Gaseous membrane iodine extraction system and extraction method

Abstract

The invention discloses a gaseous membrane iodine extraction system and method in the technical field of iodine wastewater treatment, and aims to solve the problems of low efficiency and high energy consumption in iodine wastewater treatment in the prior art. The gaseous membrane iodine extraction system comprises a liquid feeding module, a gaseous membrane iodine extraction module and an iodine enrichment module; the gaseous membrane iodine extraction module comprises an iodine oxidation extraction unit, and the iodine oxidation extraction unit comprises a pipeline mixer, a preheating tank and a gaseous membrane iodine extraction device; the liquid feeding module is connected with a feed port of the pipeline mixer, a discharge port of the pipeline mixer is connected with a feed port of the preheating tank, a discharge port of the preheating tank is connected with a feed port of the gaseous membrane iodine extraction device, and the iodine enrichment device is connected with a gaseous membrane element of the gaseous membrane iodine extraction device. A discharge port of the gaseous membrane iodine extraction device is used for discharging iodine extraction water after iodine extraction; the method is suitable for extracting iodine in the high-concentration iodine-containing wastewater, and can realize the high-efficiency and low-energy-consumption recovery effect.

Description

Technical Field

[0001] This invention relates to the field of iodine wastewater treatment technology, and to a gaseous membrane iodine extraction system and method, particularly to a gaseous membrane iodine extraction system and method for high-concentration iodine-containing wastewater. Background Technology

[0002] Iodine is a key raw material in pharmaceutical synthesis, electronic component manufacturing, and fine chemicals, and is also an essential trace element for the human body. However, its natural resources are scarce and unevenly distributed. High-concentration iodine-containing wastewater (typically with an iodine content ≥500 mg / L) generated in industrial production is both a potential iodine resource and a source of pollution that urgently needs to be treated. Achieving efficient resource recovery from this wastewater has both economic value and environmental significance.

[0003] The sources of this type of high-concentration iodine-containing wastewater exhibit significant industry concentration: in the dyeing of polyvinyl alcohol membranes (PVA membranes) and the production of textile auxiliaries, the extensive use of iodine-based dyes and fixing agents directly discharges wastewater rich in potassium iodide (KI) and iodine (I2); in the pharmaceutical field, the incomplete reaction of raw materials and the separation process of intermediates during the synthesis of iodine contrast agents and antibacterial drugs generate high-concentration iodine-containing mother liquor; in the iodine chemical and pesticide production processes, the excessive addition of iodide raw materials also forms high-concentration iodine-containing wastewater; in addition, the concentrated liquid obtained after low-concentration iodine-containing wastewater is concentrated by systems such as reverse osmosis and nanofiltration also constitutes an important source of high-concentration iodine-containing wastewater.

[0004] Currently, the mainstream extraction processes for iodine-containing wastewater are mainly traditional methods, including stripping, ion exchange, and solvent extraction. Stripping involves introducing a carrier gas into the acidified and oxidized wastewater to strip off gaseous iodine, which is then recovered using an absorbent. Ion exchange utilizes the selective adsorption of iodide ions by resins to achieve separation. Solvent extraction involves mixing and separating organic solvents with iodine-containing wastewater to achieve iodine phase transfer.

[0005] However, these traditional processes face numerous insurmountable bottlenecks when applied to the treatment of high-concentration iodine-containing wastewater: The stripping method requires a large amount of carrier gas to maintain mass transfer, resulting in extremely high energy consumption; furthermore, flooding and channeling easily occur during gas-liquid contact, leading to an iodine recovery rate of only 70%-85%, and unrecovered iodine leaking with the tail gas can cause secondary pollution; in the ion exchange method, high-concentration wastewater easily saturates the resin rapidly, requiring a regeneration frequency of 1-2 times per week, resulting in high regenerant consumption, and the resin is susceptible to coexisting Cl-... - SO4 2- Poor selectivity for impurities affects product purity; organic solvents in solvent extraction are prone to volatilization and loss, posing a fire risk; and the back-extraction process of the extract is complex, requiring additional treatment of the waste liquid, resulting in significant environmental pressure.

[0006] To address the aforementioned issues, there is an urgent need to develop an extraction technology that combines high recovery rate, high selectivity, low energy consumption, and environmental friendliness to meet the treatment requirements of high-concentration iodine-containing wastewater, achieve efficient recovery of iodine resources and compliant discharge of wastewater, and promote technological upgrading in the field of iodine-containing wastewater treatment. Summary of the Invention

[0007] The purpose of this invention is to provide a gaseous membrane iodine extraction system to achieve high recovery rate, high efficiency, and low cost in extracting iodine from wastewater, while reducing the footprint and improving the iodine extraction efficiency of the device.

[0008] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0009] On one hand, the present invention provides a gaseous membrane iodine extraction system, including a liquid delivery module, a gaseous membrane iodine extraction module, and an iodine enrichment module;

[0010] The gaseous membrane iodine extraction module includes at least one stage of iodine oxidation extraction unit, which includes a pipeline mixer, a preheating tank, and a gaseous membrane iodine extraction device.

[0011] The liquid delivery module is connected to the inlet of the pipeline mixer, the outlet of the pipeline mixer is connected to the inlet of the preheating tank, the outlet of the preheating tank is connected to the inlet of the gaseous membrane iodine extraction device, the iodine enrichment module is connected to the gaseous membrane element of the gaseous membrane iodine extraction device, and the outlet of the gaseous membrane iodine extraction device is used to discharge the iodine extraction water after iodine extraction.

[0012] In the above technical solution, the liquid delivery module is used to transport iodine-containing wastewater to the gaseous membrane iodine extraction module; the gaseous membrane iodine extraction module is used to extract iodine from the iodine-containing wastewater and then separate the extracted elemental iodine through the gaseous membrane before transporting it to the iodine enrichment module; the iodine enrichment module is used to adjust the vacuum and enrich elemental iodine.

[0013] The pipeline mixer of the gaseous membrane iodine extraction module is used to fully mix the iodine-containing wastewater with the oxidant and then transport the mixed product water to the preheating tank, where iodide ions are oxidized into elemental iodine. The preheating tank is used to heat the mixed product water and then transport the heated mixed product water to the gaseous membrane iodine extraction device, where the elemental iodine is vaporized into iodine molecules. The gaseous membrane iodine extraction device is used to receive the iodine extraction product water containing vaporized iodine molecules and separate it into gaseous iodine molecules and liquid iodine extraction product water through the gaseous membrane. The gaseous iodine molecules enter the iodine enrichment module, while the iodine extraction product water is discharged.

[0014] Compared to traditional tower-type stripping + absorption iodine separation devices, the above-mentioned technical solution uses a gaseous membrane iodine extraction system that does not require a large amount of carrier gas (air or nitrogen), has a smaller absorption liquid circulation volume, and features a modular design for the membrane components, which can reduce the floor space required. In the iodine separation section, the use of a multi-stage oxidation + gaseous membrane iodine extraction unit combination can significantly improve the iodine ion oxidation rate and iodine recovery rate.

[0015] Furthermore, the gaseous membrane iodine extraction module includes 2 to 6 stages of iodine oxidation extraction units.

[0016] In the above technical solution, the gaseous membrane iodine extraction device separates the iodine-extracting water containing gaseous iodine molecules into iodine molecules and iodine-extracting water. The gaseous iodine molecules enter the iodine enrichment module, and the iodine-extracting water enters the pipeline mixer of the next stage iodine oxidation extraction unit. The iodine-extracting water of the gaseous membrane iodine extraction device of the last stage gaseous membrane iodine extraction unit is discharged.

[0017] Iodine-containing wastewater enters the pipeline mixer from the liquid delivery module. After thorough mixing and reaction with the oxidant in the pipeline mixer, it enters the preheating tank. Here, iodide ions are oxidized to elemental iodine. In the preheating tank, the iodine is heated and transported to the tube side of the gaseous membrane iodine extraction device. Iodine molecules pass through the gaseous membrane and enter the shell side of the gaseous membrane element, achieving separation of iodine molecules and the iodine-extracting wastewater—that is, separating iodine molecules from the wastewater. To improve iodine recovery, a multi-stage iodine oxidation extraction unit is used. The iodine-extracting wastewater from the first-stage iodine oxidation extraction unit enters the subsequent pipeline mixer for oxidation, and is then extracted and separated by the subsequent gaseous membrane iodine extraction device. Finally, the iodine-extracting wastewater is discharged, while the iodine molecules enter the iodine enrichment module.

[0018] The iodine oxidation extraction unit with stages 2 to 6 can maximize the extraction of iodine from wastewater and reduce unnecessary extraction losses.

[0019] Furthermore, the gaseous membrane iodine extraction module also includes a heat exchanger connected between the two iodine oxidation extraction units.

[0020] The heat exchanger's inlet is connected to the liquid outlet of the gaseous membrane iodine extraction device of the preceding iodine oxidation extraction unit, and the cooled iodine-extracting water is transported to the inlet of the pipeline mixer of the subsequent gaseous membrane iodine extraction device.

[0021] In the above technical solution, the heat exchanger is used to cool the iodine-extracting water extracted by the gaseous membrane iodine extraction device of the previous stage iodine oxidation extraction unit, and to transport the cooled iodine-extracting water to the pipeline mixer of the gaseous membrane iodine extraction device of the adjacent next stage iodine oxidation extraction unit for secondary oxidation.

[0022] In the iodine separation section, a heat exchange device is added between the two-stage iodine oxidation extraction units. This device cools the water produced in the previous stage while increasing the temperature of the iodine vapor, thus preventing the loss of oxidant at high temperatures and ensuring the overall iodine oxidation rate.

[0023] Furthermore, the iodine enrichment module includes an absorption liquid mixing tank, a circulation pump, an ejector, and a vacuum control valve;

[0024] The circulation outlet of the absorbent mixing tank is connected to the inlet of the circulation pump, the outlet of the circulation pump is connected to the inlet of the ejector, the air inlet of the ejector is connected to the gaseous membrane element of the gaseous membrane iodine extraction device of the final extraction stage of the iodine oxidation extraction unit, and the outlet of the ejector is connected to the circulation inlet of the absorbent circulation tank; the vacuum control valve is connected to the gaseous membrane element of the gaseous membrane iodine extraction device of the iodine oxidation extraction unit.

[0025] In the above technical solution, the absorbent mixing tank is used to store the absorbent; the circulating pump is used to transport the absorbent in the absorbent mixing tank to the ejector; the ejector is used to receive the elemental iodine separated by the gaseous membrane iodine extraction device, and to transport the elemental iodine and the absorbent back to the absorbent mixing tube for absorption and circulation; the vacuum control valve is used to control the vacuum degree of the gaseous membrane iodine extraction device, so that iodine molecules enter the iodine enrichment module under negative pressure. The circulation chamber of the ejector and the gaseous membrane element of the gaseous membrane iodine extraction device form a closed loop cavity. The vacuum control valve is installed on the gaseous membrane element of the gaseous membrane iodine extraction device. The vacuum degree of the gaseous membrane iodine extraction device can be adjusted by controlling the flow rate of the ejector and the vacuum control valve in synergy.

[0026] The iodine absorbent is transported from the absorbent mixing tank to the ejector via a circulating pump. The ejector is connected to a gaseous membrane element. By adjusting the vacuum control valve, the vacuum in the shell side of the gaseous membrane element is controlled, so that iodine molecules enter the ejector under negative pressure and mix thoroughly with the absorbent, ultimately achieving the enrichment of iodine in the absorbent.

[0027] In the iodine absorption section, the jet device can be used to adjust the vacuum level of the gas membrane shell of the gas membrane iodine extraction device by controlling the circulation volume of the absorption liquid and the opening and closing degree of the vacuum valve. This can better achieve full mixing of iodine vapor and absorption liquid, improve the absorption rate, and reduce the volume of the alkali absorption tank.

[0028] Furthermore, the preheating tank is provided with packing material, which includes one or a combination of polyvinylidene fluoride, polytetrafluoroethylene, and polypropylene.

[0029] Furthermore, the gaseous membrane material of the gaseous membrane iodine extraction device includes one of polyvinylidene fluoride, polytetrafluoroethylene, and polypropylene.

[0030] Furthermore, the pipe mixer is a pipe mixer with 3 to 10 sections.

[0031] In the above technical solution, the 3-10 section pipe mixer can achieve full mixing and oxidation of iodine-containing wastewater.

[0032] Furthermore, the liquid delivery module includes an iodine-containing material storage tank and a waste liquid transfer pump;

[0033] The outlet of the iodine-containing material storage tank is connected to the inlet of the waste liquid transfer pump, and the outlet of the waste liquid transfer pump is connected to the inlet of the pipeline mixer.

[0034] In the above technical solution, the iodine-containing material storage tank is used to store iodine-containing wastewater; the waste liquid transfer pump is used to transport the iodine-containing wastewater in the iodine-containing material storage tank to the gaseous membrane iodine extraction module.

[0035] Furthermore, the pipeline mixer is provided with an oxidant, which includes one or more of chlorine, sodium hypochlorite, sodium perchlorate, chlorine dioxide, hydrogen peroxide, and potassium permanganate.

[0036] Furthermore, the absorbent mixing tank contains an absorbent, which includes one or more of sodium hydroxide, potassium hydroxide, ammonia, calcium hydroxide, magnesium hydroxide, and sodium sulfite.

[0037] On the other hand, the present invention provides a gaseous membrane iodine extraction method, based on the gaseous membrane iodine extraction system described in any of the foregoing claims, comprising the following steps:

[0038] The iodine-containing wastewater is transported by the liquid delivery module to the pipeline mixer for mixing to obtain mixed product water;

[0039] The mixed permeate is transported to a preheating tank and heated under preset heating conditions to obtain iodine-extracting permeate containing vaporized iodine molecules;

[0040] The iodine-extraction water containing vaporized iodine molecules is transported to the gas membrane iodine extraction device (5) and gas-liquid separation is carried out at the gas membrane interface according to the preset separation conditions to obtain vaporized iodine molecules;

[0041] Vaporized iodine molecules are transported to an iodine enrichment module under vacuum conditions for enrichment, thus obtaining extracted iodine.

[0042] In the above technical solution, the iodine extraction water containing vaporized iodine molecules undergoes gas-liquid separation at the gas membrane interface. The vaporized iodine molecules diffuse through the gas membrane filaments into the shell side of the gas membrane iodine extraction device, where they are separated from the iodine extraction water. The vaporized iodine molecules in the shell side diffuse into the iodine enrichment module under vacuum conditions and are collected by the absorbent in the iodine enrichment module.

[0043] Furthermore, the gaseous membrane iodine extraction method also includes transporting the iodine-extracting water from the previous stage to a heat exchanger, cooling the iodine-extracting water according to preset heat exchange conditions, and then transporting the cooled iodine-extracting water to the next stage pipeline reactor for further oxidation of iodine ions.

[0044] Furthermore, the vacuum condition is that the vacuum degree of the shell side of the gaseous membrane element of the gaseous membrane iodine extraction device is controlled at 0.01~0.1MPa.

[0045] In the above technical solution, the iodine absorbent is transported from the absorbent mixing tank to the ejector via a circulation pump. The ejector is connected to the gas outlet of the gas membrane iodine extraction device. By controlling the circulation volume of the absorbent and the opening and closing degree of the vacuum valve, the vacuum of the gas membrane shell side of the gas membrane iodine extraction device is controlled in a coordinated manner, so that iodine molecules enter the ejector under negative pressure and are fully mixed with the absorbent, ultimately achieving the enrichment of iodine in the absorbent.

[0046] Furthermore, the molar ratio of the oxidant to iodine is (1~4):1.

[0047] Furthermore, the preset heating conditions are: the temperature of the preheating tank is controlled at 40~80℃, and the preheating residence time is 0.5~2h.

[0048] Furthermore, the preset separation conditions are as follows: the flow rate of the iodine extraction product containing gasified iodine molecules in the tube side of the gas membrane iodine extraction device is controlled at 0.05~0.5m / s.

[0049] Furthermore, the preset heat exchange conditions are: the temperature of the iodine extraction water controlled by the heat exchanger is 20~40℃.

[0050] Furthermore, the extraction method of the gaseous membrane iodine extraction system also includes setting the circulation rate of the absorption liquid to 15-25 times / hour.

[0051] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0052] Compared to traditional tower-type stripping and absorption iodine separation units, the gaseous membrane system does not require a large amount of carrier gas (air or nitrogen), has a smaller absorption liquid circulation volume, and the membrane module has a modular design, which can reduce the footprint. In the iodine separation section, the use of a multi-stage oxidation + gaseous membrane combination unit can significantly improve the iodide ion oxidation rate and iodine recovery rate.

[0053] A heat exchange device is added between the two stages to cool the water produced in the previous stage while raising the temperature of the iodine vapor, thus avoiding the loss of oxidant at high temperatures and ensuring the overall iodine oxidation rate.

[0054] In the iodine absorption section, a jet device is used to control the vacuum level of the gaseous membrane shell by controlling the circulation rate of the absorbent liquid and the opening and closing degree of the vacuum valve, so as to achieve full mixing of iodine vapor and alkali absorbent liquid, improve the absorption rate, and reduce the volume of the alkali absorption tank. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a schematic diagram of the structure of some embodiments of the gaseous membrane iodine extraction system and extraction method provided by the present invention.

[0057] Explanation of reference numerals in the attached figures:

[0058] 1. Iodine-containing material storage tank; 2. Waste liquid transfer pump; 3. Pipeline mixer; 4. Preheating tank; 5. Gas membrane iodine extraction device; 6. Heat exchanger; 7. Vacuum control valve; 8. Ejector; 9. Circulation pump; 10. Absorbent liquid mixing tank. Detailed Implementation

[0059] The above content is further illustrated below with specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments. All technologies implemented based on the above content of this invention fall within the scope of this invention.

[0060] It should be understood that all experimental procedures not detailed in the experiment are routine experimental procedures well known to those skilled in the art.

[0061] Example 1

[0062] This embodiment provides a gaseous membrane iodine extraction system, including a liquid delivery module, a gaseous membrane iodine extraction module, and an iodine enrichment module;

[0063] The gaseous membrane iodine extraction module includes a two-stage iodine oxidation extraction unit, such as... Figure 1 As shown, each stage of iodine oxidation extraction unit includes a pipeline mixer 3, a preheating tank 4, and a gaseous membrane iodine extraction device 5;

[0064] The liquid delivery module is connected to the inlet of the pipeline mixer 3, the outlet of the pipeline mixer 3 is connected to the inlet of the preheating tank 4, the outlet of the preheating tank 4 is connected to the inlet of the gaseous membrane iodine extraction device 5, the iodine enrichment module is connected to the gaseous outlet of the gaseous membrane iodine extraction device 5, the liquid outlet of the gaseous membrane iodine extraction device 5 is connected to the inlet of the pipeline mixer 3 of the adjacent first-stage iodine oxidation extraction unit, and the liquid outlet of the gaseous membrane iodine extraction device 5 of the last-stage iodine oxidation extraction unit is used to discharge the material.

[0065] Example 2

[0066] This embodiment provides a gaseous membrane iodine extraction system, such as Figure 1As shown, it includes an iodine-containing material storage tank 1, a waste liquid transfer pump 2, a gaseous membrane iodine extraction module, a heat exchanger 6, an absorption liquid mixing tank 10, a circulation pump 9, an ejector 8, and a vacuum control valve 7.

[0067] The gaseous membrane iodine extraction module includes three iodine oxidation extraction units. Each iodine oxidation extraction unit includes a pipeline mixer 3, a preheating tank 4, and a gaseous membrane iodine extraction device 5. Heat exchangers 6 are respectively arranged between the first and second stages and between the second and third stages of the iodine oxidation extraction units.

[0068] The outlet of the iodine-containing material storage tank 1 is connected to the inlet of the waste liquid transfer pump 2, and the outlet of the waste liquid transfer pump 2 is connected to the inlet of the pipeline mixer 3.

[0069] The outlet of the pipeline mixer 3 is connected to the inlet of the preheating tank 4, the outlet of the preheating tank 4 is connected to the inlet of the gaseous membrane iodine extraction device 5, the outlet of the gaseous membrane iodine extraction device 5 is connected to the inlet of the heat exchanger 6, the outlet of the heat exchanger 6 is connected to the inlet of the pipeline mixer 3 of the adjacent first-stage iodine oxidation extraction unit, and the outlet of the gaseous membrane iodine extraction device 5 of the third-stage iodine oxidation extraction unit is used to discharge the material.

[0070] The circulation outlet of the absorbent mixing tank 10 is connected to the inlet of the circulation pump 9, the outlet of the circulation pump 9 is connected to the inlet of the ejector 8, and the outlet of the ejector 8 is connected to the circulation inlet of the absorbent circulation tank; the vacuum control valve 7 is connected to the gaseous membrane element of the gaseous membrane iodine extraction device 5 of the first-stage iodine oxidation extraction unit, and the air inlet of the ejector 8 is connected to the gaseous membrane element of the gaseous membrane iodine extraction device 5 of the third-stage iodine oxidation extraction unit.

[0071] Example 3

[0072] This embodiment provides a gaseous membrane iodine extraction system, such as Figure 1 As shown, it includes an iodine-containing material storage tank 1, a waste liquid transfer pump 2, a gaseous membrane iodine extraction module, a heat exchanger 6, an absorption liquid mixing tank 10, a circulation pump 9, an ejector 8, and a vacuum control valve 7.

[0073] The gaseous membrane iodine extraction module includes a 6-stage iodine oxidation extraction unit. Each stage of the iodine oxidation extraction unit includes a pipeline mixer 3, a preheating tank 4, and a gaseous membrane iodine extraction device 5. Heat exchangers 6 are respectively arranged between the front and rear stages of the iodine oxidation extraction unit.

[0074] The outlet of the iodine-containing material storage tank 1 is connected to the inlet of the waste liquid transfer pump 2, and the outlet of the waste liquid transfer pump 2 is connected to the inlet of the pipeline mixer 3.

[0075] The outlet of the pipeline mixer 3 is connected to the inlet of the preheating tank 4, the outlet of the preheating tank 4 is connected to the inlet of the gaseous membrane iodine extraction device 5, the outlet of the gaseous membrane iodine extraction device 5 is connected to the inlet of the heat exchanger 6, the outlet of the heat exchanger 6 is connected to the inlet of the pipeline mixer 3 of the adjacent iodine oxidation extraction unit, and the outlet of the gaseous membrane iodine extraction device 5 of the sixth-stage iodine oxidation extraction unit is used to discharge the material.

[0076] The circulation outlet of the absorption liquid mixing tank 10 is connected to the inlet of the circulation pump 9, the outlet of the circulation pump 9 is connected to the inlet of the ejector 8, and the outlet of the ejector 8 is connected to the circulation inlet of the absorption liquid circulation tank; the vacuum control valve 7 is connected to the gaseous membrane element of the gaseous membrane iodine extraction device 5 of the first-stage iodine oxidation extraction unit, and the air inlet of the ejector 8 is connected to the gaseous membrane element of the gaseous membrane iodine extraction device 5 of the sixth-stage iodine oxidation extraction unit.

[0077] Example 4

[0078] This embodiment provides an extraction method for the gaseous membrane iodine extraction system of Example 2, including the following steps:

[0079] Iodine-containing wastewater is added to iodine-containing material storage tank 1, oxidant is added to pipeline mixer 3, and absorbent is added to absorbent mixing tank 10.

[0080] Turn on waste liquid transfer pump 2; turn on preheating tank 4, adjust the temperature of the heating tank to 40℃, and set the preheating residence time to 1h; turn on gaseous membrane iodine extraction device 5, and control the flow rate of the material in the tube side of gaseous membrane iodine extraction device 5 to 0.2m / s.

[0081] Turn on heat exchanger 6 and set the temperature to 25℃;

[0082] Adjust the vacuum control valve 7 to control the vacuum level of the gaseous membrane shell to -0.075MPa; adjust the temperature of the absorbent in the absorbent mixing tank 10 to 40℃; adjust the circulation pump 9 to control the circulation rate of the absorbent to 15 times / hour.

[0083] The iodide ion concentration in the iodine-containing wastewater was 1454 mg / L, and the total dissolved salt content was 125 g / L. Hydrogen peroxide was used as the oxidant, with a hydrogen peroxide addition ratio of H2O2:I molar ratio of 4:1. Sodium hydroxide was used as the absorbent.

[0084] Among them, the pipeline mixer 3 adopts a 3-section pipeline mixer 3; the preheating tank 4 is filled with packing material made of polyvinylidene fluoride (PVDF); the gaseous membrane iodine extraction module adopts a 3-stage iodine oxidation extraction unit; the gaseous membrane element of the gaseous membrane iodine extraction device 5 is made of PVDF-based modified membrane.

[0085] The extraction process for iodine-containing wastewater is as follows:

[0086] Iodine-containing wastewater is transported from iodine-containing material storage tank 1 to waste liquid transfer pump 2, and then fully mixed with oxidant in pipeline mixer 3. The mixed product water enters preheating tank 4 and stays in preheating tank 4 at 40°C for 1 hour. During this time, iodide ions in the mixed product water are fully oxidized into elemental iodine. The mixed liquid containing elemental iodine is transported from preheating tank 4 to the tube side of gaseous membrane iodine extraction device 5. Iodine molecules diffuse through the membrane filaments of the gaseous membrane into the shell side of the gaseous membrane element, realizing the separation of iodine molecules and waste liquid (iodine extraction product water).

[0087] This project adopts a three-stage iodine oxidation extraction unit. The iodine-extracting water from the first-stage iodine oxidation extraction unit is cooled by heat exchanger 6. Heat exchanger 6 controls the water temperature to below 25°C. The water then enters the next-stage pipeline mixer 3 for oxidation and the next-stage gaseous membrane iodine extraction device 5 for extraction. Finally, the iodine-extracting water is discharged.

[0088] Iodine absorbent is transported from absorbent mixing tank 10 to ejector 8 via circulating pump 9. Ejector 8 is connected to gaseous membrane element. The vacuum degree of the shell side of gaseous membrane element is controlled at -0.075MPa by adjusting vacuum control valve 7, so that iodine molecules enter ejector 8 under negative pressure and are fully mixed with absorbent. Sodium hydroxide is used as absorbent, the temperature of absorbent is controlled at 40℃, and the circulation rate of absorbent is controlled at 15 times / hour, so as to achieve iodine enrichment in absorbent.

[0089] After the above-mentioned three-stage oxidation extraction unit, three-stage pipeline mixer 3 oxidation and three-stage gas membrane iodine extraction device 5 extraction, the iodine ion concentration in the iodine product water is 102 mg / L, and the iodine ion recovery rate reaches 92.9%.

[0090] Example 5

[0091] This embodiment provides an extraction method for the gaseous membrane iodine extraction system of Example 2, including the following steps:

[0092] Iodine-containing wastewater is added to iodine-containing material storage tank 1, oxidant is added to pipeline mixer 3, and absorbent is added to absorbent mixing tank 10.

[0093] Turn on waste liquid transfer pump 2; turn on preheating tank 4, adjust the temperature of the heating tank to 50℃, and set the preheating residence time to 1h; turn on gaseous membrane iodine extraction device 5, and control the flow rate of the material in the tube side of the gaseous membrane element of gaseous membrane iodine extraction device 5 to 0.2m / s.

[0094] Turn on heat exchanger 6 and set the temperature to 20℃;

[0095] Adjust the vacuum control valve 7 to control the vacuum level of the shell side of the gaseous membrane element to -0.075MPa; adjust the temperature of the absorbent in the absorbent mixing tank 10 to 40℃; adjust the circulation pump 9 to control the circulation rate of the absorbent to 15 times / hour.

[0096] The iodide ion concentration in the iodine-containing wastewater was 1454 mg / L, and the total dissolved salt content was 125 g / L. Chlorine was used as the oxidant, with a chlorine addition ratio of Cl2:I molar ratio of 1:1. Sodium hydroxide was used as the absorbent.

[0097] Among them, the pipeline mixer 3 adopts a 3-section pipeline mixer 3; the preheating tank 4 is filled with packing material made of polytetrafluoroethylene (PTFE); the gaseous membrane iodine extraction module adopts a 3-stage iodine oxidation extraction unit; the gaseous membrane element of the gaseous membrane iodine extraction device 5 is made of PTFE-based modified membrane.

[0098] The extraction process for iodine-containing wastewater is as follows:

[0099] Iodine-containing wastewater is transported from iodine-containing material storage tank 1 to waste liquid transfer pump 2, and then fully mixed with oxidant in pipeline mixer 3. The mixed product water enters preheating tank 4 and stays in preheating tank 4 at 40°C for 1 hour. During this time, iodide ions are oxidized to elemental iodine. The elemental iodine is then heated in preheating tank 4 and transported to the tube side of gaseous membrane iodine extraction device 5, where it is converted into gaseous iodine molecules. These molecules then pass through the gaseous membrane and enter the shell side of the gaseous membrane element, thus achieving the separation of iodine molecules and wastewater.

[0100] This project adopts a three-stage iodine oxidation extraction unit. The iodine-extracting water from the first-stage iodine oxidation extraction unit is cooled by heat exchanger 6. Heat exchanger 6 controls the water temperature to below 25°C. The water then enters the next-stage pipeline mixer 3 for oxidation and the next-stage gaseous membrane iodine extraction device 5 for extraction. Finally, the iodine-extracting water is discharged.

[0101] Iodine absorbent is transported from absorbent mixing tank 10 to ejector 8 via circulating pump 9. Ejector 8 is connected to gaseous membrane element. The vacuum degree of the shell side of gaseous membrane element is controlled at -0.075MPa by adjusting vacuum control valve 7, so that iodine molecules enter ejector 8 under negative pressure and are fully mixed with absorbent. Sodium hydroxide is used as absorbent, the temperature of absorbent is controlled at 40℃, and the circulation rate of absorbent is controlled at 15 times / hour, so as to achieve iodine enrichment in absorbent.

[0102] After the above-mentioned three-stage oxidation extraction unit, three-stage pipeline mixer 3 oxidation and three-stage gas membrane iodine extraction device 5 extraction, the iodine ion concentration in the iodine product water is 138 mg / L, and the iodine ion recovery rate reaches 90.5%.

[0103] Example 6

[0104] This embodiment provides an extraction method for the gaseous membrane iodine extraction system of Example 3, including the following steps:

[0105] Iodine-containing wastewater is added to iodine-containing material storage tank 1, oxidant is added to pipeline mixer 3, and absorbent is added to absorbent mixing tank 10.

[0106] Turn on waste liquid transfer pump 2; turn on preheating tank 4, adjust the temperature of the heating tank to 40℃, and set the preheating residence time to 2h; turn on gaseous membrane iodine extraction device 5, and control the flow rate of the material in the tube side of the gaseous membrane element of gaseous membrane iodine extraction device 5 to 0.5m / s.

[0107] Turn on heat exchanger 6 and set the temperature to 23℃;

[0108] Adjust the vacuum control valve 7 to control the vacuum level of the gaseous membrane element shell to -0.085MPa; adjust the temperature of the absorbent in the absorbent mixing tank 10 to 40℃; adjust the circulation pump 9 to control the circulation rate of the absorbent to 25 times / hour.

[0109] The iodide ion concentration in the iodine-containing wastewater was 4845 mg / L, and the total dissolved salt content was 214 g / L. Hydrogen peroxide was used as the oxidant, with a hydrogen peroxide addition ratio of H2O2:I molar ratio of 2:1. Sodium hydroxide was used as the absorbent.

[0110] Among them, the pipeline mixer 3 adopts an 8-section pipeline mixer 3; the preheating tank 4 is filled with packing material made of PVDF; the gaseous membrane iodine extraction module adopts a 6-stage iodine oxidation extraction unit; the gaseous membrane element of the gaseous membrane iodine extraction device 5 is made of a modified membrane with PVDF substrate.

[0111] The extraction process for iodine-containing wastewater is as follows:

[0112] Iodine-containing wastewater is transported from iodine-containing material storage tank 1 to waste liquid transfer pump 2, and then fully mixed with oxidant in pipeline mixer 3. The mixed product water enters preheating tank 4 and stays in preheating tank 4 at 40°C for 2 hours. During this time, iodide ions are oxidized to elemental iodine. The elemental iodine is then heated in preheating tank 4 and transported to the tube side of gaseous membrane iodine extraction device 5, where it is converted into gaseous iodine molecules. These molecules then pass through the gaseous membrane and enter the shell side of the gaseous membrane element, thus achieving the separation of iodine molecules and wastewater.

[0113] This project adopts a 6-stage iodine oxidation extraction unit. The iodine-extracting water from the first-stage iodine oxidation extraction unit is cooled by heat exchanger 6. Heat exchanger 6 controls the water temperature to below 25°C. Then, it enters the next-stage pipeline mixer 3 for oxidation and the next-stage gaseous membrane iodine extraction device 5 for extraction. Finally, the iodine-extracting water is discharged.

[0114] Iodine absorbent is transported from absorbent mixing tank 10 to ejector 8 via circulating pump 9. Ejector 8 is connected to gaseous membrane element. The vacuum degree of the shell side of gaseous membrane element is controlled at -0.085MPa by adjusting vacuum control valve 7, so that iodine molecules enter ejector 8 under negative pressure and are fully mixed with absorbent. Sodium hydroxide is used as absorbent, the temperature of absorbent is controlled at 40℃, and the circulation rate of absorbent is controlled at 25, so that iodine is enriched in absorbent.

[0115] After oxidation by the six-stage oxidative extraction unit (6-stage pipeline mixer 3) and extraction by the six-stage gas membrane iodine extraction device (5), the iodine ion concentration in the iodine-extracting water is 275 mg / L, and the iodine ion recovery rate reaches 94.3%.

[0116] Example 7

[0117] This embodiment provides an extraction method for the gaseous membrane iodine extraction system of Example 3, including the following steps:

[0118] Iodine-containing wastewater is added to iodine-containing material storage tank 1, oxidant is added to pipeline mixer 3, and absorbent is added to absorbent mixing tank 10.

[0119] Turn on waste liquid transfer pump 2; turn on preheating tank 4, adjust the temperature of the heating tank to 40℃, and set the preheating residence time to 2h; turn on gaseous membrane iodine extraction device 5, and control the flow rate of the material in the tube side of the gaseous membrane element of gaseous membrane iodine extraction device 5 to 0.5m / s.

[0120] Turn on heat exchanger 6 and set the temperature to 22℃;

[0121] Adjust the vacuum control valve 7 to control the vacuum level of the gaseous membrane element shell to -0.085MPa; adjust the temperature of the absorbent in the absorbent mixing tank 10 to 40℃; adjust the circulation pump 9 to control the circulation rate of the absorbent to 25 times / hour.

[0122] The iodide ion concentration in the iodine-containing wastewater was 4845 mg / L, and the total dissolved salt content was 214 g / L. Chlorine was used as the oxidant, with a chlorine addition ratio of Cl2:I molar ratio of 0.8:1. Sodium hydroxide was used as the absorbent.

[0123] Among them, the pipeline mixer 3 adopts an 8-section pipeline mixer 3; the preheating tank 4 is filled with packing material made of PTFE; the gaseous membrane iodine extraction module adopts a 6-stage iodine oxidation extraction unit; the gaseous membrane element of the gaseous membrane iodine extraction device 5 is made of a modified membrane with PTFE substrate.

[0124] The extraction process for iodine-containing wastewater is as follows:

[0125] Iodine-containing wastewater is transported from iodine-containing material storage tank 1 to waste liquid transfer pump 2, and then fully mixed with oxidant in pipeline mixer 3. The mixed product water enters preheating tank 4 and stays in preheating tank 4 at 40°C for 2 hours. During this time, iodide ions are oxidized to elemental iodine. The elemental iodine is then heated in preheating tank 4 and transported to the tube side of gaseous membrane iodine extraction device 5, where it is converted into gaseous iodine molecules. These molecules then pass through the gaseous membrane and enter the shell side of the gaseous membrane element, thus achieving the separation of iodine molecules and wastewater.

[0126] This project adopts a 6-stage iodine oxidation extraction unit. The iodine-extracting water from the first-stage iodine oxidation extraction unit is cooled by heat exchanger 6. Heat exchanger 6 controls the water temperature to below 25°C. Then, it enters the next-stage pipeline mixer 3 for oxidation and the next-stage gaseous membrane iodine extraction device 5 for extraction. Finally, the iodine-extracting water is discharged.

[0127] Iodine absorbent is transported from absorbent mixing tank 10 to ejector 8 via circulating pump 9. Ejector 8 is connected to gaseous membrane element. The vacuum degree of the gaseous membrane shell side is controlled at -0.085MPa by adjusting vacuum control valve 7, so that iodine molecules enter ejector 8 under negative pressure and mix thoroughly with absorbent. Sodium hydroxide is used as absorbent, the temperature of absorbent is controlled at 40℃, and the circulation rate of absorbent is controlled at 25 times / hour, so as to achieve iodine enrichment in absorbent.

[0128] After oxidation by the six-stage oxidative extraction unit (6-stage pipeline mixer 3) and extraction by the six-stage gaseous membrane iodine extraction device (5), the iodine ion concentration in the iodine-extracting water is 375 mg / L, and the iodine ion recovery rate reaches 92.2%.

[0129] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0130] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0131] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gaseous membrane iodine extraction system, characterized in that, It includes a liquid delivery module, a gaseous membrane iodine extraction module, and an iodine enrichment module; The gaseous membrane iodine extraction module includes at least one stage of iodine oxidation extraction unit, which includes a pipeline mixer (3), a preheating tank (4), and a gaseous membrane iodine extraction device (5). The liquid delivery module is connected to the inlet of the pipeline mixer (3), the outlet of the pipeline mixer (3) is connected to the inlet of the preheating tank (4), the outlet of the preheating tank (4) is connected to the inlet of the gaseous membrane iodine extraction device (5), the iodine enrichment module is connected to the gaseous membrane element of the gaseous membrane iodine extraction device (5), and the outlet of the gaseous membrane iodine extraction module is used to discharge the iodine extraction water after iodine extraction.

2. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The gaseous membrane iodine extraction module includes 2 to 6 stages of iodine oxidation extraction units; The outlet of the first-stage gaseous membrane iodine extraction device (5) is connected to the inlet of the pipe mixer (3) of the adjacent second-stage iodine oxidation extraction unit. The outlet of the gaseous membrane iodine extraction device (5) of the last-stage iodine oxidation extraction unit is used to discharge the iodine-extracting water after iodine extraction.

3. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The gaseous membrane iodine extraction module also includes a heat exchanger (6), which is connected between the two stages of iodine oxidation extraction unit; The inlet of the heat exchanger (6) is connected to the outlet of the gaseous membrane iodine extraction device (5) of the previous stage iodine oxidation extraction unit and the cooled iodine-extracting water is transported to the inlet of the pipeline mixer (3) of the next stage gaseous membrane iodine extraction device (5).

4. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The iodine enrichment module includes an absorption liquid mixing tank (10), a circulation pump (9), an ejector (8), and a vacuum control valve (7). The circulation outlet of the absorption liquid mixing tank (10) is connected to the inlet of the circulation pump (9), the outlet of the circulation pump (9) is connected to the inlet of the ejector (8), the air inlet of the ejector (8) is connected to the gaseous membrane element of the gaseous membrane iodine extraction device (5) of the last extraction stage of the iodine oxidation extraction unit, and the outlet of the ejector (8) is connected to the circulation inlet of the absorption liquid circulation tank; the vacuum control valve (7) is connected to the gaseous membrane element of the gaseous membrane iodine extraction device (5) of the iodine oxidation extraction unit.

5. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The preheating tank (4) is provided with packing material, which includes one or a combination of polyvinylidene fluoride, polytetrafluoroethylene and polypropylene.

6. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The gaseous membrane material of the gaseous membrane iodine extraction device (5) includes one of polyvinylidene fluoride, polytetrafluoroethylene, and polypropylene.

7. The gaseous membrane iodine extraction system according to claim 1, characterized in that, The pipe mixer (3) is a pipe mixer (3) with 3 to 10 sections.

8. A method for gaseous membrane iodine extraction, based on the gaseous membrane iodine extraction system according to any one of claims 1-7, characterized in that, Includes the following steps: Iodine-containing wastewater is transported by the liquid delivery module to the pipeline mixer (3) for mixing to obtain mixed product water; The mixed permeate is transported to the preheating tank (4) and heated according to the preset heating conditions to obtain iodine-extracting permeate containing gasified iodine molecules; The iodine-extraction water containing vaporized iodine molecules is transported to the gas membrane iodine extraction device (5) and gas-liquid separation is carried out at the gas membrane interface according to the preset separation conditions to obtain vaporized iodine molecules; Vaporized iodine molecules are transported to an iodine enrichment module under vacuum conditions for enrichment, thus obtaining extracted iodine.

9. The gaseous membrane iodine extraction method according to claim 8, characterized in that, It also includes transporting the iodine-extracting water from the previous stage to a heat exchanger (6), cooling the iodine-extracting water according to preset heat exchange conditions, and then transporting the cooled iodine-extracting water to the pipeline reactor of the next stage for further oxidation of iodine ions.

10. The gaseous membrane iodine extraction method according to claim 8, characterized in that, The vacuum condition is as follows: the vacuum degree of the shell side of the gaseous membrane element of the gaseous membrane iodine extraction device is controlled at 0.01~0.1MPa.

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