Device for recovering heavy metal mercury ions in petrochemical sewage through multiple coupling

Abstract

The invention particularly relates to a device for recycling heavy metal mercury ions in petrochemical sewage through multiple coupling, and belongs to the technical field of heavy metal wastewater treatment. According to the device, through multi-stage cooperation of the pretreatment unit, the electrochemical reaction tank, the membrane separation unit, the mercury recovery unit and the tail gas treatment unit, the graphene / carbon nano tube composite electrode is adopted to reinforce electrochemical reduction of mercury ions, and the nanofiltration-reverse osmosis membrane concentration and vacuum distillation technologies are combined, so that efficient enrichment and recovery of mercury are realized. Wherein the three-dimensional electrode structure improves the adsorption capacity and the reaction rate, mercury separation is achieved at low temperature through vacuum distillation, tail gas is subjected to dual treatment of activated carbon adsorption and alkaline washing, and it is ensured that the mercury recovery rate is larger than 98% and emission reaches the standard. The device solves the problems of secondary pollution and high energy consumption of sludge in a traditional method, and is suitable for mercury-containing sewage treatment and recycling in industries such as petrochemical industry and chemical industry.

Description

Technical Field

[0001] The invention belongs to the technical field of heavy metal wastewater treatment, and particularly relates to a device for recovering heavy metal mercury ions in petrochemical wastewater through multiple coupling. Background Art

[0002] Existing mercury-containing wastewater treatment technologies (such as chemical precipitation, adsorption, membrane separation, and electrochemical methods) generally suffer from low efficiency, severe secondary pollution, and high operating costs. For example, chemical precipitation produces mercury-containing sludge, requiring additional solid waste treatment; adsorption methods are prone to material saturation and have high regeneration costs; single membrane separation technologies are prone to pollution and consume a lot of energy; and traditional electrochemical methods are limited by small electrode surface area, numerous side reactions, and short lifespans, resulting in low mercury recovery efficiency and insufficient purity. Furthermore, existing processes struggle to achieve efficient concentration, resource recovery, and compliance with tail gas emission standards, resulting in poor system stability. Some researchers have begun researching mercury recovery. US5200087A discloses a mercury recovery device, but its structure still requires optimization. Therefore, there is an urgent need to develop a coupled device that integrates electrochemical reduction, graded membrane separation, and vacuum distillation. By using three-dimensional nanocomposite electrodes to enhance adsorption and reaction efficiency, combined with membrane separation-distillation gradient concentration and purification, and incorporating activated carbon-alkaline tail gas scrubbing, this device can achieve efficient mercury recovery, reduced energy consumption, and near-zero emissions. Summary of the Invention

[0003] The present invention aims to address the shortcomings of existing mercury-containing wastewater treatment technologies, such as low recovery efficiency, serious secondary pollution, and high operating energy consumption. Through a multi-coupled process of electrochemical reduction-graded membrane separation-vacuum distillation, the invention achieves efficient enrichment of mercury ions, high-purity recovery, and near-zero tail gas emissions, while reducing energy consumption and operating costs and improving system stability.

[0004] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater includes a pretreatment unit, an electrochemical reaction tank, a membrane separation unit, a mercury recovery unit, and an exhaust gas treatment unit connected in sequence. The pretreatment unit has a pipeline filter and a pH adjustment tank. The electrochemical reaction tank uses a graphene / carbon nanotube composite electrode. The membrane separation unit includes a nanofiltration membrane and a reverse osmosis membrane. The mercury recovery unit includes a vacuum distillation device and a condenser. The condenser is connected to a mercury collector. The exhaust gas treatment unit includes an activated carbon adsorption tower and an alkaline washing tower. The sewage enters the filter of the pretreatment unit, which is used to remove suspended matter and impurities in the sewage. The sewage then enters the pH adjustment tank, which adjusts the pH of the sewage to neutral or weakly alkaline to avoid interfering with subsequent electrochemical reactions. The electrochemical reaction tank uses a graphene / carbon nanotube composite electrode, which forms a three-dimensional network through a nano-scale porous structure, significantly increasing the effective surface area of ​​the electrode, providing more active sites, and enhancing the recovery of mercury ions (Hg 2+) on the electrode surface, improving the enrichment efficiency of the electrochemical reaction. Graphene and carbon nanotubes both have excellent electrical conductivity. After compounding, they form a continuous conductive network, which can reduce the internal resistance of the electrode, accelerate electron transfer, and increase the kinetic rate of the mercury ion reduction reaction (reaction formula: Hg 2+ +2e - =Hg).

[0005] Graphene / carbon nanotube materials exhibit excellent corrosion resistance in both acidic and alkaline environments, adapting to pH-adjusted wastewater environments (pH 6.5-8.0) and extending the life of the electrodes. The electrochemical reaction cell directly converts mercury ions into metallic mercury through electrochemical reduction, avoiding the production of mercury-containing sludge by traditional chemical precipitation methods. The mercury can then be collected on the electrodes. Nanofiltration membranes separate the concentrated mercury solution from other ions after the electrochemical reaction, and reverse osmosis membranes further concentrate the mercury solution, reducing subsequent processing requirements. The vacuum distillation unit significantly lowers the boiling point of mercury from 356.7°C at atmospheric pressure to 200-300°C, significantly reducing heat energy consumption. By utilizing the boiling point difference between mercury and other impurities, mercury is preferentially vaporized during the vacuum distillation process, achieving high-purity mercury separation. Under vacuum conditions, mercury is protected from oxygen, preventing oxidation of the mercury vapor and the formation of harmful compounds. The condenser, cooled by circulating water, rapidly condenses the gaseous mercury into liquid form.

[0006] The activated carbon adsorption tower utilizes the high specific surface area of ​​activated carbon to absorb trace amounts of uncondensed mercury vapor in the exhaust gas. The alkaline scrubber uses an alkaline solution (pH ≥ 11) to chemically react with mercury vapor, generating non-volatile mercury compounds that further absorb residual mercury vapor to ensure emissions meet standards.

[0007] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater uses a microporous filter with a filtration accuracy of at least 1 micron. A pH adjustment tank is equipped with a feeder and pH sensor, and an agitator operating at a stirring speed between 30 and 60 rpm. The filtration accuracy of at least 1 micron is intended to intercept fine suspended matter (such as colloidal particles) to prevent clogging of the electrodes in the subsequent electrochemical reaction cell. This device targets wastewater sources (such as chemical and smelting wastewater), which often contain acidic components (such as sulfuric acid and hydrochloric acid), resulting in a low (acidic) pH value in the raw water. The feeder has separate sodium hydroxide and sodium carbonate feed tanks. Sodium hydroxide is strongly alkaline and has a fast adjustment speed, making it suitable for highly acidic wastewater, but the dosage must be controlled to avoid localized over-alkalinity. Sodium carbonate is weakly alkaline and has a strong buffering capacity, making it suitable for less acidic wastewater. The pH sensor detects the pH change in the sewage, and then determines whether to add sodium hydroxide or sodium carbonate to adjust the pH value in the pH adjustment tank. The alkaline regulator increases the pH of the sewage from acidic to neutral or weakly alkaline (pH 6.5-8.0) to meet the optimal conditions for the subsequent electrochemical reaction.2+ Reduction to Hg is more efficient in neutral or slightly alkaline environments, avoiding the interference of the hydrogen evolution reaction under acidic conditions with mercury reduction. The agitator is used to thoroughly mix the dosing agent and wastewater to avoid local pH deviations.

[0008] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater features an electrochemical reaction cell operating voltage between 1.5 and 3 volts, a current density between 0.5 and 2 amperes per square decimeter, and an electrolyte flow rate between 0.5 and 2 meters per second. The cell is made of polypropylene, fiberglass, or titanium alloy, and the electrode spacing is between 1 and 5 centimeters. The lower voltage limit is 1.5 volts to ensure sufficient mercury ion reduction potential (standard reduction potential of mercury ion 0.85 V vs. SHE), while the upper voltage limit is 3 volts to suppress the chlorine evolution side reaction. A current density of 0.5 to 2 amperes per square decimeter is used to balance reaction speed and energy consumption, avoiding electrode passivation caused by excessive current. A smaller electrode spacing can easily lead to short circuits, while a larger spacing increases resistance. A suitable spacing is between 1 and 5 centimeters. Polypropylene exhibits excellent corrosion resistance to acids, bases, salt solutions, and most organic solvents, making it suitable for neutral to slightly alkaline environments. FRP is a composite of a resin matrix (such as epoxy resin) and glass fibers. It is resistant to strong acids, bases, and oxidizing media, making it suitable for complex chemical environments. Titanium alloy remains stable in strong acids and bases, making it particularly suitable for highly corrosive environments.

[0009] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater, wherein the nanofiltration membrane has a pore size of less than 1 nanometer, an operating pressure of 1 to 5 bar, a flow rate of 0.1 to 1 cubic meter / hour, and a reverse osmosis membrane (32) has a pore size of less than 0.1 nanometer, an operating pressure of 5 to 15 bar, and a flow rate of 0.1 to 0.5 cubic meter / hour. The nanofiltration membrane has a pore size of less than 1 nanometer and selectively intercepts mercury ions (the diameter of mercury ions is about 0.2 nanometers), allowing Na + / Cl - Small ions permeate, reducing membrane fouling. The nanofiltration membrane 31 operates within a pressure range of 1 to 5 bar, balancing retention (for divalent ions) with energy consumption and preventing membrane compaction. A flow rate of 0.1 to 1 cubic meter per hour suppresses concentration polarization while controlling shear stress. Building on the initial separation process of the nanofiltration membrane, the reverse osmosis membrane further removes water and low-molecular impurities, concentrating the mercury solution to a higher concentration. Driven by high pressure, the membrane passes through a dense separation layer (made of polyamide) with a pore size of 0.1 nanometer, retaining mercury ions and large molecular impurities while allowing only water molecules and a small number of monovalent ions to pass. The reverse osmosis membrane pressure range of 5 to 15 bar allows wastewater to break through the osmotic pressure without damaging the membrane. A flow rate of 0.1 to 1 cubic meter per hour matches the efficiency of high-pressure pumps and reduces the risk of membrane fouling. While the nanofiltration membrane carries 80% of the pollutant load, the reverse osmosis membrane's high-precision treatment only requires 20% of the water volume, significantly reducing overall system energy consumption.

[0010] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The vacuum distillation unit operates at a vacuum level between 0.1 and 1 Torr, a heating temperature between 200 and 300°C, and a distillation time between 1 and 2 hours. The condenser utilizes a serpentine tube structure, and the cooling medium is circulating water or oil. The vacuum distillation unit operates at a vacuum level between 0.1 and 1 Torr, lowering the boiling point of mercury from 356.6°C at atmospheric pressure to between 200 and 250°C, reducing energy consumption by over 30%. The heating temperature between 200 and 300°C ensures complete evaporation of mercury under vacuum conditions while preventing equipment corrosion caused by high temperatures.

[0011] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The activated carbon adsorption tower is filled with coconut shell activated carbon. The washing liquid in the alkaline washing tower has a pH of ≥10 and a spray density of 20 to 40 liters / (square meter·hour). The coconut shell activated carbon has an adsorption efficiency of up to 99% for mercury vapor. The alkaline washing liquid with a pH of ≥10 can promote the removal of Hg 0 Oxidized to Hg 2+ And with OH - Form Hg(OH)2 precipitation to ensure that the exhaust gas meets the standards.

[0012] A multi-coupling device for recovering heavy metal mercury ions in petrochemical wastewater comprises a first pipe connecting a filter and a pH regulating tank, a second pipe connecting the pH regulating tank and an electrochemical reaction tank, a third pipe connecting the electrochemical reaction tank and a membrane separation unit, an eleventh pipe being provided on the electrochemical reaction tank, a fourth pipe connecting the membrane separation unit and a mercury recovery unit, a fifth pipe connecting the vacuum distillation device and a condenser, a sixth pipe connecting the condenser and a mercury collector, a seventh pipe connecting the condenser and an activated carbon adsorption tower, and an eighth pipe connecting the activated carbon adsorption tower and an alkaline washing tower.

[0013] A multi-coupling device for recovering heavy metal mercury ions in petrochemical wastewater comprises: a first pipeline provided with a first pump, a second pipeline provided with a second pump and a first valve, a third pipeline provided with a third pump and a second valve, a fourth pipeline provided with a fourth pump, a fifth pipeline provided with a third valve, a sixth pipeline provided with a fourth valve, a seventh pipeline provided with a fifth valve and the fifth pump, and an eleventh pipeline provided with a seventh valve.

[0014] A multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater includes a tail gas treatment unit, including a spare activated carbon adsorption tower. A ninth pipeline connects the spare activated carbon adsorption tower and the alkaline scrubber. A tenth pipeline connects the spare activated carbon adsorption tower and the alkaline scrubber. A mercury vapor analyzer is located in the eighth pipeline, and a sixth valve and pump are located in the ninth pipeline. The device includes an automatic control system that controls the opening and closing of pumps 1, 2, 3, 4, 5, and 6, as well as the first, second, third, fourth, fifth, and sixth valves. The automatic control system is electrically connected to a filter, a pH adjustment tank, an electrochemical reaction tank, a nanofiltration membrane, a reverse osmosis membrane, a vacuum distillation apparatus, a condenser, an activated carbon adsorption tower, an alkaline scrubber, and the spare activated carbon adsorption tower to collect real-time data on various process parameters (such as pH, voltage, and flow rate). The automatic control system monitors and optimizes process parameters in real time to improve recovery efficiency and stability. It can automatically adjust parameters such as voltage, current, flow rate, etc. according to process requirements, set parameter over-limit alarms, and handle abnormal situations in a timely manner.

[0015] The present invention enhances the electrochemical reduction efficiency through graphene / carbon nanotube composite electrodes, combines nanofiltration-reverse osmosis membrane graded concentration with vacuum distillation and low-temperature purification technology, and achieves efficient resource recovery with a mercury ion recovery rate of ≥98%; at the same time, it adopts activated carbon-alkaline washing tail gas purification and intelligent control system, and solves the pain points of serious secondary pollution and unstable operation of traditional processes on the basis of reducing comprehensive energy consumption, forming a low-energy consumption, near-zero emission closed-loop system for mercury-containing wastewater treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0017] Figure 1 This is a schematic diagram of the overall device of Example 1 of the present invention.

[0018] Figure 2 This is a schematic diagram of the overall device of Example 2 of the present invention.

[0019] Figure 3 Schematic diagram of the pretreatment unit and electrochemical reaction tank of the present invention.

[0020] Figure 4 This is a schematic diagram of the mercury recovery unit and tail gas treatment unit in Example 1 of the present invention.

[0021] Figure 5 This is a schematic diagram of the tail gas treatment unit of Example 2 of the present invention.

[0022] Description of the drawings: 1-pretreatment unit, 2-electrochemical reaction tank, 3-membrane separation unit, 4-mercury recovery unit, 5-tail gas treatment unit, 11-filter, 12-pH adjustment tank, 31-nanofiltration membrane, 32-reverse osmosis membrane, 41-vacuum distillation device, 42-condenser, 43-mercury collector, 51-activated carbon adsorption tower, 52-alkaline washing tower, 53-mercury vapor analyzer, 54-spare activated carbon adsorption tower, 61-pump No. 1, 62-pump No. 2, 63-pump No. 3, 64-pump No. 4, 65-pump No. 5, 66-pump No. 6 Pump, 71-first pipeline, 72-second pipeline, 73-third pipeline, 74-fourth pipeline, 75-fifth pipeline, 76-sixth pipeline, 77-seventh pipeline, 78-eighth pipeline, 79-ninth pipeline, 710-tenth pipeline, 711-eleventh pipeline, 81-first valve, 82-second valve, 83-third valve, 84-fourth valve, 85-fifth valve, 86-sixth valve, 87-seventh valve, 9-automatic control system, 121-feeder, 122-pH sensor, 123-agitator. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0024] Example 1: Refer to the attached Figure 1 , Attachment Figure 3As shown, a multi-coupled device for recovering heavy metal mercury ions from petrochemical wastewater comprises a pretreatment unit 1, an electrochemical reaction tank 2, a membrane separation unit 3, a mercury recovery unit 4, and an exhaust gas treatment unit 5, which are connected in sequence. Pretreatment unit 1 includes a pipeline filter 11 and a pH adjustment tank 12. The electrochemical reaction tank 2 uses a graphene / carbon nanotube composite electrode. The membrane separation unit 3 includes a nanofiltration membrane 31 and a reverse osmosis membrane 32. The mercury recovery unit 4 includes a vacuum distillation apparatus 41 and a condenser 42, which is connected to a mercury collector 43. The exhaust gas treatment unit 5 includes an activated carbon adsorption tower 51 and an alkaline scrubber 52. The wastewater enters filter 11 of pretreatment unit 1, which removes suspended matter and impurities. The wastewater then enters pH adjustment tank 12, which adjusts the pH of the wastewater to neutral or weakly alkaline to avoid interference with subsequent electrochemical reactions. The electrochemical reaction tank 2 uses a graphene / carbon nanotube composite electrode, which forms a three-dimensional network through a nano-scale porous structure, significantly increasing the effective surface area of ​​the electrode, providing more active sites, and enhancing the mercury ion (Hg 2+ ) on the electrode surface, improving the enrichment efficiency of the electrochemical reaction. Graphene and carbon nanotubes both have excellent electrical conductivity. After compounding, they form a continuous conductive network, which can reduce the internal resistance of the electrode, accelerate electron transfer, and increase the kinetic rate of the mercury ion reduction reaction (reaction formula: Hg 2+ +2e - =Hg).

[0025] Graphene / carbon nanotube materials exhibit excellent corrosion resistance in both acidic and alkaline environments and are adaptable to pH-adjusted wastewater environments (pH 6.5-8.0), extending the life of the electrodes. Electrochemical reaction cell 2 directly converts mercury ions into metallic mercury through electrochemical reduction, avoiding the generation of mercury-containing sludge by traditional chemical precipitation methods. Mercury can then be collected on the electrodes. Nanofiltration membrane 31 separates the mercury solution enriched after the electrochemical reaction from other ions, and reverse osmosis membrane 32 further concentrates the mercury solution, reducing subsequent processing requirements. Vacuum distillation unit 41 significantly lowers the boiling point of mercury from 356.7°C at atmospheric pressure to 200-300°C, significantly reducing heat energy consumption. By utilizing the boiling point difference between mercury and other impurities, mercury is preferentially vaporized during the vacuum distillation process, achieving high-purity mercury separation. Under vacuum conditions, mercury is prevented from coming into contact with oxygen, preventing oxidation of mercury vapor and the formation of harmful compounds. Condenser 42, cooled by circulating water, rapidly condenses gaseous mercury into liquid form.

[0026] Activated carbon adsorption tower 51 utilizes the high specific surface area of ​​activated carbon to absorb trace amounts of uncondensed mercury vapor in the exhaust gas. Alkaline scrubber 52 uses an alkaline solution (pH ≥ 11) to chemically react with mercury vapor, generating non-volatile mercury compounds that further absorb residual mercury vapor, ensuring emissions meet standards.

[0027] Refer to the attached Figure 1 , Attachment Figure 3 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The filter 11 is a microporous filter with a filtration accuracy of at least 1 micron. A pH adjustment tank 12 is equipped with a feeder 121 and a pH sensor 122. The pH adjustment tank 12 also includes an agitator 123 with a stirring speed between 30 and 60 rpm. The filtration accuracy of at least 1 micron is intended to intercept fine suspended matter (such as colloidal particles) to prevent clogging of the electrode pores in the subsequent electrochemical reaction cell 2. This device targets wastewater sources (such as chemical and smelting wastewater), which typically contain acidic components (such as sulfuric acid and hydrochloric acid), resulting in a low (acidic) pH value in the raw water. The feeder 121 has separate sodium hydroxide and sodium carbonate feed tanks. Sodium hydroxide is strongly alkaline and has a fast pH adjustment rate, making it suitable for highly acidic wastewater, but the dosage must be controlled to avoid localized over-alkalinity. Sodium carbonate is weakly alkaline and has a strong buffering capacity, making it suitable for less acidic wastewater. The pH sensor 122 detects the pH change in the sewage, and thus determines whether to add sodium hydroxide or sodium carbonate to adjust the pH value in the pH adjustment tank 12. The alkaline regulator increases the pH of the sewage from acidic to neutral or weakly alkaline (between pH 6.5 and 8.0) to meet the optimal conditions for the subsequent electrochemical reaction. 2+ Reduction to Hg is more efficient in neutral or weakly alkaline environments, avoiding interference of the hydrogen evolution reaction with mercury reduction under acidic conditions. Agitator 123 is used to thoroughly mix the dosing agent and wastewater to avoid local pH deviations.

[0028] Refer to the attached Figure 1 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The electrochemical reaction cell 2 operates at a voltage between 1.5 and 3 volts, a current density between 0.5 and 2 amperes per square decimeter, and an electrolyte flow rate between 0.5 and 2 meters per second. The electrochemical reaction cell 2 is made of polypropylene, fiberglass, or titanium alloy, and the electrode spacing is between 1 and 5 centimeters. The lower voltage limit is 1.5 volts to ensure sufficient drive at the mercury ion reduction potential (standard reduction potential of mercury ion 0.85 V vs. SHE), while the upper voltage limit is 3 volts to suppress the chlorine evolution side reaction. The current density is between 0.5 and 2 amperes per square decimeter to balance reaction speed and energy consumption, avoiding electrode passivation caused by excessive current. Too small an electrode spacing can easily lead to short circuits, while too large a spacing increases resistance. A suitable spacing is between 1 and 5 centimeters. Polypropylene has excellent corrosion resistance to acids, bases, salt solutions, and most organic solvents, making it suitable for neutral to slightly alkaline environments. FRP is a composite of a resin matrix (such as epoxy resin) and glass fibers. It is resistant to strong acids, bases, and oxidizing media, making it suitable for complex chemical environments. Titanium alloy remains stable in strong acids and bases, making it particularly suitable for highly corrosive environments.

[0029] Refer to the attached Figure 1As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater has a nanofiltration membrane 31 with a pore size of less than 1 nanometer, an operating pressure of 1 to 5 bar, and a flow rate of 0.1 to 1 cubic meter per hour. The reverse osmosis membrane 32 has a pore size of less than 0.1 nanometer, an operating pressure of 5 to 15 bar, and a flow rate of 0.1 to 0.5 cubic meter per hour. The nanofiltration membrane 31 has a pore size of less than 1 nanometer and selectively intercepts mercury ions (mercury ions have a diameter of about 0.2 nanometers), allowing Na, a common substance in industrial wastewater, to be removed. + / Cl - The nanofiltration membrane 31 operates within a pressure range of 1 to 5 bar, balancing retention (for divalent ions) with energy consumption and preventing membrane compaction. A flow rate of 0.1 to 1 cubic meter per hour suppresses concentration polarization while controlling shear stress. Building on the initial separation process of the nanofiltration membrane 31, the reverse osmosis membrane 32 further removes water and low-molecular impurities, concentrating the mercury solution to a higher concentration. Driven by high pressure, the membrane passes through a dense separation layer (made of polyamide) with a pore size of 0.1 nanometer, retaining mercury ions and large molecular impurities while allowing only water molecules and a small number of monovalent ions to pass. The reverse osmosis membrane 32 operates within a pressure range of 5 to 15 bar, allowing wastewater to break through the osmotic pressure without damaging the membrane. A flow rate of 0.1 to 1 cubic meter per hour matches the efficiency of high-pressure pumps and reduces the risk of membrane fouling. The nanofiltration membrane 31 carries 80% of the pollutant load, while the reverse osmosis membrane 32 only needs to treat 20% of the water volume for high-precision treatment, significantly reducing overall system energy consumption.

[0030] Refer to the attached Figure 3 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The vacuum distillation unit 41 maintains a vacuum level between 0.1 and 1 Torr, a heating temperature between 200 and 300°C, and a distillation time between 1 and 2 hours. The condenser 42 utilizes a serpentine tube structure, and the cooling medium is circulating water or oil. The vacuum level of the vacuum distillation unit 41 is between 0.1 and 1 Torr, lowering the boiling point of mercury from 356.6°C at atmospheric pressure to between 200 and 250°C, reducing energy consumption by over 30%. The heating temperature between 200 and 300°C ensures complete evaporation of mercury under vacuum conditions while preventing equipment corrosion caused by high temperatures.

[0031] Refer to the attached Figure 3 As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater is shown. The activated carbon adsorption tower 51 is filled with coconut shell activated carbon, and the washing liquid in the alkaline washing tower 52 has a pH value of ≥10 and a spray density of 20 to 40 liters / (m2·hour). The coconut shell activated carbon has an adsorption efficiency of up to 99% for mercury vapor. The alkaline washing liquid with a pH value of ≥10 can promote the removal of Hg 0 Oxidized to Hg 2+ And with OH - Form Hg(OH)2 precipitation to ensure that the exhaust gas meets the standards.

[0032] Refer to the attached Figure 1 , Attachment Figure 3 , Attachment Figure 4 As shown, a multi-coupling device for recovering heavy metal mercury ions in petrochemical wastewater, wherein a first pipe 71 is connected between the filter 11 and the pH regulating tank 12, a second pipe 72 is connected between the pH regulating tank 12 and the electrochemical reaction tank 2, a third pipe 73 is connected between the electrochemical reaction tank 2 and the membrane separation unit 3, an eleventh pipe 711 is provided on the electrochemical reaction tank 2, a fourth pipe 74 is connected between the membrane separation unit 3 and the mercury recovery unit 4, a fifth pipe 75 is connected between the vacuum distillation device 41 and the condenser 42, a sixth pipe 76 is connected between the condenser 42 and the mercury collector 43, a seventh pipe 77 is connected between the condenser 42 and the activated carbon adsorption tower 51, and an eighth pipe 78 is connected between the activated carbon adsorption tower 51 and the alkaline washing tower 52.

[0033] Refer to the attached Figure 1 , Attachment Figure 3 , Attachment Figure 4 , Attachment Figure 5 As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater includes an automatic control system 9. This system controls the opening and closing of pumps 1, 61, 62, 63, 64, 65, 66, and valves 81, 82, 83, 84, 85, and 86. The automatic control system 9 is electrically connected to a filter 11, a pH adjustment tank 12, an electrochemical reaction tank 2, a nanofiltration membrane 31, a reverse osmosis membrane 32, a vacuum distillation apparatus 41, a condenser 42, an activated carbon adsorption tower 51, an alkaline scrubber 52, and a backup activated carbon adsorption tower 54. The automatic control system 9 is used to collect real-time data on various process parameters (such as pH, voltage, and flow rate). The automatic control system 9 monitors and optimizes process parameters in real time to improve recovery efficiency and stability. It can automatically adjust parameters such as voltage, current, and flow rate based on process requirements, and can set alarms for parameter over-limits to promptly address abnormal situations.

[0034] Refer to the attached Figure 1 , Attachment Figure 3As shown, a multi-coupled device for recovering heavy metal mercury ions from petrochemical wastewater includes a first pump 61 in a first pipe 71, a second pump 62 and a first valve 81 in a second pipe 72, a third pump 63 and a second valve 82 in a third pipe 73, a fourth pump 64 in a fourth pipe 74, a third valve 83 in a fifth pipe, a fourth valve 84 in a sixth pipe, a fifth valve 85 and a fifth pump 65 in a seventh pipe 77, and a seventh valve 87 in an eleventh pipe 711. Petrochemical wastewater flowing out of the factory first enters a filter 11 for filtration. As it flows through the first pipe 71, pump 61 regulates the rate at which the wastewater enters the pH adjustment tank 12 to prevent excessive pH fluctuations in the pH adjustment tank 12. When the pH in pH adjustment tank 12 reaches the set value (pH 6.5-8.0), the first valve 81 and second pump 62 are opened, and wastewater is drawn into electrochemical reaction tank 2 by second pump 62. The anode of electrochemical reaction tank 2 produces oxygen and chlorine when treating the wastewater. When these gases reach a certain level, seventh valve 87 is opened and they flow out through eleventh pipe 711 for treatment. A large amount of mercury is produced at the cathode of electrochemical reaction tank 2. This mercury can be collected by replacing the electrodes and cleaning the motor. After a period of time, third pump 63 and second valve 82 are opened, and the remaining wastewater flows through third pipe 73 into membrane separation unit 3. Membrane separation unit 3 is used to further concentrate and separate the enriched mercury solution, improving recovery efficiency. The mercury-containing liquid retained by membrane separation unit 3 is then pumped by fourth pump 64 and enters vacuum distillation unit 41 through fourth pipe 74. The vacuum distillation device 41 performs vacuum distillation on the concentrated mercury solution to separate high-purity mercury. The third valve 83 is opened to allow the mercury vapor to enter the condenser 42. After a period of time, the fourth valve 84 is opened, and the high-purity liquid mercury condensed in the condenser 42 enters the mercury collector 43 through the sixth pipe 76. After the collection is completed, the fourth valve 84 is closed. The fifth valve 85 and the fifth pump 65 are opened, and the remaining exhaust gas flows through the seventh and eighth pipes into the activated carbon adsorption tower (51) and the alkaline washing tower 52 for treatment to ensure that the emission meets the standards.

[0035] Example 2: Refer to the attached Figure 2 , Attachment Figure 3As shown, a multi-coupled device for recovering heavy metal mercury ions from petrochemical wastewater comprises a pretreatment unit 1, an electrochemical reaction tank 2, a membrane separation unit 3, a mercury recovery unit 4, and an exhaust gas treatment unit 5, which are connected in sequence. Pretreatment unit 1 includes a pipeline filter 11 and a pH adjustment tank 12. The electrochemical reaction tank 2 uses a graphene / carbon nanotube composite electrode. The membrane separation unit 3 includes a nanofiltration membrane 31 and a reverse osmosis membrane 32. The mercury recovery unit 4 includes a vacuum distillation apparatus 41 and a condenser 42, which is connected to a mercury collector 43. The exhaust gas treatment unit 5 includes an activated carbon adsorption tower 51 and an alkaline scrubber 52. The wastewater enters filter 11 of pretreatment unit 1, which removes suspended matter and impurities. The wastewater then enters pH adjustment tank 12, which adjusts the pH of the wastewater to neutral or weakly alkaline to avoid interference with subsequent electrochemical reactions. The electrochemical reaction tank 2 uses a graphene / carbon nanotube composite electrode, which forms a three-dimensional network through a nano-scale porous structure, significantly increasing the effective surface area of ​​the electrode, providing more active sites, and enhancing the mercury ion (Hg 2+ ) on the electrode surface, improving the enrichment efficiency of the electrochemical reaction. Graphene and carbon nanotubes both have excellent electrical conductivity. After compounding, they form a continuous conductive network, which can reduce the internal resistance of the electrode, accelerate electron transfer, and increase the kinetic rate of the mercury ion reduction reaction (reaction formula: Hg 2+ +2e - =Hg).

[0036] Graphene / carbon nanotube materials exhibit excellent corrosion resistance in both acidic and alkaline environments and are adaptable to pH-adjusted wastewater environments (pH 6.5-8.0), extending the life of the electrodes. Electrochemical reaction cell 2 directly converts mercury ions into metallic mercury through electrochemical reduction, avoiding the generation of mercury-containing sludge by traditional chemical precipitation methods. Mercury can then be collected on the electrodes. Nanofiltration membrane 31 separates the mercury solution enriched after the electrochemical reaction from other ions, and reverse osmosis membrane 32 further concentrates the mercury solution, reducing subsequent processing requirements. Vacuum distillation unit 41 significantly lowers the boiling point of mercury from 356.7°C at atmospheric pressure to 200-300°C, significantly reducing heat energy consumption. By utilizing the boiling point difference between mercury and other impurities, mercury is preferentially vaporized during the vacuum distillation process, achieving high-purity mercury separation. Under vacuum conditions, mercury is prevented from coming into contact with oxygen, preventing oxidation of mercury vapor and the formation of harmful compounds. Condenser 42, cooled by circulating water, rapidly condenses gaseous mercury into liquid form.

[0037] Activated carbon adsorption tower 51 utilizes the high specific surface area of ​​activated carbon to absorb trace amounts of uncondensed mercury vapor in the exhaust gas. Alkaline scrubber 52 uses an alkaline solution (pH ≥ 11) to chemically react with mercury vapor, generating non-volatile mercury compounds that further absorb residual mercury vapor, ensuring emissions meet standards.

[0038] Refer to the attached Figure 2 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The filter 11 is a microporous filter with a filtration accuracy of at least 1 micron. A pH adjustment tank 12 is equipped with a feeder 121 and a pH sensor 122. The pH adjustment tank 12 also includes an agitator 123 with a stirring speed between 30 and 60 rpm. The filtration accuracy of at least 1 micron is intended to intercept fine suspended matter (such as colloidal particles) to prevent clogging of the electrode pores in the subsequent electrochemical reaction cell 2. This device targets wastewater sources (such as chemical and smelting wastewater), which typically contain acidic components (such as sulfuric acid and hydrochloric acid), resulting in a low (acidic) pH value in the raw water. The feeder 121 has separate sodium hydroxide and sodium carbonate feed tanks. Sodium hydroxide is strongly alkaline and has a fast pH adjustment rate, making it suitable for highly acidic wastewater, but the dosage must be controlled to avoid localized over-alkalinity. Sodium carbonate is weakly alkaline and has a strong buffering capacity, making it suitable for less acidic wastewater. The pH sensor 122 detects the pH change in the sewage, and determines whether to add sodium hydroxide or sodium carbonate to adjust the pH value in the pH adjustment tank 12. The alkaline regulator increases the pH of the sewage from acidic to neutral or weakly alkaline (pH 6.5-8.0) to meet the optimal conditions for the subsequent electrochemical reaction. 2+ Reduction to Hg is more efficient in neutral or weakly alkaline environments, avoiding interference of the hydrogen evolution reaction with mercury reduction under acidic conditions. Agitator 123 is used to thoroughly mix the dosing agent and wastewater to avoid local pH deviations.

[0039] Refer to the attached Figure 2 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The electrochemical reaction cell 2 operates at a voltage between 1.5 and 3 volts, a current density between 0.5 and 2 amperes per square decimeter, and an electrolyte flow rate between 0.5 and 2 meters per second. The electrochemical reaction cell 2 is made of polypropylene, fiberglass, or titanium alloy, and the electrode spacing is between 1 and 5 centimeters. The lower voltage limit is 1.5 volts to ensure sufficient drive at the mercury ion reduction potential (standard reduction potential of mercury ion 0.85 V vs. SHE), while the upper voltage limit is 3 volts to suppress the chlorine evolution side reaction. The current density is between 0.5 and 2 amperes per square decimeter to balance reaction speed and energy consumption, avoiding electrode passivation caused by excessive current. Too small an electrode spacing can easily lead to short circuits, while too large a spacing increases resistance. A suitable spacing is between 1 and 5 centimeters. Polypropylene has excellent corrosion resistance to acids, bases, salt solutions, and most organic solvents, making it suitable for neutral to slightly alkaline environments. FRP is a composite of a resin matrix (such as epoxy resin) and glass fibers. It is resistant to strong acids, bases, and oxidizing media, making it suitable for complex chemical environments. Titanium alloy remains stable in strong acids and bases, making it particularly suitable for highly corrosive environments.

[0040] Refer to the attached Figure 2As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater has a nanofiltration membrane 31 with a pore size of less than 1 nanometer, an operating pressure of 1 to 5 bar, and a flow rate of 0.1 to 1 cubic meter per hour. The reverse osmosis membrane 32 has a pore size of less than 0.1 nanometer, an operating pressure of 5 to 15 bar, and a flow rate of 0.1 to 0.5 cubic meter per hour. The nanofiltration membrane 31 has a pore size of less than 1 nanometer and selectively intercepts mercury ions (mercury ions have a diameter of about 0.2 nanometers), allowing Na, a common substance in industrial wastewater, to be removed. + / Cl - The nanofiltration membrane 31 operates within a pressure range of 1 to 5 bar, balancing retention (for divalent ions) with energy consumption and preventing membrane compaction. A flow rate of 0.1 to 1 cubic meter per hour suppresses concentration polarization while controlling shear stress. Building on the initial separation process of the nanofiltration membrane 31, the reverse osmosis membrane 32 further removes water and low-molecular impurities, concentrating the mercury solution to a higher concentration. Driven by high pressure, the membrane passes through a dense separation layer (made of polyamide) with a pore size of 0.1 nanometer, retaining mercury ions and large molecular impurities while allowing only water molecules and a small number of monovalent ions to pass. The reverse osmosis membrane 32 operates within a pressure range of 5 to 15 bar, allowing wastewater to break through the osmotic pressure without damaging the membrane. A flow rate of 0.1 to 1 cubic meter per hour matches the efficiency of high-pressure pumps and reduces the risk of membrane fouling. The nanofiltration membrane 31 carries 80% of the pollutant load, while the reverse osmosis membrane 32 only needs to treat 20% of the water volume for high-precision treatment, significantly reducing overall system energy consumption.

[0041] Refer to the attached Figure 3 The figure shows a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater. The vacuum distillation unit 41 maintains a vacuum level between 0.1 and 1 Torr, a heating temperature between 200 and 300°C, and a distillation time between 1 and 2 hours. The condenser 42 utilizes a serpentine tube structure, and the cooling medium is circulating water or oil. The vacuum level of the vacuum distillation unit 41 is between 0.1 and 1 Torr, lowering the boiling point of mercury from 356.6°C at atmospheric pressure to between 200 and 250°C, reducing energy consumption by over 30%. The heating temperature between 200 and 300°C ensures complete evaporation of mercury under vacuum conditions while preventing equipment corrosion caused by high temperatures.

[0042] Refer to the attached Figure 3 As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater is shown. The activated carbon adsorption tower 51 is filled with coconut shell activated carbon, and the washing liquid in the alkaline washing tower 52 has a pH of ≥10 and a spray density of 20 to 40 liters / m2·hour. The coconut shell activated carbon has an adsorption efficiency of up to 99% for mercury vapor. The alkaline washing liquid with a pH of ≥10 can promote the removal of Hg 0 Oxidized to Hg 2+ And with OH - Form Hg(OH)2 precipitation to ensure that the exhaust gas meets the standards.

[0043] Refer to the attached Figure 2 , Attachment Figure 3 As shown, a multi-coupling device for recovering heavy metal mercury ions in petrochemical wastewater, wherein a first pipe 71 is connected between the filter 11 and the pH regulating tank 12, a second pipe 72 is connected between the pH regulating tank 12 and the electrochemical reaction tank 2, a third pipe 73 is connected between the electrochemical reaction tank 2 and the membrane separation unit 3, an eleventh pipe 711 is provided on the electrochemical reaction tank 2, a fourth pipe 74 is connected between the membrane separation unit 3 and the mercury recovery unit 4, a fifth pipe 75 is connected between the vacuum distillation device 41 and the condenser 42, a sixth pipe 76 is connected between the condenser 42 and the mercury collector 43, a seventh pipe 77 is connected between the condenser 42 and the activated carbon adsorption tower 51, and an eighth pipe 78 is connected between the activated carbon adsorption tower 51 and the alkaline washing tower 52.

[0044] Refer to the attached Figure 2 , Attachment Figure 3 As shown, a multi-coupling device for recovering heavy metal mercury ions in petrochemical wastewater is provided. A first pump 61 is provided in the first pipeline 71, a second pump 62 and a first valve 81 are provided in the second pipeline 72, a third pump 63 and a second valve 82 are provided in the third pipeline 73, a fourth pump 64 is provided in the fourth pipeline 74, a third valve 83 is provided in the fifth pipeline, a fourth valve 84 is provided in the sixth pipeline, a fifth valve 85 and the fifth pump 65 are provided in the seventh pipeline 77, and a seventh valve 87 is provided in the eleventh pipeline 711.

[0045] Refer to the attached Figure 2 , Attachment Figure 3 , Attachment Figure 4 , Attachment Figure 5 As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater includes an automatic control system 9. This system controls the opening and closing of pumps 1, 61, 62, 63, 64, 65, 66, and valves 81, 82, 83, 84, 85, and 86. The automatic control system 9 is electrically connected to a filter 11, a pH adjustment tank 12, an electrochemical reaction tank 2, a nanofiltration membrane 31, a reverse osmosis membrane 32, a vacuum distillation apparatus 41, a condenser 42, an activated carbon adsorption tower 51, an alkaline scrubber 52, and a backup activated carbon adsorption tower 54. The automatic control system 9 is used to collect real-time data on various process parameters (such as pH, voltage, and flow rate). The automatic control system 9 monitors and optimizes process parameters in real time to improve recovery efficiency and stability. It can automatically adjust parameters such as voltage, current, and flow rate based on process requirements, and can set alarms for parameter over-limits to promptly address abnormal situations.

[0046] Refer to the attached Figure 4As shown, a multi-coupling device for recovering heavy metal mercury ions from petrochemical wastewater includes a tail gas treatment unit 5 including a backup activated carbon adsorption tower 54. A ninth pipeline 79 connects the backup activated carbon adsorption tower 54 to the activated carbon adsorption tower 51, and a tenth pipeline 710 connects the backup activated carbon adsorption tower 54 to the alkaline scrubber 52. A mercury vapor analyzer 53 is installed in the eighth pipeline 78, and a sixth valve 86 and a sixth pump 66 are installed in the ninth pipeline 79. Petrochemical wastewater flowing out of the factory first enters the filter 11 for filtration. After flowing through the first pipeline 71, the first pump 61 regulates the rate at which the wastewater enters the pH adjustment tank 12 to prevent excessive pH fluctuations in the pH adjustment tank 12. When the pH in pH adjustment tank 12 reaches the set value (pH 6.5-8.0), first valve 81 is opened, and wastewater is drawn into electrochemical reaction tank 2 by pump 2. The anode of electrochemical reaction tank 2 produces oxygen and chlorine when treating the wastewater. When these gases reach a certain level, valve 77 is opened, allowing them to flow out through pipe 11 for treatment. A large amount of mercury is produced at the cathode of electrochemical reaction tank 2. This mercury can be collected by replacing the electrodes and cleaning the motor. After a period of time, pump 3 63 and valve 82 are opened, and the remaining wastewater flows through pipe 3 73 into membrane separation unit 3. Membrane separation unit 3 is used to further concentrate and separate the enriched mercury solution, improving recovery efficiency. The mercury-containing liquid retained by membrane separation unit 3 is then pumped by pump 4 64 and passed through pipe 4 74 into vacuum distillation unit 41. The concentrated mercury solution is vacuum distilled in a vacuum distillation unit 41 to separate high-purity mercury. The third valve 83 is opened, allowing mercury vapor to enter the condenser 42. After a period of time, the fourth valve 84 is opened, and the high-purity liquid mercury condensed in the condenser 42 enters the mercury collector 43 through the sixth pipe 76. After collection, the fourth valve 84 is closed. The fifth valve 85 and the fifth pump 65 are opened, and the remaining exhaust gas flows through the seventh pipe 77 and enters the activated carbon adsorption tower 51. After absorption by the activated carbon adsorption tower 51, the exhaust gas enters the eighth pipe 78. When the mercury vapor analyzer 53 in the eighth pipe 78 detects a mercury concentration of ≥0.04 mg / L, the sixth valve 86 and the sixth pump 66 are opened to activate the backup activated carbon adsorption tower 54, dispersing the exhaust gas into the backup activated carbon adsorption tower 54 for emergency adsorption treatment. This prevents mercury content in the wastewater from exceeding the standard in extreme cases, ensuring compliance with the national emission standard GB 30770-2014.

[0047] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0048] 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 do not impose any form of limitation on the implementation methods of the technology of the present invention. Any person skilled in the art 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. 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 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, there are objectively infinite specific structures. For ordinary technicians in this technical field, without departing from the principles of this application, they can also make several improvements, modifications or changes, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the inventive concept and technical solution to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A device for recovering heavy metal mercury ions from petrochemical wastewater by multiple coupling, characterized by: The invention comprises a pretreatment unit (1), an electrochemical reaction tank (2), a membrane separation unit (3), a mercury recovery unit (4) and an exhaust gas treatment unit (5) which are connected in sequence. The pretreatment unit (1) comprises a filter (11) and a pH adjustment tank (12). The electrochemical reaction tank (2) adopts a graphene / carbon nanotube composite electrode. The membrane separation unit (3) comprises a nanofiltration membrane (31) and a reverse osmosis membrane (32). The mercury recovery unit (4) comprises a vacuum distillation device (41) and a condenser (42). The condenser (42) is connected to a mercury collector (43). The exhaust gas treatment unit (5) comprises an activated carbon adsorption tower (51) and an alkaline washing tower (52).

2. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 1, characterized in that: The filter (11) is a microporous filter with a filtration accuracy of at least 1 micron. The pH adjustment tank (12) is provided with a feeder (121) and a pH sensor (122). The pH adjustment tank (12) is provided with a stirrer (123) with a stirring speed between 30 and 60 revolutions per minute.

3. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 1, characterized in that: The operating voltage of the electrochemical reaction tank (2) is between 1.5 and 3 volts, the current density is between 0.5 and 2 amperes per square decimeter, and the electrolyte flow rate is between 0.5 and 2 meters per second. The electrochemical reaction tank (2) is made of polypropylene, fiberglass or titanium alloy, and the electrode spacing is between 1 and 5 centimeters.

4. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 1, characterized in that: The nanofiltration membrane (31) has a pore size of less than 1 nanometer, an operating pressure of between 1 and 5 bar, and a flow rate of between 0.1 and 1 cubic meter per hour; the reverse osmosis membrane (32) has a pore size of less than 0.1 nanometer, an operating pressure of between 5 and 15 bar, and a flow rate of between 0.1 and 0.5 cubic meter per hour.

5. The device for recovering heavy metal mercury ions from petrochemical wastewater by multiple coupling according to claim 1, characterized in that: The vacuum degree of the vacuum distillation device (41) is between 0.1 and 1 torr, the heating temperature is between 200 and 300° C., and the distillation time is between 1 and 2 hours. The condenser (42) adopts a serpentine tube structure, and the cooling medium is circulating water or oil cooling.

6. The device for recovering heavy metal mercury ions from petrochemical wastewater by multiple coupling according to claim 1, characterized in that: The activated carbon adsorption tower (51) is filled with coconut shell activated carbon, the washing liquid in the alkaline washing tower (52) has a pH value of ≥10, and a spray density of 20 to 40 liters / square meter·hour.

7. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 1, characterized in that: A first pipe (71) is connected between the filter (11) and the pH adjustment tank (12), a second pipe (72) is connected between the pH adjustment tank (12) and the electrochemical reaction tank (2), a third pipe (73) is connected between the electrochemical reaction tank (2) and the membrane separation unit (3), an eleventh pipe (711) is provided on the electrochemical reaction tank (2), a fourth pipe (74) is connected between the membrane separation unit (3) and the mercury recovery unit (4), a fifth pipe (75) is connected between the vacuum distillation device (41) and the condenser (42), a sixth pipe (76) is connected between the condenser (42) and the mercury collector (43), a seventh pipe (77) is connected between the condenser (42) and the activated carbon adsorption tower (51), and an eighth pipe (78) is connected between the activated carbon adsorption tower (51) and the alkaline washing tower (52).

8. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 7, characterized in that: The first pipeline (71) is provided with a No. 1 pump (61), the second pipeline (72) is provided with a No. 2 pump (62) and a first valve (81), the third pipeline (73) is provided with a No. 3 pump (63) and a second valve (82), the fourth pipeline (74) is provided with a No. 4 pump (64), the fifth pipeline (75) is provided with a third valve (83), the sixth pipeline (76) is provided with a fourth valve (84), the seventh pipeline (77) is provided with a fifth valve (85) and the No. 5 pump (65), and the eleventh pipeline (711) is provided with a seventh valve (87).

9. The device for recovering heavy metal mercury ions from petrochemical wastewater according to claim 8, characterized in that: The tail gas treatment unit (5) includes a spare activated carbon adsorption tower (54), a ninth pipeline (79) is connected between the spare activated carbon adsorption tower (54) and the activated carbon adsorption tower (51), a tenth pipeline (710) is connected between the spare activated carbon adsorption tower (54) and the alkaline washing tower (52), a mercury vapor analyzer (53) is provided in the eighth pipeline (78), and a sixth valve (86) and a sixth pump (66) are provided in the ninth pipeline (79).

10. The device for recovering heavy metal mercury ions from petrochemical wastewater by multiple coupling according to claim 9, characterized in that: The invention comprises an automatic control system (9), wherein the automatic control system (9) can control the switching of a first pump (61), a second pump (62), a third pump (63), a fourth pump (64), a fifth pump (65), a sixth pump (66), a first valve (81), a second valve (82), a third valve (83), a fourth valve (84), a fifth valve (85), and a sixth valve (86); the automatic control system (9) is electrically connected to a filter (11), a pH regulating tank (12), an electrochemical reaction tank (2), a nanofiltration membrane (31), a reverse osmosis membrane (32), a vacuum distillation device (41), a condenser (42), an activated carbon adsorption tower (51), an alkaline washing tower (52), and a spare activated carbon adsorption tower (54), and is used to collect real-time data of various process parameters.

Images