water tank and the membrane stack to undergo electrodialysis reaction until the conductivity of the electrolyte solution in the concentrated chamber water tank is reduced to a constant value, the reaction is stopped, the power is turned off, and a preliminary concentrated solution of thiocyanate ions is obtained.

[0035] S4. High concentration of thiocyanate ions and recovery of thiocyanate product: The preliminary concentrated solution of thiocyanate ions is subjected to RO reverse osmosis treatment, with a spiral membrane element as the RO membrane element, a separation and screening particle size of 0.1-0.9nm, a membrane flux of 10-20LMH, and highly concentrated concentrated water is obtained after RO reverse osmosis treatment; the concentrated water is then subjected to cooling crystallization treatment, the crystallization temperature is 0-10°C, the stirring rate is 500-2000rpm, the concentrated water residence time is 1-2h, and the thiocyanate product is obtained after treatment.

[0036] The invention adopts a modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylidenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 2-quinolinediol and bis(4-chlorophenyl)sulfone to pre-treat industrial wastewater, and then obtains a thiocyanate product through electrodialysis system treatment, RO reverse osmosis treatment and cooling crystallization. Therefore, the invention has the following beneficial effects: the modified polysulfone ultrafiltration membrane prepared by the invention first pre-treats industrial wastewater, removes particulate matter and preliminarily intercepts thiosulfate ions, and then passes the pre-treated wastewater into the electrodialysis system for treatment, effectively improving the removal efficiency of thiosulfate ions in thiocyanate wastewater, thereby improving the separation recovery rate of thiocyanate ions; then the thiocyanate product is obtained through electrodialysis preliminary concentration, RO reverse osmosis treatment and cooling crystallization. The method of the invention solves the problem of separation and recovery of thiocyanate ions in industrial wastewater containing thiocyanate ions, realizes full resource utilization of solid thiocyanate compounds, has no pollution discharge in the whole process, and promotes zero discharge of industrial wastewater containing thiocyanate ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is the process flow chart for separation and resource utilization of thiocyanate ions in industrial wastewater.

[0038] Figure 2 This is the device structure diagram of the electrodialysis system.

[0039] Figure 3 Schematic diagram of the principle of separating and recovering thiocyanate ions.

[0040] Figure 4 is the concentration of thiocyanate ions in thiocyanate wastewater. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0042] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0043] Embodiment 1: Preparation of polysulfone ultrafiltration membrane, comprising: Bisphenol A and bis(4-chlorophenyl)sulfone were mixed, N,N-dimethylacetamide was added and stirred to dissolve, potassium carbonate and toluene were added, reacted at 150℃ for 12h, cooled to room temperature, polyvinyl pyrrolidone was added, stirred at 80℃ until completely dissolved, vacuum degassing was performed to obtain a casting solution; the casting solution was poured onto a glass plate at room temperature, and a scraper with a gap of 0.3μm was used to scrape a flat film, and then the glass plate was immersed in pure water for 30s, the flat film was peeled off from the glass plate, and the flat film was washed 3 times with pure water to obtain a polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl)sulfone to bisphenol A was 1:1; the dosage ratio of bis(4-chlorophenyl)sulfone to N,N-dimethylacetamide was 1g:7mL; the mass ratio of bis(4-chlorophenyl)sulfone to potassium carbonate was 1:0.5; the volume ratio of toluene to N,N-dimethylacetamide was 1:5; the mass ratio of polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone was 1:6.

[0044] The electrodialysis system includes a power supply, a flow meter, a membrane stack, a circulation pump and a water tank. The membrane stack includes an anode electrode plate, a separator, a cathode electrode plate and a membrane unit. The separator is a separator commonly used in the field of electrodialysis. The anode electrode plate and the cathode electrode plate are respectively arranged at the two ends of the membrane stack, the anode electrode plate is connected to the positive electrode of the power supply, and the cathode electrode plate is connected to the negative electrode of the power supply. The membrane unit is located between the anode electrode plate and the cathode electrode plate, and includes an anion exchange membrane and a repeating unit membrane in the direction from the anode electrode plate to the cathode electrode plate; in the repeating unit membrane, the unit membrane formed by the cation exchange membrane and the anion exchange membrane is repeatedly arranged, and the number of the repeating unit membranes is 2. The anode electrode plate, the membrane stack and the cathode electrode plate are separated to form a membrane stack anode chamber, a repeating unit chamber and a membrane stack cathode chamber in turn, and the repeating unit chamber is a repeating unit chamber formed by a dilute chamber and a concentrated chamber, and the number of the repeating unit chambers corresponds to the number of the repeating unit membranes. The membrane resistance of the membrane unit is 5Ω / cm2, the exchange capacity is 1.3mol / kg, and the pH value of the acid and alkalinity resistance is 2. The voltage of the membrane stack is 20V, and the flow rate of the membrane stack is 2000mL / min. The water tank includes a cathode chamber water tank, a concentration chamber water tank and a dilute chamber water tank. The cathode liquid is stored in the cathode chamber water tank, which is connected to the cathode chamber and anode chamber of the membrane stack on the cathode plate and anode plate at both ends of the membrane stack through a conduit; the separated thiocyanate solution is stored in the concentration chamber water tank, which is connected to the water inlet and outlet of the concentration chamber of the membrane stack through a conduit; the mixed solution containing thiocyanate ions, impurities and organic matter is stored in the dilute chamber water tank, which is connected to the water inlet and outlet of the dilute chamber of the membrane stack through a conduit.

[0045] A method for separating and recycling thiocyanate ions from industrial wastewater, comprising: S1. Pretreatment of industrial wastewater containing thiocyanate ions: Before pretreatment, use pure water to pre-press the polysulfone ultrafiltration membrane at 0.15MPa for 30 minutes, then adjust the pressure to 0.1MPa for 1 hour, and pass the industrial wastewater containing thiocyanate ions through the polysulfone ultrafiltration membrane under 0.1MPa conditions to obtain pretreated industrial wastewater containing thiocyanate ions.

[0046] S2, thiocyanate ion separation: the pretreated wastewater is passed into the electrodialysis system, and the wastewater is placed in the dilute chamber water tank as the dilute chamber solution, ultrapure water is used as the concentrated chamber solution to enter the concentrated chamber water tank, and a sodium sulfate solution with a concentration of 0.1 mol / L is used as the pole liquid to enter the pole chamber water tank, and the volume of the dilute chamber solution, the concentrated chamber solution and the pole liquid is kept consistent. Turn on the circulation pump, and transport the pole liquid, the concentrated chamber solution and the dilute chamber solution stored in each water tank to the corresponding compartments in the membrane stack respectively; turn on the DC power supply, and the solution entering the membrane stack is subjected to electrodialysis, ion migration, etc. under the conditions of 20V constant voltage and 700r / min, and then flows out from the corresponding compartments in the membrane stack and flows back to the corresponding water tanks; the pole liquid, the concentrated chamber solution and the dilute chamber solution circulate back and forth between the water tank and the membrane stack to perform the electrodialysis reaction until the conductivity of the electrolyte solution in the concentrated chamber water tank is reduced to remain unchanged, stop the reaction, turn off the power supply, and obtain the electrodialysis primary separation concentrated chamber effluent. Then, the effluent from the primary separation concentration chamber of electrodialysis is introduced into the electrodialysis system, and the effluent from the primary separation concentration chamber of electrodialysis is placed in the dilute chamber water tank as the dilute chamber solution. This step is repeated to obtain thiocyanate wastewater.

[0047] S3, preliminary concentration of thiocyanate ions: the thiocyanate wastewater obtained in step S2 is passed into the electrodialysis system, the thiocyanate wastewater is placed in the dilute chamber water tank as the dilute chamber solution, ultrapure water is used as the concentrated chamber solution to enter the concentrated chamber water tank, and a sodium sulfate solution with a concentration of 0.1 mol / L is used as the pole liquid to enter the pole chamber water tank, and the volume of the dilute chamber solution, the concentrated chamber solution and the pole liquid are kept consistent. The circulating pump is turned on to transport the pole liquid, the concentrated chamber solution and the dilute chamber solution stored in each water tank to the corresponding compartments in the membrane stack respectively; the DC power supply is turned on, and the solution entering the membrane stack is subjected to electrodialysis, ion migration, etc. under the conditions of 230V constant voltage and 700r / min, and then flows out from the corresponding compartments in the membrane stack and flows back to the corresponding water tanks; the pole liquid, the concentrated chamber solution and the dilute chamber solution circulate back and forth between the water tank and the membrane stack to perform an electrodialysis reaction until the conductivity of the electrolyte solution in the concentrated chamber water tank is reduced to remain unchanged, the reaction is stopped, the power supply is turned off, and the preliminary concentrated solution of thiocyanate ions is obtained.

[0048] S4. High concentration of thiocyanate ions and recovery of thiocyanate product: The preliminary concentrated solution of thiocyanate ions is subjected to RO reverse osmosis treatment, with a spiral membrane element as the RO membrane element, a separation and screening particle size of 0.45 nm, and a membrane flux of 15 LMH. After RO reverse osmosis treatment, highly concentrated concentrated water is obtained; the concentrated water is then subjected to cooling crystallization treatment, with a crystallization temperature of 5°C, a stirring rate of 1000 rpm, and a concentrated water residence treatment time of 1 hour. After treatment, a thiocyanate ion-containing product is obtained.

[0049] Embodiment 2: Preparation of modified polysulfone ultrafiltration membrane, comprising: Mix 4,4'-cyclohexylenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone, add N,N-dimethylacetamide and stir to dissolve, then add potassium carbonate and toluene, react at 150°C for 12h, cool to room temperature, add polyvinylpyrrolidone, stir until completely dissolved at 80°C, and vacuum degas to obtain a casting solution; pour the casting solution onto a glass plate at room temperature, use a scraper with a gap of 0.3μm to scrape it into a flat membrane, then put the glass plate into pure water for 30s, peel off the flat membrane from the glass plate, wash the flat membrane with pure water 3 times, and obtain a modified polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl) sulfone and 4,4'-cyclohexylenebisphenol is 1:1; the mass ratio of bis(4-chlorophenyl) sulfone and 2,2-bis(4-hydroxy-3-aminophenyl) propane is 1:1; the dosage ratio of bis(4-chlorophenyl) sulfone and N,N-dimethylacetamide is 1g:7mL; the mass ratio of bis(4-chlorophenyl) sulfone and potassium carbonate is 1:0.5; the volume ratio of toluene and N,N-dimethylacetamide is 1:5; the mass ratio of polyvinylpyrrolidone and bis(4-chlorophenyl) sulfone is 1:6.

[0050] The electrodialysis system is the same as that in Example 1.

[0051] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0052] Embodiment 3: The preparation of the modified polysulfone ultrafiltration membrane was compared with Example 2, except that the mass ratio of bis(4-chlorophenyl)sulfone to 4,4'-cyclohexylidenebisphenol was changed to 1:0.5, and other conditions were the same as Example 2.

[0053] The electrodialysis system is the same as that in Example 1.

[0054] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0055] Embodiment 4: The preparation of the modified polysulfone ultrafiltration membrane is compared with Example 2, except that the mass ratio of bis(4-chlorophenyl)sulfone to 2,2-bis(4-hydroxy-3-aminophenyl)propane is replaced with 1:0.5, and other conditions are the same as Example 2.

[0056] The electrodialysis system is the same as that in Example 1.

[0057] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0058] Embodiment 5: Preparation of modified polysulfone ultrafiltration membrane, comprising: 4,4'-cyclohexylenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 2-quinolinediol and bis(4-chlorophenyl)sulfone were mixed, N,N-dimethylacetamide was added and stirred to dissolve, potassium carbonate and toluene were added, the mixture was reacted at 150°C for 12 hours, the mixture was cooled to room temperature, polyvinylpyrrolidone was added, the mixture was stirred at 80°C until the mixture was completely dissolved, and vacuum degassing was performed to obtain a casting solution; the casting solution was poured onto a glass plate at room temperature, a scraper with a gap of 0.3 μm was used to scrape the film into a flat film, the glass plate was immersed in pure water for 30 seconds, the flat film was peeled off from the glass plate, and the flat film was washed with pure water for 3 times to obtain a modified polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl) sulfone and 4,4'-cyclohexylenebisphenol is 1:1; the mass ratio of bis(4-chlorophenyl) sulfone and 2,2-bis(4-hydroxy-3-aminophenyl) propane is 1:1; the mass ratio of bis(4-chlorophenyl) sulfone and 2-quinolinediol is 1:1; the dosage ratio of bis(4-chlorophenyl) sulfone and N,N-dimethylacetamide is 1g:7mL; the mass ratio of bis(4-chlorophenyl) sulfone and potassium carbonate is 1:0.5; the volume ratio of toluene and N,N-dimethylacetamide is 1:5; the mass ratio of polyvinylpyrrolidone and bis(4-chlorophenyl) sulfone is 1:6.

[0059] The electrodialysis system is the same as that in Example 1.

[0060] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0061] Embodiment 6: The preparation of the modified polysulfone ultrafiltration membrane was compared with Example 5, except that the mass ratio of bis(4-chlorophenyl)sulfone to 2-quinolinediol was changed to 1::0.5, and other conditions were the same as Example 5.

[0062] The electrodialysis system is the same as that in Example 1.

[0063] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0064] Comparative Example 1: Preparation of modified polysulfone ultrafiltration membrane, comprising: Mix 4,4'-cyclohexylenebisphenol and bis(4-chlorophenyl)sulfone, add N,N-dimethylacetamide and stir to dissolve, then add potassium carbonate and toluene, react at 150°C for 12 hours, cool to room temperature, add polyvinylpyrrolidone, stir until completely dissolved at 80°C, and vacuum degass to obtain a casting liquid; pour the casting liquid onto a glass plate at room temperature, use a scraper with a gap of 0.3 μm to scrape it into a flat membrane, then put the glass plate into pure water for 30 seconds, peel off the flat membrane from the glass plate, wash the flat membrane with pure water 3 times, and obtain a modified polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl) sulfone and 4,4'-cyclohexylenebisphenol is 1:1; the dosage ratio of bis(4-chlorophenyl) sulfone and N,N-dimethylacetamide is 1g:7mL; the mass ratio of bis(4-chlorophenyl) sulfone and potassium carbonate is 1:0.5; the volume ratio of toluene and N,N-dimethylacetamide is 1:5; the mass ratio of polyvinylpyrrolidone and bis(4-chlorophenyl) sulfone is 1:6.

[0065] The electrodialysis system is the same as that in Example 1.

[0066] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0067] Comparative Example 2: Preparation of modified polysulfone ultrafiltration membrane, comprising: Mix 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone, add N,N-dimethylacetamide and stir to dissolve, then add potassium carbonate and toluene, react at 150°C for 12 hours, cool to room temperature, add polyvinylpyrrolidone, stir at 80°C until completely dissolved, and vacuum degassing to obtain a casting liquid; pour the casting liquid onto a glass plate at room temperature, use a scraper with a gap of 0.3 μm to scrape it into a flat membrane, then put the glass plate into pure water for 30 seconds, peel off the flat membrane from the glass plate, wash the flat membrane with pure water 3 times, and obtain a modified polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl) sulfone and 2,2-bis(4-hydroxy-3-aminophenyl) propane is 1:1; the dosage ratio of bis(4-chlorophenyl) sulfone and N,N-dimethylacetamide is 1g:7mL; the mass ratio of bis(4-chlorophenyl) sulfone and potassium carbonate is 1:0.5; the volume ratio of toluene and N,N-dimethylacetamide is 1:5; the mass ratio of polyvinylpyrrolidone and bis(4-chlorophenyl) sulfone is 1:6.

[0068] The electrodialysis system is the same as that in Example 1.

[0069] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0070] Comparative Example 3: Preparation of modified polysulfone ultrafiltration membrane, comprising: 2-quinolinediol and bis(4-chlorophenyl)sulfone were mixed, N,N-dimethylacetamide was added and stirred to dissolve, potassium carbonate and toluene were added, the reaction was carried out at 150°C for 12 hours, the temperature was lowered to room temperature, polyvinylpyrrolidone was added, the mixture was stirred at 80°C until it was completely dissolved, and vacuum degassing was performed to obtain a casting liquid; the casting liquid was poured onto a glass plate at room temperature, a scraper with a gap of 0.3 μm was used to scrape the film into a flat film, the glass plate was immersed in pure water for 30 seconds, the flat film was peeled off from the glass plate, and the flat film was washed 3 times with pure water to obtain a modified polysulfone ultrafiltration membrane. The mass ratio of bis(4-chlorophenyl) sulfone and 2-quinolinediol is 1:1; the dosage ratio of bis(4-chlorophenyl) sulfone and N,N-dimethylacetamide is 1g:7mL; the mass ratio of bis(4-chlorophenyl) sulfone and potassium carbonate is 1:0.5; the volume ratio of toluene and N,N-dimethylacetamide is 1:5; the mass ratio of polyvinylpyrrolidone and bis(4-chlorophenyl) sulfone is 1:6.

[0071] The electrodialysis system is the same as that in Example 1.

[0072] A method for separating and recycling thiocyanate ions from industrial wastewater is disclosed. Compared with Example 1, except that the polysulfone ultrafiltration membrane is replaced by the modified polysulfone ultrafiltration membrane prepared in this example, other conditions are the same as those in Example 1.

[0073] Experimental example: 1. Thiocyanate ion concentration detection The coke oven gas desulfurization industrial wastewater was treated according to the method of Example 1. The thiocyanate ion concentration in the coke oven gas desulfurization industrial wastewater was 2300 mg / L. Figure 1 This is a process flow chart for separation and resource utilization of thiocyanate ions in industrial wastewater. First, the industrial wastewater is pretreated to remove particulate matter and thiosulfate ions in the wastewater, achieve preliminary separation of thiocyanate ions, and obtain pretreated wastewater; then the pretreated wastewater is passed into an electrodialysis system to separate thiocyanate ions from organic matter and miscellaneous salt ions in the wastewater to obtain thiocyanate wastewater; the thiocyanate wastewater is subjected to RO reverse osmosis and cooling crystallization to separate and recover thiocyanate ions to obtain a thiocyanate product.

[0074] Figure 2 It is a device structure diagram of the electrodialysis system, wherein 1 is the electrodialysis power supply, 2 is the electrodialysis membrane stack, 3 is the membrane stack water inlet, 4 is the membrane stack water outlet, 5 is the electrode plate, 6 is the ion exchange membrane, 7 is the power cord, 8 is the conduit, 9 is the discharge tank, 10 is the feed tank, 11 is the polar liquid tank, 12 is the positive electrode of the electrode plate, and 13 is the negative electrode of the electrode plate. Figure 3 This is a schematic diagram of the principle of electrodialysis system for separation and recovery of thiocyanate ions. AEM is an anion exchange membrane and CEM is a cation exchange membrane. Under the action of the electric field force, the solutions in the cathode chamber, dilute chamber and concentrated chamber circulate back and forth to perform electrodialysis, ion migration, etc., thereby separating thiocyanate ions.

[0075] The pretreated wastewater is passed through an electrodialysis system for treatment to obtain effluent from the electrodialysis primary separation concentration chamber; the effluent from the electrodialysis primary separation concentration chamber is then passed through an electrodialysis system for treatment. At 0, 5, 15, 30, 60, and 90 minutes of treatment, thiocyanate wastewater is collected, and ferric chloride is added for complexation. After the reaction is completed, the thiocyanate ion concentration is determined by ultraviolet spectrometry. Figure 4 is the concentration of thiocyanate ions in thiocyanate wastewater, Figure 4 It can be seen that the thiocyanate concentration increases with the increase of the electrodialysis system treatment time. At the 90th minute of treatment, the thiocyanate ion concentration in the obtained thiocyanate wastewater is 1800 mg / L. This shows that the present invention can effectively separate and recover thiocyanate ions by passing the pretreated wastewater into the electrodialysis system.

[0076] 2. Separation and recovery rate of thiocyanate ion First, the polysulfone ultrafiltration membrane prepared in Example 1 and the modified polysulfone ultrafiltration membrane prepared in Examples 2-6 and Comparative Examples 1-3 are used to pretreat the coke oven gas desulfurization industrial wastewater to obtain the pretreated wastewater of the corresponding treatment group; then the pretreated wastewater of each group is passed into the electrodialysis system for treatment to obtain the effluent of the electrodialysis primary separation concentration chamber; then the effluent of the electrodialysis primary separation concentration chamber is passed into the electrodialysis system for treatment for 90 minutes to obtain the corresponding thiocyanate wastewater. The concentration of thiocyanate ions in the coke oven gas desulfurization industrial wastewater is 2300 mg / L. The separation recovery rate is determined as follows: ferric chloride is added to the thiocyanate wastewater for complexation, and the thiocyanate ion concentration is determined by ultraviolet spectrophotometry after the reaction is completed, and the thiocyanate ion separation recovery rate is calculated. Thiocyanate ion separation recovery rate (%) = thiocyanate ion concentration in thiocyanate wastewater / thiocyanate ion concentration in coke oven gas desulfurization industrial wastewater × 100%. The measurement results are shown in Table 1.

[0077] Table 1 Thiocyanate ion separation recovery rate (%)

[0078] As can be seen from Table 1, the thiocyanate ion separation recovery rate of Examples 2-4 of the present invention is higher than that of Example 1, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Example 2 first uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylidene bisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone to treat industrial wastewater, and then performs electrodialysis system treatment; while Example 1 first uses a polysulfone ultrafiltration membrane prepared by the reaction of bisphenol A and bis(4-chlorophenyl)sulfone to pre-treat industrial wastewater. The thiocyanate ion separation recovery rate of Example 2 is higher than that of Examples 3-4, because in the preparation of the modified polysulfone ultrafiltration membrane, the amounts of 4,4'-cyclohexylidene bisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane used are different. The separation recovery rate of thiocyanate ions in Example 2 is higher than that in Comparative Examples 1-2 because, in the separation and recycling of thiocyanate ions in industrial wastewater, Comparative Example 1 only uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylene bisphenol and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater, and Comparative Example 2 only uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater. This shows that the present invention uses a modified polysulfone ultrafiltration membrane prepared by 4,4'-cyclohexylene bisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane to pretreat industrial wastewater, and then performs electrodialysis system treatment, which can improve the separation recovery rate of thiocyanate ions in thiocyanate wastewater.

[0079] The thiocyanate ion separation recovery rate of Examples 5-6 of the present invention is higher than that of Example 2, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Examples 5-6 use 4,4'-cyclohexylene bisphenol, 2,2-bis(4-hydroxy-3-aminophenyl) propane, 2-quinoline diol and bis(4-chlorophenyl) sulfone to prepare the modified polysulfone ultrafiltration membrane for pretreatment of industrial wastewater, and then perform electrodialysis system treatment. The thiocyanate ion separation recovery rate of Example 5 is higher than that of Example 6, because in the preparation of the modified polysulfone ultrafiltration membrane, the amount of 2-quinoline diol used is different. The thiocyanate ion separation recovery rate of Examples 5-6 is higher than that of Comparative Example 3, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Comparative Example 3 only uses 2-quinoline diol and bis(4-chlorophenyl) sulfone to prepare the modified polysulfone ultrafiltration membrane for pretreatment of industrial wastewater. This shows that the use of modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylidenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 2-quinolinediol and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater and then treat it with an electrodialysis system can further improve the separation and recovery rate of thiocyanate ions in thiocyanate wastewater.

[0080] 3. Removal efficiency of thiosulfate ions Industrial wastewater containing thiocyanate ions contains a large amount of sulfur-containing impurities, such as thiosulfate ions. Sulfur-containing impurities are generated as by-products during industrial wastewater treatment, thereby affecting the separation and recovery of thiocyanate ions. Therefore, it is necessary to remove sulfur-containing impurities in industrial wastewater containing thiocyanate ions.

[0081] First, the polysulfone ultrafiltration membrane prepared in Example 1, and the modified polysulfone ultrafiltration membranes prepared in Examples 2-6 and Comparative Examples 1-3 are used to pretreat the coke oven gas desulfurization industrial wastewater to obtain the pretreated wastewater of the corresponding treatment group; then the pretreated wastewater of each group is passed into the electrodialysis system for treatment to obtain the effluent of the electrodialysis primary separation concentration chamber; then the effluent of the electrodialysis primary separation concentration chamber is passed into the electrodialysis system for treatment for 90 minutes to obtain the corresponding thiocyanate wastewater. The concentration of thiosulfate ions in the coke oven gas desulfurization industrial wastewater is 1128 mg / L. The determination steps of the thiosulfate ion concentration are as follows: add dilute hydrochloric acid to the thiocyanate wastewater to adjust the pH to acidic, then add sodium tetrachloromercurate, formaldehyde and pararosaniline hydrochloride to react to form a purple-red complex, and determine the thiosulfate ion concentration (g / L) by colorimetry. Thiosulfate ion removal efficiency (%) = (thiosulfate ion concentration in coke oven gas desulfurization industrial wastewater - thiosulfate ion concentration in thiocyanate wastewater) × 100%. The measurement results are shown in Table 2.

[0082] Table 2 Thiosulfate ion removal efficiency (%)

[0083] As can be seen from Table 2, the thiosulfate ion removal efficiency of Examples 2-4 of the present invention is higher than that of Example 1, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Example 2 first uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylidene bisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone to treat industrial wastewater, and then performs electrodialysis system treatment; while Example 1 first uses a polysulfone ultrafiltration membrane prepared by the reaction of bisphenol A and bis(4-chlorophenyl)sulfone to pre-treat industrial wastewater. The thiosulfate ion removal efficiency of Example 2 is higher than that of Examples 3-4, because in the preparation of the modified polysulfone ultrafiltration membrane, the amounts of 4,4'-cyclohexylidene bisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane used are different. The thiosulfate ion removal efficiency of Example 2 is higher than that of Comparative Examples 1-2 because, in the separation and resource utilization of thiocyanate ions in industrial wastewater, Comparative Example 1 only uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylenebisphenol and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater, and Comparative Example 2 only uses a modified polysulfone ultrafiltration membrane prepared by the reaction of 2,2-bis(4-hydroxy-3-aminophenyl)propane and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater. This shows that the present invention uses a modified polysulfone ultrafiltration membrane prepared by 4,4'-cyclohexylenebisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane to pretreat industrial wastewater, and then performs electrodialysis system treatment, which can improve the thiosulfate ion removal efficiency in thiocyanate wastewater.

[0084] The thiosulfate ion removal efficiency of Examples 5-6 of the present invention is higher than that of Example 2, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Examples 5-6 use 4,4'-cyclohexylene bisphenol, 2,2-bis(4-hydroxy-3-aminophenyl) propane, 2-quinoline diol and bis(4-chlorophenyl) sulfone to prepare the modified polysulfone ultrafiltration membrane for pretreatment of industrial wastewater, and then perform electrodialysis system treatment. The thiosulfate ion removal efficiency of Example 5 is higher than that of Example 6, because in the preparation of the modified polysulfone ultrafiltration membrane, the amount of 2-quinoline diol used is different. The thiosulfate ion removal efficiency of Examples 5-6 is higher than that of Comparative Example 3, because in the separation and resource utilization of thiocyanate ions in industrial wastewater, Comparative Example 3 only uses 2-quinoline diol and bis(4-chlorophenyl) sulfone to prepare the modified polysulfone ultrafiltration membrane for pretreatment of industrial wastewater. This shows that the use of modified polysulfone ultrafiltration membrane prepared by the reaction of 4,4'-cyclohexylidenebisphenol, 2,2-bis(4-hydroxy-3-aminophenyl)propane, 2-quinolinediol and bis(4-chlorophenyl)sulfone to pretreat industrial wastewater and then treat it with an electrodialysis system can further improve the removal efficiency of thiosulfate ions in thiocyanate wastewater.

[0085] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0086] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for separating and recycling thiocyanate ions from industrial wastewater, comprising: first using an ultrafiltration membrane to pretreat industrial wastewater containing thiocyanate ions, then passing the pretreated wastewater into an electrodialysis system for electrodialysis, and separating and recovering a thiocyanate ion-containing product; the ultrafiltration membrane is a polysulfone ultrafiltration membrane, the polysulfone ultrafiltration membrane is formed by first reacting bis(4-chlorophenyl) sulfone with bisphenol A and then reacting with polyvinylpyrrolidone, and the pore size of the polysulfone ultrafiltration membrane is 0.2-100 μm.

2. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 1, characterized in that: The mass ratio of the bis(4-chlorophenyl)sulfone to bisphenol A is 1:1-2.

3. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 1, characterized in that: The mass ratio of the polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone is 1:3-10.

4. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 1, characterized in that: The ultrafiltration membrane is a modified polysulfone ultrafiltration membrane, and the pore size of the modified polysulfone ultrafiltration membrane is 0.2-100 μm.

5. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 4, characterized in that: In the preparation of the modified polysulfone ultrafiltration membrane, bis(4-chlorophenyl)sulfone is first reacted with a dihydroxy derivative at high temperature and then reacted with polyvinylpyrrolidone to form a membrane. The dihydroxy derivative includes at least 4,4'-cyclohexylenebisphenol and 2,2-bis(4-hydroxy-3-aminophenyl)propane.

6. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 5, characterized in that: The mass ratio of the bis(4-chlorophenyl)sulfone to 4,4'-cyclohexylenebisphenol is 1:0.5-1.

7. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 5, characterized in that: The mass ratio of the bis(4-chlorophenyl)sulfone to 2,2-bis(4-hydroxy-3-aminophenyl)propane is 1:0.5-1.

8. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 5, characterized in that: The mass ratio of the polyvinyl pyrrolidone to bis(4-chlorophenyl)sulfone is 1:3-10.

9. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 5, characterized in that: In the high temperature reaction, the reaction temperature is 140-160°C.

10. A method for separating and recycling thiocyanate ions from industrial wastewater according to claim 5, characterized in that: In the high temperature reaction, the reaction time is 6-15h.

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