A packed bed electrodialysis device and method for target selective fluorine removal

Abstract

The present invention discloses a packed bed electrodialysis device and method for selective fluorine removal, wherein a packed bed electrodialysis device for selective fluorine removal comprises: a packed bed electrodialysis membrane stack, a pump circuit control system, a water tank, a flow meter, an infusion pump and a pipeline. The packed bed electrodialysis membrane stack comprises: an anion exchange membrane, a cation exchange membrane, a dilute chamber partition, a concentrated chamber partition, an electrode plate and a clamping device, which together constitute the dilute chamber, the concentrated chamber and the electrode chamber of the packed bed electrodialysis membrane stack. The filling material is preferably a material with high adsorption performance for fluoride ions, and the filling material is placed in the dilute chamber of the packed bed electrodialysis device. The pump circuit control system comprises a temperature sensor and a control system. The control system controls operating parameters including voltage, current, concentrated chamber water inlet flow rate and dilute chamber water inlet flow rate. The present invention can be applied to fluorine removal from ionic aqueous solution / brackish water / groundwater, and achieves fluoride ions greater than chloride ions in selectivity, with high efficiency, simple operation and low cost.

Description

Technical Field

[0001] The invention belongs to the field of drinking water treatment, and in particular relates to a packed bed electrodialysis device and method for target selective fluoride removal. Background Art

[0002] Fluoride is an essential element for the human body, but long-term excessive intake of fluoride ions can cause fluorosis, bone tissue disorders, and endocrine gland lesions. In order to ensure healthy drinking water for humans and cope with water shortages, it is necessary to control the fluoride ion content in brackish groundwater during drinking water treatment.

[0003] As a common technology for defluoridation of drinking water, traditional electrodialysis technology can carry out an ion separation process of directional ion migration under a DC electric field, but it faces two problems in the defluoridation process: 1) The concentration of fluoride ions in drinking water is low, lower than anions such as chloride and sulfate; 2) There is a competitive effect between fluoride ions and other anions during defluoridation. In addition to electrodialysis technology, adsorption is also commonly used for defluoridation of drinking water. According to the type of adsorbent, it can be divided into: bone char method, activated alumina, resin adsorption, etc. The advantages of bone char method are that there is no need to adjust the pH value of raw water and the adsorption capacity is large, but the disadvantages are limited raw material sources, complex pretreatment, and high cost; the advantages of activated alumina are simple operation and low cost, but the disadvantages are high requirements for pH and adsorption temperature. Resin adsorption has a stable defluoridation effect, but it is easily contaminated and needs to be considered for regeneration. Coupling multiple processes and giving full play to the advantages of each technology is a potential way to remove fluoride ions. At present, how to efficiently and selectively remove fluoride ions is a focus of new coupling devices for treating brackish groundwater. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a packed bed electrodialysis device and method for selective fluorine removal, which can be applied to the defluorination of brackish groundwater to reduce the health risks caused by fluorine ions, and the treated water can be used as drinking water. The entire process provides an effective selective fluorine removal device and method to achieve a fluorine ion selectivity greater than a chloride ion selectivity.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is:

[0006] A method for selectively removing fluorine from a packed bed electrodialysis device comprises: treating the wastewater to be treated by a packed bed electrodialysis device to obtain fluorine-free treated water; the dilute chamber in the packed bed electrodialysis device is filled with a mixed bed resin, the mixed bed resin comprises a strong base resin and a strong acid resin, the strong base resin is at least one of HP3500, 550A and a styrene resin, and the styrene resin is prepared by reacting a diene compound including at least one of ethylene glycol diallyl ether and N-methyl diallylamine with a styrene monomer. When ethylene glycol diallyl ether and N-methyl diallylamine participate in the preparation of the styrene resin, an ether group and a methyl group are successfully introduced into the structure of the styrene resin, and after further reacting with an aminating agent, a styrene resin-type strong base resin is formed, and after being mixed and filled with the styrene resin and the strong acid resin, the selectivity and removal efficiency of the styrene resin used as a filling material for fluorine ions can be effectively improved under the joint use of the styrene resin having an ether group and a methyl group and the strong acid resin.

[0007] Preferably, the mixing volume ratio of the strong base resin to the strong acid resin in the mixed bed resin is 2:1 to 1:2, and the filling degree of the mixed bed resin is 20 to 100%.

[0008] Preferably, the wastewater to be treated comprises an aqueous solution of chloride ions and an aqueous solution of fluoride ions.

[0009] Preferably, the amount of the strong base resin is 3 to 20 parts by volume.

[0010] Preferably, the method for preparing the styrene resin comprises:

[0011] S1: Mix a styrene-based monomer, a diene compound, an initiator and a pore-forming agent, add a dispersant, and obtain an intermediate resin.

[0012] S2: Add an aminating agent to the intermediate resin and mix them to obtain a styrene resin.

[0013] Preferably, the styrene-based monomer includes chloromethylstyrene, and the amount of chloromethylstyrene used is 80 to 120 parts by weight.

[0014] Preferably, the styrene-based monomer further comprises divinylbenzene, and the amount of divinylbenzene used is 4 to 8 parts by weight.

[0015] Preferably, the amount of the diene compound is 0.5 to 2.5 parts by weight.

[0016] More preferably, the dispersant is a gelatin aqueous solution, and the amount of the dispersant used is 400-600 parts by volume.

[0017] More preferably, the mass fraction of gelatin in the gelatin aqueous solution is 1-3%.

[0018] The present invention provides a packed bed electrodialysis method for target selective fluorine removal, specifically comprising:

[0019] The wastewater to be treated is treated by a packed bed electrodialysis device to obtain defluorinated treated water, wherein the dilute chamber in the packed bed electrodialysis device is filled with a mixed bed resin, and the mixed bed resin includes a strong base resin and a strong acid resin.

[0020] Preferably, in a packed bed electrodialysis method for selective fluorine removal, the mixing volume ratio of the strong base resin to the strong acid resin is 2:1 to 1:2.

[0021] Preferably, in a method for packed bed electrodialysis for targeted selective fluorine removal, the filling degree of the mixed bed resin is 20-100%.

[0022] Preferably, in a packed bed electrodialysis method for targeted selective fluorine removal, the strong base resin is at least one of HP3500, 550A and styrene resin.

[0023] Preferably, in a packed bed electrodialysis method for selective fluorine removal, the amount of the strong base resin used is 3 to 20 parts by volume.

[0024] Preferably, in a packed bed electrodialysis method for selective fluorine removal, the strong acid resin is D001, and the amount of the strong acid resin is 3 to 20 parts by volume.

[0025] More preferably, in a method for selectively removing fluorine from a packed bed, a styrene resin is prepared by reacting a diene compound including at least one of ethylene glycol diallyl ether, N-methyldiallylamine and 1,4-pentadiene-3-ol with a styrene-based monomer. When 1,4-pentadiene-3-ol is involved in the preparation of the styrene resin, 1,4-pentadiene-3-ol is added to the preparation of the styrene resin as a diene compound for reaction, thereby introducing a structure formed by 1,4-pentadiene-3-ol into the styrene resin, and then the styrene resin is used as a strong base resin and a strong acid resin to be filled in an electrodialysis device, which can effectively improve the selectivity and removal efficiency of fluoride ions when the styrene resin is used as a filling material.

[0026] More preferably, in a packed bed electrodialysis method for selective fluorine removal, the amount of ethylene glycol diallyl ether is 0.5 to 2.5 parts by weight.

[0027] Preferably, in a packed bed electrodialysis method for selective fluorine removal, the amount of N-methyldiallylamine used is 0.5 to 2.5 parts by weight.

[0028] Preferably, in a packed bed electrodialysis method for selective fluorine removal, the amount of 1,4-pentadien-3-ol used is 0.5 to 2.5 parts by weight.

[0029] More preferably, in a packed bed electrodialysis method for selective fluorine removal, the styrene-based monomer includes chloromethylstyrene, and the amount of chloromethylstyrene used is 80 to 120 parts by weight.

[0030] More preferably, the styrene-based monomer further comprises divinylbenzene, and the amount of divinylbenzene used is 4 to 8 parts by weight.

[0031] Preferably, in a packed bed electrodialysis method for targeted selective fluoride removal, the wastewater to be treated comprises an aqueous solution of chloride ions and an aqueous solution of fluoride ions.

[0032] More preferably, in a packed bed electrodialysis method for targeted selective fluorine removal, the concentration of fluoride ions is 1-30 mg / L.

[0033] More preferably, in a packed bed electrodialysis method for targeted selective fluorine removal, the concentration of chloride ions is 400-800 mg / L.

[0034] Preferably, a packed bed electrodialysis device for target selective fluorine removal comprises: a packed bed electrodialysis membrane stack, a pump control system, a water tank, a flow meter, an infusion pump and a pipeline.

[0035] Preferably, the packed bed electrodialysis membrane stack comprises: anion exchange membrane, cation exchange membrane, dilute chamber partition, concentrated chamber partition, electrode plates and clamping devices, which together constitute the dilute chamber, concentrated chamber and electrode chamber of the packed bed electrodialysis membrane stack.

[0036] Preferably, in the packed bed electrodialysis membrane stack, an anion exchange membrane, a cation exchange membrane and a partition constitute a circulation unit, and the anion exchange membrane and the cation exchange membrane are separated by the partition.

[0037] More preferably, the dilute chamber is filled with a filling material having high adsorption performance for fluoride ions, and the filling material is selected from hydroxy calcium phosphate, metal zirconium, aluminum oxide, and preferably at least one of a variety of amino, amide, and sulfone organic resins.

[0038] More preferably, the filling material is a cation exchange resin and an anion exchange resin.

[0039] More preferably, the anion exchange resin is selected from strong acid resins and strong base resins.

[0040] More preferably, the thickness of the partition of the dilute chamber is 2 to 15 length units, and the thickness of the partition of the dilute chamber can be determined according to the processing capacity of a single dilute chamber.

[0041] More preferably, the thickness of the partition of the concentration chamber is 2 to 15 length units, and the thickness of the partition of the concentration chamber can be determined according to the processing capacity of a single concentration chamber.

[0042] More preferably, the water inlet flow rate to the concentration chamber of the packed bed electrodialysis membrane stack is 2-20 L / h.

[0043] More preferably, the water inlet flow rate into the dilute chamber of the packed bed electrodialysis membrane stack is 2-20 L / h.

[0044] More preferably, the partition of the dilute chamber of the packed bed electrodialysis membrane stack is composed of a frame, on which there is a flow channel, the thickness of the partition is 0.9 to 2.0 length units, and the width of the channel is 0.1 to 0.5 length units.

[0045] More preferably, the concentrated chamber partition of the packed bed electrodialysis membrane stack is composed of a frame and a guide grid, there is a flow channel on the frame, the thickness of the partition is 0.9~2.0 length units, the diameter of the mesh of the guide grid is 0.05~0.15 length units, the inflow angle formed by the channel and the mesh is 20~80°, and the width of the channel is 0.1~0.5 length units.

[0046] More preferably, the anion exchange membrane is a heterogeneous ion membrane, the thickness of the anion exchange membrane is 0.3-0.6 length units, the exchange capacity of the anion exchange membrane is 1.2-2 mol / kg, and the selectivity for ions of the same charge is 85-100%.

[0047] More preferably, the cation exchange membrane is a heterogeneous ion membrane, the thickness of the cation exchange membrane is 0.3-0.6 length units, the exchange capacity of the cation exchange membrane is 1.2-2 mol / kg, and the selectivity for ions of the same charge is 85-100%.

[0048] Preferably, the pump circuit control system includes: a temperature sensor and a control system.

[0049] More preferably, the temperature sensor is connected to the control system and the pole chamber through a pipeline.

[0050] More preferably, the control system is connected to the dilute chamber, the concentrate chamber, the concentrate tank, the dilute water tank and the polar water tank through pipelines.

[0051] Preferably, the control system controls the operating parameters including voltage, current, concentrated chamber water inlet flow rate and dilute chamber water inlet flow rate;

[0052] More preferably, the temperature sensor is used to monitor the temperature change of the solution in the electrode chamber.

[0053] Preferably, the water tank comprises a concentrated water tank, a fresh water tank and an extreme water tank.

[0054] Preferably, the water tank is connected to the control system, the infusion pump and the flow meter through pipelines.

[0055] Preferably, the flowmeter is connected to the dilute chamber, the concentrated chamber, and the electrode chamber through pipelines, respectively, for detecting the flow rates of the dilute chamber, the concentrated chamber, and the electrode chamber.

[0056] Preferably, the water inlet end of the infusion pump is connected to the water tank, and the water outlet end is connected to the flow meter, so as to allow solutions in different compartments to circulate in respective pipelines through the packed bed electrodialysis membrane stack.

[0057] Preferably, in a packed bed electrodialysis device for target selective fluorine removal, the packed bed electrodialysis device is configured for segmented processing, and the number of stages is divided into 1 to 3.

[0058] More preferably, the first stage is carried out below the operating current to achieve the adsorption of fluoride ions in the filling material as much as possible, accompanied by the migration of a small amount of fluoride ions from the dilute chamber to the concentrated chamber.

[0059] More preferably, the second stage is carried out above the operating current, and the enriched fluoride ions are transferred to the concentration chamber by "desorption-migration", and the filling material is regenerated at the same time.

[0060] More preferably, a method for preparing a styrene resin comprises:

[0061] S1: Mix a styrene-based monomer, a diene compound, an initiator and a pore-forming agent, add a dispersant, and obtain an intermediate resin.

[0062] S2: Add an aminating agent to the intermediate resin and mix them to obtain a styrene resin.

[0063] Preferably, in the preparation method of the styrene resin, the styrene-based monomer is chloromethylstyrene, and the amount of chloromethylstyrene used is 80 to 120 parts by weight.

[0064] Preferably, in the preparation method of the styrene resin, the styrene-based monomer further includes divinylbenzene, and the amount of divinylbenzene used is 4 to 8 parts by weight.

[0065] Preferably, in the method for preparing the styrene resin, the diene compound is at least one of ethylene glycol diallyl ether, N-methyldiallylamine and 1,4-pentadien-3-ol.

[0066] More preferably, in the method for preparing the styrene resin, the diene compound is ethylene glycol diallyl ether.

[0067] More preferably, in the method for preparing the styrene resin, the diene compound is ethylene glycol diallyl ether and N-methyl diallylamine.

[0068] More preferably, in the method for preparing the styrene resin, the diene compound is ethylene glycol diallyl ether, N-methyldiallylamine and 1,4-pentadien-3-ol.

[0069] More preferably, in the method for preparing the styrene resin, the amount of ethylene glycol diallyl ether used is 0.5 to 2.5 parts by weight.

[0070] More preferably, in the method for preparing the styrene resin, the amount of N-methyldiallylamine used is 0.5 to 2.5 parts by weight.

[0071] More preferably, in the method for preparing the styrene resin, the amount of 1,4-pentadien-3-ol used is 0.5 to 2.5 parts by weight.

[0072] Preferably, in the method for preparing the styrene resin, the initiator is benzoyl peroxide, and the amount of benzoyl peroxide used is 0.2 to 0.8 parts by weight.

[0073] Preferably, in the preparation method of the styrene resin, the pore-forming agent is n-heptane, and the amount of n-heptane used is 8 to 12 parts by weight.

[0074] Preferably, in the method for preparing the styrene resin, the dispersant is a gelatin aqueous solution.

[0075] More preferably, in the preparation method of styrene resin, the mass fraction of gelatin in the aqueous solution is 1-3%, the amount of the gelatin aqueous solution is 400-600 parts by volume, wherein the amount relationship of chloromethylstyrene to the gelatin aqueous solution is 80-120g:400-600ml.

[0076] Preferably, in the method for preparing a styrene resin, the amount of the intermediate resin in S2 is 50 to 70 parts by weight. Preferably, in the method for preparing a styrene resin, the aminating agent is an aqueous solution of trimethylamine.

[0077] More preferably, the mass fraction of the trimethylamine aqueous solution is 27-35%, and the amount of the trimethylamine aqueous solution is 100-150 parts by volume. The amount of the intermediate resin and the trimethylamine aqueous solution is in the ratio of 50-70 g: 100-150 ml.

[0078] Preferably, in the method for preparing styrene resin, the reaction temperature in S2 is 28-32° C., and the reaction time is 14-18 h.

[0079] The present invention adopts styrene resin, and uses styrene resin as a strong base resin as a filling material added to a packed bed electrodialysis device for target selective fluorine removal. The present invention has low cost, simple operation steps, mild reaction conditions, and achieves efficient fluorine removal. Therefore, the present invention is a packed bed electrodialysis device and method for target selective fluorine removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 Schematic diagram of a packed bed electrodialysis unit for selective fluoride removal from groundwater.

[0081] Figure 2 Schematic diagram of the ion exchange resin filling method in the dilute chamber of a packed bed electrodialysis membrane stack.

[0082] The meanings of the numbers in the schematic diagram of the packed bed electrodialysis device for selective fluoride removal from groundwater are as follows: 1-dilute chamber, 2-concentrate chamber, 3-electrode chamber, 4-anion exchange membrane, 5-cation exchange membrane, 6-concentrate tank, 7-fresh water tank, 8-electrode tank, 9-flow meter, 10-infusion pump, 11-pipeline, 12-temperature sensor, 13-electrode plate, 14-cation exchange resin, 15-anion exchange resin, 16-control system. DETAILED DESCRIPTION

[0083] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0084] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0085] The packed bed electrodialysis device used in the present invention is as follows Figure 1 As shown, the packed bed electrodialysis device includes: a packed bed electrodialysis membrane stack, a pump control system, a water tank, a flow meter, an infusion pump and a pipeline.

[0086] The packed bed electrodialysis membrane stack includes: anion exchange membrane, cation exchange membrane, dilute chamber partition, concentrated chamber partition, electrode plate and clamping device, which together constitute the dilute chamber, concentrated chamber and electrode chamber of the packed bed electrodialysis membrane stack. Among them, the anion exchange membrane, cation exchange membrane and partition constitute the circulation unit in the packed bed electrodialysis membrane stack, the anion exchange membrane and the cation exchange membrane are separated by the partition, and the dilute chamber is filled with cation exchange resin and anion exchange resin.

[0087] The pump circuit control system includes: a temperature sensor and a control system. The temperature sensor is connected to the control system and the electrode chamber through pipelines; the control system is connected to the dilute chamber, the concentrated chamber, the concentrated water tank, the fresh water tank and the electrode water tank through pipelines.

[0088] The control system controls the operating parameters including voltage, current, concentrated chamber water inlet flow rate and dilute chamber water inlet flow rate, and the temperature sensor is used to monitor the temperature change of the cathode chamber solution.

[0089] The water tanks include a concentrated water tank, a fresh water tank and an extreme water tank, which are respectively connected to the control system, the infusion pump and the flow meter through pipelines.

[0090] The flowmeter is connected to the dilute chamber, the concentrated chamber and the electrode chamber through pipelines respectively, and is used to detect the flow rates of the dilute chamber, the concentrated chamber and the electrode chamber.

[0091] The water inlet end of the infusion pump is connected to the water tank, and the water outlet end is connected to the flow meter, so as to make the solutions of different compartments circulate in the respective pipelines through the packed bed electrodialysis membrane stack.

[0092] Among them, the partition thickness of the dilute chamber is 8mm, and the partition thickness of the concentrated chamber is 8mm.

[0093] The water inlet flow rate of the concentrated chamber of the packed bed electrodialysis membrane stack is 10 L / h; the water inlet flow rate of the dilute chamber of the packed bed electrodialysis membrane stack is 10 L / h.

[0094] The partition of the dilute chamber of the packed bed electrodialysis membrane stack is composed of a frame with a flow channel on the frame. The thickness of the partition is 1.6 mm and the width of the channel is 0.3 mm. The partition of the concentrated chamber of the packed bed electrodialysis membrane stack is composed of a frame and a guide grid. There is a flow channel on the frame. The thickness of the partition is 1.6 mm, the diameter of the mesh of the guide grid is 0.1 mm, the inlet angle formed by the channel and the mesh is 50°, and the width of the channel is 0.3 mm.

[0095] The anion exchange membrane is a heterogeneous ion membrane with a thickness of 0.4 mm, an exchange capacity of 1.6 mol / kg, and a selectivity of 90% for ions of the same charge; the cation exchange membrane is a heterogeneous ion membrane with a thickness of 0.4 mm, an exchange capacity of 1.6 mol / kg, and a selectivity of 90% for ions of the same charge.

[0096] The packed bed electrodialysis device is set up for segmented processing with two stages. The first stage is carried out below the operating current to achieve the adsorption of fluoride ions in the packing material as much as possible, accompanied by the migration of a small amount of fluoride ions from the dilute chamber to the concentrated chamber. The second stage is carried out above the operating current to achieve the migration of enriched fluoride ions to the concentrated chamber through "desorption-migration" and the regeneration of the packing material at the same time.

[0097] The ion exchange resin filling method in the desalination chamber of the packed bed electrodialysis membrane stack is as follows Figure 2 As shown, taking the present invention as an example, the dilute chamber of the packed bed electrodialysis membrane stack is filled with anion exchange resins, which are strong acid resins and strong base resins respectively. The filling method is mixed filling, and the optimized combination and filling are carried out according to the difference in properties of different anion exchange resins to improve the separation effect of fluoride ions.

[0098] Embodiment 1:

[0099] A conventional electrodialysis method for targeted selective fluoride removal.

[0100] The conventional electrodialysis membrane stack used has cation exchange membrane and anion exchange membrane alternately arranged between the anode and cathode plates, forming a double-layer woven mesh separator, and the cathode and anode plates are nail-coated materials. The operating current is 20mA. The conventional electrodialysis membrane stack has 3 cation membranes and 2 anion membranes. The double-layer woven mesh separator is the separator between the 2 concentrated chambers and 2 dilute chambers, and the thickness of each compartment is 8mm.

[0101] The electrodialysis time is 120 min, the concentration of fluoride ions in the dilute chamber is 2 mg / L, the concentration of chloride ions is 600 mg / L, and the inlet flow rate is 12 L / h; the concentration of fluoride ions in the concentrated chamber is 2 mg / L, the concentration of chloride ions is 600 mg / L, and the inlet flow rate is 6 L / h; the 0.1 mol / L sodium sulfate solution is used in the cathode chamber, and the inlet flow rate is 12 L / h. Constant current operation is adopted, and the applied current density is about 2.5 mA / cm 2 .

[0102] By using conventional electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.853 mg / L, and the chloride ion concentration dropped to 522.4 mg / L. The selective separation coefficient was 0.275.

[0103] Embodiment 2:

[0104] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0105] The difference between this embodiment and embodiment 1 is that the strong base resin and the strong acid resin are filled in the dilute chamber of the packed bed electrodialysis in proportion and operated, the dilute chamber of the packed bed electrodialysis has a partition without a woven mesh in the middle, which is used to fill the pretreated mixed bed resin. Apart from this, other conditions are the same as those in embodiment 1.

[0106] The ratio of strong base resin and strong acid resin filled in the dilute chamber is 1:1. The strong base resin is HP3500 and the dosage is 6.44 ml. The strong acid resin is D001 and the dosage is 6.44 ml. The filling degree is 40%. The dilute chamber partition of the packed bed electrodialysis is about 8 mm.

[0107] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.218 mg / L, the chloride ion concentration dropped to 574.325 mg / L, and the selective separation coefficient was -0.803.

[0108] Embodiment 3:

[0109] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0110] The difference between this embodiment and embodiment 2 is that the strong base resin filled is 550A. Apart from this, other conditions are the same as those of embodiment 2.

[0111] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.653 mg / L, the chloride ion concentration dropped to 425.143 mg / L, and the selective separation coefficient was 0.254.

[0112] Embodiment 4:

[0113] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0114] The difference between this embodiment and embodiment 2 is that the filling degree is 60%, the amount of strong base resin used is 9.66 ml, and other conditions are the same as those of embodiment 2.

[0115] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.175 mg / L, the chloride ion concentration dropped to 580.3 mg / L, and the selective separation coefficient was -0.853.

[0116] Embodiment 5:

[0117] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0118] Compared with Example 2, the difference between this example is that the filling degree is 80%, the amount of strong base resin used is 12.88 ml, and other conditions are the same as those of Example 2.

[0119] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.101 mg / L, the chloride ion concentration dropped to 584.245 mg / L, and the selective separation coefficient was -0.89.

[0120] Embodiment 6:

[0121] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0122] The difference between this embodiment and embodiment 2 is that the operating current is 30 mA. Other conditions are the same as those of embodiment 2.

[0123] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 0.831 mg / L, the chloride ion concentration dropped to 529.944 mg / L, and the selective separation coefficient was -0.667.

[0124] Embodiment 7:

[0125] A method for packed bed electrodialysis for targeted selective fluoride removal.

[0126] The difference between this embodiment and embodiment 2 is that the operating current is 50 mA. Other conditions are the same as those of embodiment 2.

[0127] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.303 mg / L, the chloride ion concentration dropped to 368.426 mg / L, and the selective separation coefficient was 0.051.

[0128] Embodiment 8:

[0129] A method for preparing styrene resin.

[0130] Chloromethylstyrene, divinylbenzene, benzoyl peroxide and n-heptane are mixed and placed in a reactor, stirred evenly, heated, gelatin aqueous solution is added, and a staged heating program reaction is started. After the reaction is completed, the mixture is cooled to room temperature, washed with methanol, and dried to obtain an intermediate resin. The amount of chloromethylstyrene is 100g, the amount of divinylbenzene is 6g, the amount of benzoyl peroxide is 0.5g, the amount of n-heptane is 10g, the stirring speed is 500r / min, the temperature is raised to 65°C, the mass fraction of gelatin in the aqueous solution is 2%, the amount of gelatin aqueous solution is 500ml, the staged heating program includes two heating and two insulations, the first heating to 85°C, the insulation time is 3h, the second heating to 98°C, the insulation time is 15h, the amount of methanol is 1000ml, the drying temperature is 35°C, and the drying time is 24h.

[0131] Add trimethylamine aqueous solution to the intermediate resin, mix, react under appropriate conditions, wash with methanol, and dry to obtain styrene resin. The amount of intermediate resin is 60g, the mass fraction of trimethylamine aqueous solution is 30%, the amount of trimethylamine aqueous solution is 120ml, the reaction temperature is 30℃, the reaction time is 16h, the amount of methanol is 500ml, the drying temperature is 35℃, and the drying time is 24h.

[0132] Embodiment 9:

[0133] A method for preparing styrene resin.

[0134] Compared with Example 8, the difference between this example is that ethylene glycol diallyl ether and N-methyl diallylamine are added during the preparation of the styrene resin. Other than that, the other conditions are the same as those of Example 8. Specifically:

[0135] Chloromethylstyrene, divinylbenzene, ethylene glycol diallyl ether, N-methyldiallylamine, benzoyl peroxide and n-heptane are mixed and placed in a reactor, stirred evenly, heated, and a gelatin aqueous solution is added to start a staged temperature increase program reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with methanol, and dried to obtain an intermediate resin. The amount of chloromethylstyrene is 100g, the amount of divinylbenzene is 6g, the amount of ethylene glycol diallyl ether is 1g, the amount of N-methyldiallylamine is 1g, the amount of benzoyl peroxide is 0.5g, the amount of n-heptane is 10g, the stirring speed is 500r / min, the temperature is raised to 65°C, the mass fraction of gelatin in the aqueous solution is 2%, the amount of gelatin aqueous solution is 500ml, the staged heating program includes two heating and two insulation, the first heating to 85°C, the insulation time is 3h, the second heating to 98°C, the insulation time is 15h, the amount of methanol is 1000ml, the drying temperature is 35°C, and the drying time is 24h.

[0136] Add trimethylamine aqueous solution to the intermediate resin, mix, react under appropriate conditions, wash with methanol, and dry to obtain styrene resin. The amount of intermediate resin is 60g, the mass fraction of trimethylamine aqueous solution is 30%, the amount of trimethylamine aqueous solution is 120ml, the reaction temperature is 30℃, the reaction time is 16h, the amount of methanol is 500ml, the drying temperature is 35℃, and the drying time is 24h.

[0137] Embodiment 10:

[0138] A method for preparing styrene resin.

[0139] Compared with Example 9, the difference between this example and Example 9 is that the amount of ethylene glycol diallyl ether and N-methyl diallylamine added in the preparation process of the styrene resin is 2 g. Apart from this, other conditions are the same as those in Example 9 to obtain a styrene resin.

[0140] Embodiment 11:

[0141] A method for preparing styrene resin.

[0142] The difference between this embodiment and embodiment 10 is that 1,4-pentadien-3-ol is added during the preparation of the styrene resin. Other than that, the other conditions are the same as those of embodiment 10. Specifically:

[0143] Chloromethylstyrene, divinylbenzene, ethylene glycol diallyl ether, N-methyldiallylamine, 1,4-pentadien-3-ol, benzoyl peroxide and n-heptane are mixed and placed in a reactor, stirred evenly, heated, and a gelatin aqueous solution is added to start a staged temperature increase program reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with methanol, and dried to obtain an intermediate resin. The amount of chloromethylstyrene used is 100g, the amount of divinylbenzene used is 6g, the amount of ethylene glycol diallyl ether used is 2g, the amount of N-methyldiallylamine used is 2g, the amount of 1,4-pentadien-3-ol used is 1g, the amount of benzoyl peroxide used is 0.5g, the amount of n-heptane used is 10g, the stirring speed is 500r / min, the temperature is raised to 65°C, the mass fraction of gelatin in the aqueous solution is 2%, the amount of gelatin aqueous solution used is 500ml, the staged heating program includes two heating and two insulations, the first heating to 85°C, the insulation time is 3h, the second heating to 98°C, the insulation time is 15h, the amount of methanol used is 1000ml, the drying temperature is 35°C, and the drying time is 24h.

[0144] Add trimethylamine aqueous solution to the intermediate resin, mix, react under appropriate conditions, wash with methanol, and dry to obtain styrene resin. The amount of intermediate resin is 60g, the mass fraction of trimethylamine aqueous solution is 30%, the amount of trimethylamine aqueous solution is 120ml, the reaction temperature is 30℃, the reaction time is 16h, the amount of methanol is 500ml, the drying temperature is 35℃, and the drying time is 24h.

[0145] Embodiment 12:

[0146] A method for preparing styrene resin.

[0147] The difference between this embodiment and embodiment 11 is that the amount of 1,4-pentadien-3-ol added in the preparation process of the styrene resin is 2 g. Apart from this, the other conditions are the same as those in embodiment 11 to obtain a styrene resin.

[0148] Comparative Example 1:

[0149] A method for preparing styrene resin.

[0150] Compared with Example 8, the difference between this embodiment is that ethylene glycol diallyl ether is added during the preparation of the styrene resin. Other than that, the other conditions are the same as those of Example 8. Specifically:

[0151] Chloromethylstyrene, divinylbenzene, ethylene glycol diallyl ether, benzoyl peroxide and n-heptane are mixed and placed in a reactor, stirred evenly, heated, gelatin aqueous solution is added, and a staged heating program is started for reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with methanol, and dried to obtain an intermediate resin. The amount of chloromethylstyrene is 100g, the amount of divinylbenzene is 6g, the amount of ethylene glycol diallyl ether is 1g, the amount of benzoyl peroxide is 0.5g, the amount of n-heptane is 10g, the stirring speed is 500r / min, the temperature is raised to 65°C, the mass fraction of gelatin in the aqueous solution is 2%, the amount of gelatin aqueous solution is 500ml, the staged heating program includes two heating and two insulations, the first heating to 85°C, the insulation time is 3h, the second heating to 98°C, the insulation time is 15h, the amount of methanol is 1000ml, the drying temperature is 35°C, and the drying time is 24h.

[0152] Add trimethylamine aqueous solution to the intermediate resin, mix, react under appropriate conditions, wash with methanol, and dry to obtain styrene resin. The amount of intermediate resin is 60g, the mass fraction of trimethylamine aqueous solution is 30%, the amount of trimethylamine aqueous solution is 120ml, the reaction temperature is 30℃, the reaction time is 16h, the amount of methanol is 500ml, the drying temperature is 35℃, and the drying time is 24h.

[0153] Comparative Example 2:

[0154] A method for preparing styrene resin.

[0155] Compared with Example 8, the difference between this example is that N-methyldiallylamine is added during the preparation of the styrene resin. Other than that, the other conditions are the same as those of Example 8. Specifically:

[0156] Chloromethylstyrene, divinylbenzene, N-methyldiallylamine, benzoyl peroxide and n-heptane are mixed and placed in a reactor, stirred evenly, heated, gelatin aqueous solution is added, and a staged heating program is started for reaction. After the reaction is completed, the mixture is cooled to room temperature, washed with methanol, and dried to obtain an intermediate resin. The amount of chloromethylstyrene is 100g, the amount of divinylbenzene is 6g, the amount of N-methyldiallylamine is 1g, the amount of benzoyl peroxide is 0.5g, the amount of n-heptane is 10g, the stirring speed is 500r / min, the temperature is raised to 65°C, the mass fraction of gelatin in the aqueous solution is 2%, the amount of gelatin aqueous solution is 500ml, the staged heating program includes two heating and two insulations, the first heating to 85°C, the insulation time is 3h, the second heating to 98°C, the insulation time is 15h, the amount of methanol is 1000ml, the drying temperature is 35°C, and the drying time is 24h.

[0157] Add trimethylamine aqueous solution to the intermediate resin, mix, react under appropriate conditions, wash with methanol, and dry to obtain styrene resin. The amount of intermediate resin is 60g, the mass fraction of trimethylamine aqueous solution is 30%, the amount of trimethylamine aqueous solution is 120ml, the reaction temperature is 30℃, the reaction time is 16h, the amount of methanol is 500ml, the drying temperature is 35℃, and the drying time is 24h.

[0158] Embodiment 13:

[0159] The only difference between this embodiment and embodiment 2 is that the strong base resin used for filling is the styrene resin prepared in embodiment 8. Other conditions are the same as those in embodiment 2.

[0160] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.182 mg / L, the chloride ion concentration dropped to 572.365 mg / L, and the selective separation coefficient was -0.798.

[0161] Embodiment 14:

[0162] The only difference between this embodiment and embodiment 2 is that the strong base resin used for filling is the styrene resin prepared in embodiment 9. Other conditions are the same as those in embodiment 9.

[0163] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.074 mg / L, the chloride ion concentration dropped to 573.221 mg / L, and the selective separation coefficient was -0.824.

[0164] Embodiment 15:

[0165] The only difference between this embodiment and embodiment 2 is that the strong base resin used for filling is the styrene resin prepared in embodiment 10. Other than that, the other conditions are the same as those in embodiment 2.

[0166] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 0.886 mg / L, the chloride ion concentration dropped to 574.576 mg / L, and the selective separation coefficient was -0.859.

[0167] Embodiment 16:

[0168] The only difference between this embodiment and embodiment 2 is that the strong base resin used for filling is the styrene resin prepared in embodiment 11. Other than that, the other conditions are the same as those in embodiment 2.

[0169] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 0.723 mg / L, the chloride ion concentration dropped to 575.652 mg / L, and the selective separation coefficient was -0.880.

[0170] Embodiment 17:

[0171] The only difference between this embodiment and embodiment 2 is that the strong base resin used for filling is the styrene resin prepared in embodiment 12. Other than that, the other conditions are the same as those in embodiment 2.

[0172] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 0.592 mg / L, the chloride ion concentration dropped to 577.412 mg / L, and the selective separation coefficient was -0.898.

[0173] Comparative Example 3:

[0174] The difference between this embodiment and embodiment 2 is that the strong base resin used as filling material is the styrene resin prepared in comparative example 1. Other than that, the other conditions are the same as those in embodiment 2.

[0175] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.176 mg / L, the chloride ion concentration dropped to 572.413 mg / L, and the selective separation coefficient was -0.799.

[0176] Comparative Example 4:

[0177] The difference between this embodiment and embodiment 2 is that the strong base resin used as filling material is the styrene resin prepared in comparative example 2. Other conditions are the same as those in embodiment 2.

[0178] By using packed bed electrodialysis, the fluoride ion concentration in the dilute chamber dropped to 1.164 mg / L, the chloride ion concentration dropped to 572.893 mg / L, and the selective separation coefficient was -0.805.

[0179] The selectivity separation factor ( ) for the same anion F in the IXED system - With Cl - The selective separation performance of A With components B The separation factor for:

[0180]

[0181] In the formula, A F - , B Cl - , F - and Cl - The selectivity separation coefficient between for t Time F- concentration; is the initial F - concentration; for t Moment Cl - concentration; is the initial Cl - concentration; The value range is -1~1. If F - Cl - If the transmission is slow, The value is between 0 and 1; if F - Cl - Fast transmission, Between -1 and 0.

[0182] Table 1 Electrodialysis treatment results

[0183]

[0184] As can be seen from Table 1, compared with Example 1 and Example 2, the packed bed electrodialysis method for removing fluoride ions is better than the conventional electrodialysis method, and the mixed bed resin filled in the dilute chamber has a certain promoting effect on the transmembrane migration of fluoride ions; compared with the experimental results of Examples 2-3 and Example 13, the fluoride ion concentration in Example 13 is relatively low, indicating that the selection of styrene resin as the strong base resin in the packed bed electrodialysis device is beneficial to improving the fluoride removal efficiency; compared with the experimental results of Examples 2 and Examples 4-5, the fluoride ion concentration in Example 5 is relatively low, indicating that the filling degree of the filling material in the packed bed electrodialysis device is 80%, which is more conducive to improving the fluoride removal efficiency; compared with the experimental results of Examples 2 and Examples 6-7, the fluoride ion concentration in Example 6 is relatively low, indicating that the operating current of the packed bed electrodialysis device is selected to be 30 mA is more conducive to improving the defluorination efficiency; comparing the experimental results of the three groups of Examples 13 to 15, the fluoride ion concentrations of the two groups of Examples 14 and 15 are relatively low, indicating that the participation of ethylene glycol diallyl ether and N-methyl diallyl amine in the preparation of styrene resin is beneficial to improving the defluorination efficiency of the packed bed electrodialysis device. At the same time, the higher the amount of ethylene glycol diallyl ether and N-methyl diallyl amine used, the more conducive it is to improving the defluorination efficiency of the packed bed electrodialysis device; comparing the experimental results of the five groups of Examples 13 to 17, the fluoride ion concentrations of the two groups of Examples 16 and 17 are relatively low. The concentration is relatively low, indicating that the participation of 1,4-pentadiene-3-ol in the preparation of styrene resin is beneficial to improving the defluorination efficiency of the packed bed electrodialysis device, and the higher the amount of 1,4-pentadiene-3-ol used, the more beneficial it is to improve the defluorination efficiency of the packed bed electrodialysis device; compared with the experimental results of Examples 13-14 and Comparative Examples 3-4, the fluoride ion concentration of Example 14 is lower, indicating that the participation of ethylene glycol diallyl ether alone or N-methyldiallylamine alone in the preparation of styrene resin is not conducive to improving the defluorination efficiency of the packed bed electrodialysis device. In addition, combined with the analysis of the concentration of chloride ions and the selective separation coefficient after the packed bed electrodialysis treatment, it is found that the selective separation coefficient of Example 7 is between 0 and 1, indicating that when the operating current of the packed bed electrodialysis device is 50 mA, the transmission rate of chloride ions in the device is faster than that of fluoride ions, which is not conducive to the defluorination of the packed bed electrodialysis device.

[0185] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention.

[0186] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for packed bed electrodialysis for target selective defluorination, comprising: The wastewater to be treated is treated by a packed bed electrodialysis device to obtain defluorinated treated water; the dilute chamber of the packed bed electrodialysis device is filled with a mixed bed resin, the mixed bed resin includes a strong base resin and a strong acid resin, the strong base resin is a styrene resin, and the styrene resin is prepared by reacting a diene compound including ethylene glycol diallyl ether and N-methyl diallylamine with a styrene-based monomer; The mixed volume ratio of the strong base resin and the strong acid resin in the mixed bed resin is 2:1-1:2, and the filling degree of the mixed bed resin is 20-100%; Styrene-based monomers include chloromethylstyrene and divinylbenzene.

2. A packed bed electrodialysis method for target selective defluorination according to claim 1, characterized in that: The wastewater to be treated includes a chloride ion aqueous solution and a fluoride ion aqueous solution.

3. A packed bed electrodialysis method for target selective fluorine removal according to claim 1, characterized in that: The usage of the strong base resin is 3 to 20 parts by volume.

4. A packed bed electrodialysis method for target selective defluorination according to claim 1, characterized in that: The preparation method of the styrene resin comprises: S1: Mix styrene-based monomer, diene compound, initiator and pore-forming agent, add dispersant to obtain intermediate resin, S2: Add an aminating agent to the intermediate resin and mix them to obtain a styrene resin.

5. The method of packed bed electrodialysis for target selective fluorine removal according to claim 1, characterized in that: The amount of chloromethylstyrene used is 80 to 120 parts by weight.

6. The method of packed bed electrodialysis for target selective defluorination according to claim 1, characterized in that: The divinylbenzene is used in an amount of 4 to 8 parts by weight.

7. A packed bed electrodialysis method for target selective defluorination according to claim 1, characterized in that: The diene compound is used in an amount of 0.5 to 2.5 parts by weight.

8. The method of packed bed electrodialysis for target selective defluorination according to claim 4, characterized in that: The dispersant is a gelatin aqueous solution, and the amount of the dispersant used is 400-600 parts by volume.

9. A packed bed electrodialysis method for target selective fluorine removal according to claim 8, characterized in that: The mass fraction of gelatin in the gelatin aqueous solution is 1-3%.

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