A method and system for ultrasonic intensification of low-concentration vanadium solutions

Abstract

The application discloses a method for ultrasonic intensification treatment of low-concentration vanadium solution, which comprises the following steps: (1) filtering the vanadium-containing solution to be treated to remove the particulate suspensions in the vanadium solution; (2) adjusting the pH of the vanadium solution filtered in the step (1) to 4-8; (3) feeding the vanadium solution with the adjusted pH in the step (2) into a reactor and adding a vanadium removal agent; (4) starting a multi-frequency combined ultrasonic device to perform ultrasonic intensification treatment; and (5) performing solid-liquid separation to obtain a purified solution with a vanadium concentration less than 1 ppm.

Description

Technical Field

[0001] This invention relates to the fields of water treatment and hydrometallurgical technology, and in particular to a method and system for ultrasonically enhanced treatment of low-concentration vanadium solutions. Background Technology

[0002] With increasingly stringent environmental regulations, the emission standards for heavy metals in industrial wastewater are constantly being raised. Vanadium, as a toxic heavy metal, is commonly found in wastewater from industries such as steel, vanadium chemicals, and catalysts. For vanadium-containing solutions with low initial concentrations (1-50 ppm), such as end-of-pipe wastewater, polluted groundwater, and low-concentration process wastewater, the technical difficulty and economic cost of deep treatment to below 1 ppm are often higher than those for treating high-concentration wastewater. Existing technologies for treating low-concentration vanadium solutions mainly include adsorption, ion exchange, and membrane separation. Taking adsorption as an example, the difficulty in treating low-concentration vanadium-containing wastewater is mainly due to the following reasons: 1. At high concentrations, the large number of vanadium ions in the solution creates a strong concentration gradient with the adsorbent surface, which facilitates the rapid and large-scale diffusion of vanadium ions to the adsorbent surface. If the concentration of vanadium ions is low, the concentration gradient is gentle, resulting in slow diffusion. 2. A microscopic static liquid film, or boundary layer, exists on the surface of the adsorbent particles. At high concentrations, the strong concentration difference facilitates the penetration of vanadium ions through the boundary layer to contact the active sites on the adsorbent particle surface. At lower concentrations, it takes longer for vanadium ions to reach the active sites inside the adsorbent. Furthermore, ion exchange methods are prone to resin fouling, resulting in large volumes of regeneration wastewater and high operating costs, which are unfavorable for industrial production. Membrane separation methods require high pretreatment standards, suffer from severe membrane fouling, and require further treatment of the concentrate.

[0003] Ultrasonic enhancement technology, as an efficient physicochemical enhancement method, has been proven to significantly improve mass transfer and reaction kinetics. However, existing ultrasonic processing equipment mostly adopts a single-frequency, single-power design, which limits its enhancement effect on vanadium in low-concentration systems and results in uneven energy distribution, easily creating processing dead zones. More importantly, current technologies lack a solution that systematically integrates dedicated equipment design with optimized process parameters, making it difficult to achieve economical and efficient deep processing of low-concentration vanadium solutions.

[0004] Therefore, developing an ultrasonic strengthening device and its supporting process specifically designed for low-concentration vanadium solutions to achieve low-energy consumption and high-efficiency deep vanadium removal is of great practical significance and application value. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for ultrasonically enhanced treatment of low-concentration vanadium solutions.

[0006] The objective of this invention is achieved through the following technical solution: a method for ultrasonically enhanced treatment of low-concentration vanadium solutions, comprising the following steps: (1) Filter the vanadium-containing solution to be treated to remove particulate matter suspended in the vanadium solution; (2) Adjust the pH of the vanadium solution filtered in step (1) to 4-8; (3) The vanadium solution after pH adjustment in step (2) is fed into the reactor, and vanadium removal agent is added at the same time; (4) Turn on multi-frequency combined ultrasound and perform ultrasound enhancement treatment; (5) Solid-liquid separation was performed to obtain a purified solution with a vanadium concentration of less than 1 ppm.

[0007] In step (1), the vanadium content in the vanadium-containing solution to be treated is 1 to 50 ppm.

[0008] Step (3) The vanadium removal agent is one of titanium-based adsorbent and modified bentonite, with a dosage of 0.2-5 g / L. The titanium-based adsorbent is TiO2•xH2O, and the modified bentonite is modified bentonite loaded with nano-iron oxides. The titanium-based adsorbent has a good adsorption affinity for vanadium in the solution, but it lacks adsorption power for low-concentration vanadium and has a long adsorption time. By adjusting the ultrasonic frequency and power, it is beneficial to enhance boundary mass transfer, promote the diffusion of vanadium ions inside the adsorbent, and shorten the processing time. The modified bentonite is modified bentonite attached to nano-iron oxides, which is beneficial to recover it by using iron adsorption. Although the modified bentonite has a good adsorption affinity for vanadium in the solution, it is easy to agglomerate after absorbing water. By adjusting the ultrasonic frequency and power, the agglomerates can be effectively dispersed, exposing more active adsorption sites.

[0009] The reactor used in step (3) is a continuous tubular reactor or a trough reactor.

[0010] Step (4) Activating multi-frequency combined ultrasound includes the following stages: First stage: The ultrasonic frequency is 20-25kHz, the power density is 60-80W / L, and the residence time is 5-10min. The first stage uses low-frequency ultrasound of 20-25kHz. The main purposes are: first, to break up adsorbent agglomerates; second, to peel off the adsorbed layer and expose new active sites; and third, to generate physical stirring. The second stage: the ultrasonic frequency is 40-80 kHz, the power density is 20-40 W / L, and the residence time is 20-40 min; the second stage uses 40-80 kH of ultrasound. Increasing the ultrasonic frequency is beneficial to enhance boundary mass transfer and promote the diffusion of vanadium ions inside the adsorbent. The third stage: the ultrasonic frequency is 20-25 kHz, the power density is 10-20 W / L, and the residence time is 5-10 min; pulsed ultrasound is used in this stage with a duty cycle of 50%. The stirring effect of the low-frequency ultrasound at 20-25 kHz in the third stage helps to avoid sedimentation and adhesion of the vanadium removal agent to the wall. Pulsed ultrasound is used, for example, ultrasound for 1 second followed by a 1 second pause, which can generate peristaltic force, which is beneficial to solid-liquid separation and reduces reactor blockage.

[0011] This invention also provides a system for ultrasonically enhanced treatment of low-concentration vanadium, comprising a feeding unit, a feeding unit, an ultrasonic reaction unit, and a discharging unit; the feeding unit is connected to the ultrasonic reaction unit; the feeding unit includes a feed pump, a vanadium solution flow meter, and a filter; the feeding unit is connected to the ultrasonic reaction unit; the feeding unit includes a pH adjuster storage tank, a vanadium removal agent storage tank, a pH adjuster metering pump, a vanadium removal agent metering pump, and an online pH meter; the ultrasonic reaction unit is a continuous tubular reactor or a trough reactor; the discharging unit is connected to the outlet of the ultrasonic reaction unit; the discharging unit includes a discharging pump and a slurry buffer tank.

[0012] The continuous tubular reactor includes, in sequence along the material flow direction, a dispersion section, an adsorption section, a corrugated section, and a separation section; the dispersion section and the adsorption section are connected by a first variable diameter flange connector; the adsorption section and the corrugated section are connected by a second variable diameter flange connector; and the corrugated section and the dispersion section are connected by a third variable diameter flange connector.

[0013] The dispersion tube section is equipped with a spiral stirrer; the inner diameter of the dispersion tube section is 50-55 mm, the length of the dispersion tube section is 1-2 m, and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals on the dispersion tube section; the adsorption tube section is equipped with baffles at intervals; the inner diameter of the adsorption tube section is 80-100 mm, the length of the adsorption tube section is 5-10 m, and an array of ultrasonic transducers with a vibration frequency of 40-80 kHz is installed at intervals on the adsorption tube section; the corrugated tube section is a corrugated pipe with an inner diameter of 100-120 mm; the length of the corrugated tube section is 150-300 mm; the separation tube section has an inner diameter of 120-150 mm, a length of 1-2 m, is inclined at 5°-10°, and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals on the separation tube section.

[0014] The purpose of the dispersion section is to disperse and activate, and prevent agglomerates from entering the adsorption section. Therefore, the inner diameter of the dispersion section is set to a thin tube of 50-55 mm, which is conducive to strengthening the shearing effect. The tube length is 1-2 m, and the residence time of the reactants in the dispersion section is 5-10 min. A spiral stirrer is set in the dispersion section. First, it can play a conveying role, sending the materials in the dispersion section into the adsorption section. Second, the spiral blades can further improve the shearing force and work synergistically with ultrasound to further disperse the agglomerates. A 20-25 kHz ultrasonic transducer array is set in the dispersion section, corresponding to the first stage of process step (4), which is mainly to disperse and promote the diffusion of vanadium ions in low-concentration vanadium solution.

[0015] Furthermore, the top of the dispersion pipe section is equipped with a feed inlet, a feeding port, and a pH adjuster inlet for connection to the feeding unit and the feeding unit; a motor is installed at one end of the dispersion pipe section, and the other end of the dispersion pipe section is connected to the first reducing flange connector; the first reducing flange connector includes a first flange plate, a reducing pipe, and a second flange plate; a mounting plate is installed in the middle of the first flange plate for mounting bearings; several flow holes are distributed planetarily around the outer periphery of the mounting plate for material passage; the smaller diameter end of the reducing pipe is connected to the first flange plate; the larger diameter end of the reducing pipe is connected to the second flange plate; several flow holes are provided on the first flange plate, which is beneficial for further shearing and dispersion.

[0016] The purpose of the adsorption tube section is to enhance adsorption. By increasing the tube diameter and installing a first baffle inside the tube, the linear velocity is reduced, thereby extending the residence time and improving the selective adsorption of vanadium ions by the vanadium removal agent. An array of 40-80 kHz ultrasonic transducers is installed at intervals on the adsorption tube section, corresponding to the second stage of process step (4), to enhance boundary mass transfer and promote the diffusion of vanadium ions inside the adsorbent. The first baffle also helps to reflect and scatter ultrasonic waves, eliminating the "dead zone" and "standing wave" phenomenon of the ultrasonic field, and ensuring that each part of the solution is subjected to uniform ultrasonic action.

[0017] The purpose of the corrugated pipe section is to provide a flexible connection. The flexible connection has two main functions: First, the ultrasonic transducers in the adsorption pipe section and the separation pipe section have different frequencies. The flexible connection replaces the rigid connection, which can avoid vibration interference and prevent the rigid structure from loosening. Second, the separation pipe section has a certain tilt angle. The flexible connection is beneficial to the structural stability when the separation pipe section is installed at an angle.

[0018] The purpose of the separation pipe section is to prevent sedimentation, blockage, and wall adhesion. Further enlarging the inner diameter of the separation pipe section reduces the flow velocity, while simultaneously tilting it at a certain angle. Combined with the peristaltic force generated by pulsed ultrasound, this further promotes material movement and prevents sedimentation, blockage, and wall adhesion. Installing a 20-25kHz ultrasonic transducer array on the separation pipe section corresponds to the third stage of process step (4). Utilizing the stirring effect of low-frequency ultrasound and the peristaltic effect of pulsed ultrasound, material movement is promoted, preventing sedimentation and blockage.

[0019] The trough reactor includes a trough body; an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals at the bottom of the trough body; an array of ultrasonic transducers with a vibration frequency of 40-80 kHz and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz are alternately installed on the side walls of the trough body; a baffle is provided on the side walls of the trough body; a stirring mechanism is provided inside the trough body; the stirring mechanism includes a forward and reverse motor, a threaded shaft, a moving ring, and blades; the motor drives the threaded shaft to rotate forward or reverse; the moving ring is movably mounted on the threaded shaft; the inner wall of the moving ring is provided with an internal thread that mates with the threaded shaft; the blades are provided on the outer wall of the moving ring.

[0020] An ultrasonic transducer array with a vibration frequency of 20-25 kHz at the bottom of the tank is activated after the reactants are added, corresponding to the first stage of process step (4). This is beneficial for breaking up the agglomerates that have settled to the bottom of the tank. An ultrasonic transducer array with a vibration frequency of 40-80 kHz and an ultrasonic transducer array with a vibration frequency of 20-25 kHz are installed alternately on the side wall of the tank. These arrays are activated in the second and third stages of process step (4), respectively, to promote the diffusion of vanadium ions inside the vanadium removal agent. The stirring mechanism installed in the tank drives the spiral shaft to rotate in both directions via a forward and reverse motor, causing the moving ring to move up and down along the spiral shaft. This is beneficial for lifting up the agglomerates that have settled at the bottom. The blades rotate and move along the spiral shaft with the moving ring, which is beneficial for generating shear force and dispersing the agglomerates.

[0021] The present invention provides a system for ultrasonically enhanced treatment of low-concentration vanadium, which also includes an automatic control system: a PLC or industrial computer is electrically connected to the feed pump, metering pump, ultrasonic reactor array, online pH meter, temperature sensor, etc., to realize the full-process automated control and data acquisition. The control system can automatically adjust parameters such as ultrasonic power, reagent dosage, and reaction time according to the fluctuation of influent water quality to ensure that the effluent meets the standards stably.

[0022] The present invention has the following advantages: 1. Strong deep purification capability: Specifically optimized for low-concentration vanadium solutions, it can further treat vanadium-containing solutions with initial concentrations as low as 1-50 ppm to below 1 ppm, meeting the most stringent emission or reuse requirements.

[0023] 2. High processing efficiency: Multi-frequency combined ultrasound greatly enhances mass transfer and reaction kinetics, reducing the processing time of traditional adsorption / precipitation processes by more than 50%.

[0024] 3. Low energy and chemical consumption: Precise energy input and optimized flow field design improve the utilization efficiency of ultrasonic energy; enhanced mass transfer enables the treatment target to be achieved with a lower dosage of chemical, reducing operating costs.

[0025] 3. Stable and reliable operation: The automatic control system realizes closed-loop control throughout the entire process, has strong adaptability, and ensures stable effluent quality.

[0026] 4. High equipment integration: The equipment has a compact structure, small footprint, can operate continuously, and is easy to implement in industrial applications and automated management. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the ultrasonically enhanced vanadium system in Example 2.

[0028] Figure 2 This is a schematic diagram of the continuous tubular reactor structure in Example 2.

[0029] Figure 3 This is a schematic diagram of the first variable diameter flange connection part in the ultrasonic strengthening treatment system for low-concentration vanadium in Example 2.

[0030] Figure 4 This is a side view of the first variable-diameter flange connector in the ultrasonically enhanced vanadium treatment system of Example 2. Figure 5 This is a schematic diagram of the ultrasonically enhanced vanadium system in Example 3.

[0031] Figure 6 This is a partial structural schematic diagram of the ultrasonically enhanced vanadium system in Example 3.

[0032] In the diagram: 1. Feed pump; 2. Vanadium solution flow meter; 3. Filter; 4. pH adjuster storage tank; 5. Vanadium removal reagent storage tank; 6. pH adjuster metering pump; 7. Vanadium removal reagent metering pump; 8. Discharge pump; 9. Slurry buffer tank; 10. Continuous tubular reactor; 101. Dispersion section; 102. Adsorption section; 103. Corrugated section; 104. Separation section; 105. First reducing flange connector; 1051. First flange plate; 1052. Second flange plate; 1053. Mounting plate; 1054. Flow hole; 106. Second reducing flange connector; 107. Third reducing flange connector; 108. Spiral agitator; 109. First baffle plate; 11. Tank reactor; 111. Tank body; 113. Second spoiler; 114. Reverse motor; 115. Threaded shaft; 116. Moving ring; 117. Blade; 12. Ultrasonic transducer array. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0037] Example 1: A method for ultrasonically enhanced treatment of low-concentration vanadium solution, comprising the following steps: (1) Filter the vanadium-containing solution to be treated to remove particulate matter suspended in the vanadium solution; (2) Adjust the pH of the vanadium solution filtered in step (1) to 4-8; (3) The vanadium solution after pH adjustment in step (2) is fed into the reactor, and vanadium removal agent is added at the same time; (4) Turn on multi-frequency combined ultrasound and perform ultrasound enhancement treatment; (5) Solid-liquid separation was performed to obtain a purified solution with a vanadium concentration of less than 1 ppm.

[0038] In step (1), the vanadium content in the vanadium-containing solution to be treated is 1 to 50 ppm.

[0039] Step (3) The vanadium removal agent is one of titanium-based adsorbent and modified bentonite, with a dosage of 0.2-5 g / L. The titanium-based adsorbent is TiO2•xH2O, and the modified bentonite is modified bentonite loaded with nano-iron oxides. The titanium-based adsorbent has a good adsorption affinity for vanadium in the solution, but it lacks adsorption power for low-concentration vanadium and has a long adsorption time. By adjusting the ultrasonic frequency and power, it is beneficial to enhance boundary mass transfer, promote the diffusion of vanadium ions inside the adsorbent, and shorten the processing time. The modified bentonite is modified bentonite attached to nano-iron oxides, which is beneficial to recover it by using iron adsorption. Although the modified bentonite has a good adsorption affinity for vanadium in the solution, it is easy to agglomerate after absorbing water. By adjusting the ultrasonic frequency and power, the agglomerates can be effectively dispersed, exposing more active adsorption sites.

[0040] The reactor used in step (3) is either a continuous tubular reactor 10 or a trough reactor 11.

[0041] Step (4) Activating multi-frequency combined ultrasound includes the following stages: First stage: The ultrasonic frequency is 20-25kHz, the power density is 60-80W / L, and the residence time is 5-10min. The first stage uses low-frequency ultrasound of 20-25kHz. The main purposes are: first, to break up adsorbent agglomerates; second, to peel off the adsorbed layer and expose new active sites; and third, to generate physical stirring. The second stage: the ultrasonic frequency is 40-80 kHz, the power density is 20-40 W / L, and the residence time is 20-40 min; the second stage uses 40-80 kH of ultrasound. Increasing the ultrasonic frequency is beneficial to enhance boundary mass transfer and promote the diffusion of vanadium ions inside the adsorbent. The third stage: the ultrasonic frequency is 20-25 kHz, the power density is 10-20 W / L, and the residence time is 5-10 min; pulsed ultrasound is used in this stage with a duty cycle of 50%. The stirring effect of the low-frequency ultrasound at 20-25 kHz in the third stage helps to avoid sedimentation and adhesion of the vanadium removal agent to the wall. Pulsed ultrasound is used, for example, ultrasound for 1 second followed by a 1 second pause, which can generate peristaltic force, which is beneficial to solid-liquid separation and reduces reactor blockage.

[0042] Example 2: As Figure 1-4As shown, a system for ultrasonically enhanced treatment of low-concentration vanadium includes a feeding unit, a feeding unit, an ultrasonic reaction unit, and a discharging unit. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a feed pump 1, a vanadium solution flow meter 2, and a filter 3. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a pH adjuster storage tank 4, a vanadium removal agent storage tank 5, a pH adjuster metering pump 6, a vanadium removal agent metering pump 7, and an online pH meter. The ultrasonic reaction unit is a continuous tubular reactor 10. The discharging unit is connected to the outlet of the ultrasonic reaction unit. The discharging unit includes a discharging pump 8 and a slurry buffer tank 9.

[0043] The continuous tubular reactor 10 includes, in sequence along the material flow direction, a dispersion section 101, an adsorption section 102, a corrugated section 103, and a separation section 104; the dispersion section 101 and the adsorption section 102 are connected by a first variable diameter flange connector 105; the adsorption section 102 and the corrugated section 103 are connected by a second variable diameter flange connector 106; and the corrugated section 103 and the separation section 104 are connected by a third variable diameter flange connector 107.

[0044] The dispersion tube section 101 is internally equipped with a spiral stirrer 108; the dispersion tube section 101 has an inner diameter of 50-55 mm and a length of 1-2 m; an ultrasonic transducer array 12 with a vibration frequency of 20-25 kHz is installed at intervals on the dispersion tube section 101; the adsorption tube section 102 is internally equipped with first baffles 109 at intervals; the adsorption tube section 102 has an inner diameter of 80-100 mm and a length of 5-10 m; an adsorption tube section 102 is equipped with baffles with a vibration frequency of 40-80 kHz at intervals. The system includes a kHz ultrasonic transducer array 12; a corrugated pipe section 103 with an inner diameter of 100-120 mm and a length of 150-300 mm; a separation pipe section 104 with an inner diameter of 120-150 mm and a length of 1-2 m, inclined at 5°-10°; and an ultrasonic transducer array 12 with a vibration frequency of 20-25 kHz installed at intervals on the separation pipe section.

[0045] The purpose of the dispersion section 101 is to disperse and activate, and to prevent agglomerates from entering the adsorption section 102. Therefore, the inner diameter of the dispersion section 101 is set to a thin tube of 50-55 mm, which is conducive to strengthening the shearing action. The tube length is 1-2 m, and the residence time of the reactants in the dispersion section 101 is 5-10 min. A spiral stirrer 108 is set in the dispersion section 101. First, it can play a conveying role, sending the material in the dispersion section 101 into the adsorption section 102. Second, the spiral blades 117 can further improve the shearing force and work synergistically with ultrasound to further disperse the agglomerates. An ultrasonic transducer array 12 with a vibration frequency of 20-25 kHz is set in the dispersion section 101, which corresponds to the first stage of process step (4), mainly to disperse and promote the diffusion of vanadium ions in the low-concentration vanadium solution.

[0046] Furthermore, the top of the dispersion section 101 is provided with a feed inlet, a feeding port, and a pH adjuster feeding port for connection to the feeding unit and the feeding unit; a motor is provided at one end of the dispersion section 101, and the other end of the dispersion section 101 is connected to the first reducing flange connector 105; the first reducing flange connector 105 includes a first flange plate 1051, a reducing pipe, and a second flange plate 1052; a mounting plate 1053 is provided in the middle of the first flange plate for mounting bearings; a plurality of flow holes 1054 are planetarily distributed on the outer periphery of the mounting plate 1053 for material passage; the smaller diameter end of the reducing pipe is connected to the first flange plate 1051; the larger diameter end of the reducing pipe is connected to the second flange plate 1052; a plurality of flow holes 1054 are provided on the first flange plate 1051, which is beneficial for further shearing and dispersion when the material passes through.

[0047] The purpose of the adsorption tube section 102 is to enhance adsorption. By increasing the tube diameter and installing the first baffle 109 inside the tube, the linear velocity is reduced, thereby extending the residence time and improving the selective adsorption of vanadium ions by the vanadium removal agent. An ultrasonic transducer array 12 with a vibration frequency of 40-80 kHz is installed at intervals on the adsorption tube section 102, corresponding to the second stage of process step (4), to enhance boundary mass transfer and promote the diffusion of vanadium ions inside the adsorbent. The first baffle 109 also helps to reflect and scatter ultrasonic waves, eliminate the "dead zone" and "standing wave" phenomenon of the ultrasonic field, and ensure that each part of the solution is subjected to uniform ultrasonic action.

[0048] The purpose of the corrugated pipe section 103 is to provide a flexible connection. The flexible connection has two main functions: First, the ultrasonic transducer array 12 set in the adsorption pipe section 102 and the separation pipe section 104 has different vibration frequencies. The flexible connection replaces the rigid connection, which can avoid vibration interference and prevent the rigid structure from loosening. Second, the separation pipe section 104 has a certain tilt angle. The flexible connection is beneficial to the structural stability when the separation pipe section 104 is installed at an angle.

[0049] The purpose of the separation tube section 104 is to prevent sedimentation, blockage, and wall adhesion. By further enlarging the inner diameter of the separation tube section 104 and reducing the flow velocity, and by tilting it at a certain angle, combined with the peristaltic force generated by pulsed ultrasound, the material movement can be further promoted, avoiding sedimentation, blockage, and wall adhesion. An ultrasonic transducer array 12 with a vibration frequency of 20-25 kHz is installed on the separation tube section 104, corresponding to the third stage of process step (4). The stirring effect of low-frequency ultrasound and the peristaltic effect of pulsed ultrasound are used to promote material movement and avoid sedimentation and blockage.

[0050] Example 3: As Figure 5-6 As shown, a system for ultrasonically enhanced treatment of low-concentration vanadium includes a feeding unit, a feeding unit, an ultrasonic reaction unit, and a discharging unit. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a feed pump 1, a vanadium solution flow meter 2, and a filter 3. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a pH adjuster storage tank 4, a vanadium removal agent storage tank 5, a pH adjuster metering pump 6, a vanadium removal agent metering pump 7, and an online pH meter. The ultrasonic reaction unit is a tank reactor 11. The discharging unit is connected to the outlet of the ultrasonic reaction unit. The discharging unit includes a discharging pump 8 and a slurry buffer tank 9.

[0051] The trough reactor 11 includes a trough body 111; an array of ultrasonic transducers 12 with a vibration frequency of 20-25 kHz is installed at intervals at the bottom of the trough body 111; an array of ultrasonic transducers 12 with a vibration frequency of 40-80 kHz and an array of ultrasonic transducers 12 with a vibration frequency of 20-25 kHz are alternately installed on the sidewalls of the trough body 111; a second baffle 113 is provided on the sidewalls of the trough body 111; a stirring mechanism is provided inside the trough body 111; the stirring mechanism includes a forward and reverse motor 114, a threaded shaft 115, a moving ring 116, and blades 117; the motor drives the threaded shaft 115 to rotate forward or reverse; the moving ring 116 is slidably fitted on the threaded shaft 115; the inner wall of the moving ring 116 is provided with an internal thread that mates with the threaded shaft 115; and the blades 117 are provided on the outer wall of the moving ring 116.

[0052] The ultrasonic transducer array 12 with a vibration frequency of 20-25kHz at the bottom of the tank 111 is turned on after the reactant is added, corresponding to the first stage of process step (4), which is conducive to breaking up the agglomerates that have settled to the bottom of the tank. The ultrasonic transducer array 12 with a vibration frequency of 40-80 kHz and the ultrasonic transducer array 12 with a vibration frequency of 20-25kHz are installed alternately on the side wall of the tank 111, and are turned on in the second and third stages of process step (4), respectively, to promote the diffusion of vanadium ions inside the vanadium removal agent. The stirring mechanism set in the tank 111 drives the threaded shaft 115 to rotate in both directions through the forward and reverse motor 114, so that the moving ring 116 moves up and down along the threaded shaft 115, which is conducive to lifting up the agglomerates that have settled at the bottom. The blade 117 moves along the moving ring on the threaded shaft 115, which is conducive to generating shear force and dispersing the agglomerates.

[0053] Example 4: Treatment of low-concentration vanadium-containing wastewater from a chemical plant The wastewater discharged from a chemical plant contains 25 ppm of vanadium, a small amount of suspended solids, and has a pH of 7.2.

[0054] The system for ultrasonically enhanced treatment of low-concentration vanadium, as described in Example 2, wherein: Dispersion section 101 inner diameter: 50 mm; Dispersion section 101 length: 1 m; Dispersion section 101 residence time: 5 min; Ultrasonic frequency: 25 kHz; Power density: 80 W / L Inner diameter of adsorption tube section 102: 80 mm; Length of adsorption tube section 102: 8 m; Residence time of adsorption tube section 102: 40 min; Ultrasonic frequency: 80 kHz; Power density: 30 W / L Corrugated pipe section 103 inner diameter: 100mm; Corrugated pipe section 103 length: 200mm; Inner diameter of separation section 104: 120 mm; Length of separation section 104: 1.5 m; Residence time of separation section 104: 10 min; Ultrasonic frequency: 20 kHz; Power density: 20 W / L; Pulsed ultrasound with a duty cycle of 50% is used in this section. The process parameters are as follows: pH adjustment: Add dilute sulfuric acid to adjust the feed pH to 4.5; Vanadium removal agent: Titanium-based adsorbent (TiO2•xH2O) was used, with a dosage of 0.8 g / L; Operating results: The average vanadium concentration in the effluent, as analyzed by ICP-MS, was 0.65 ppm, consistently below 1 ppm.

[0055] Comparative Example 1: The same process parameters as in Example 4 were used, except that only a conventional mechanical stirring tank was used, and no ultrasound was introduced. The stirring speed was 200 rpm.

[0056] Results: After 45 minutes of operation, the vanadium concentration in the effluent was 8.3 ppm, far below the target of 1 ppm. The retention time was extended to 120 minutes, and the vanadium concentration in the effluent decreased to 2.1 ppm, but was still higher than 1 ppm.

[0057] Comparative Example 2: The same process parameters as in Example 4 were used, except that the diameter of the continuous tubular reactor 10 remained unchanged. Ultrasonic transducers were spaced along the tube wall at intervals: 0–1 m segment, the ultrasonic transducer vibration frequency was 25 kHz, the power density was 80 W / L, and the ultrasonic time was 5 min; 2–10 m segment, the ultrasonic transducer vibration frequency was 80 kHz, the power density was 30 W / L, and the ultrasonic time was 40 min; third stage: the ultrasonic transducer vibration frequency was 20 kHz, the power density was 20 W / L, and the ultrasonic time was 10 min; pulsed ultrasound with a duty cycle of 50% was used in this stage.

[0058] Results: The vanadium concentration in the effluent was 3.51 ppm, which did not meet the target of 1 ppm.

[0059] Comparative Example 3: The same process parameters as in Example 4 were used, except that the dispersion section 101, adsorption section 102, corrugated section 103, and separation section 104 all used 25kHz ultrasound with a power density of 80W / L.

[0060] Results: The vanadium concentration in the effluent was 5.20 ppm, which did not meet the target of 1 ppm.

[0061] Comparative Example 4: Using the same process parameters as Example 4, the diameter of the continuous tubular reactor 10 remained unchanged, and ultrasonic transducers were spaced apart along the tube axis. The ultrasonic frequency throughout the reaction was 25 kHz, and the power density was 80 W / L.

[0062] Results: The vanadium concentration in the effluent was 7.41 ppm, which did not meet the target of 1 ppm.

[0063] Example 5: Remediation of Vanadium-Contaminated Groundwater The groundwater at a certain site is contaminated with vanadium, with a vanadium concentration of 8 ppm and a pH of 6.5.

[0064] The system for ultrasonically enhanced treatment of low-concentration vanadium, as described in Example 3, wherein: The bottom of the tank 111 is equipped with an array of 25kHz ultrasonic transducers 12 with a power density of 100 W / L; the sidewalls of the tank 111 are equipped with an array of 80kHz ultrasonic transducers 12 with a power density of 100 W / L, and the sidewalls are also equipped with an array of 20kHz ultrasonic transducers 12 with a power density of 100 W / L.

[0065] The process parameters are as follows: Single batch water treatment capacity: 1.8m³ 3 ; pH adjustment: Add NaOH to adjust the feed pH to 7.5; Vanadium removal agent: Modified bentonite (supported with nano-iron oxides) was used, with a dosage of 0.5 g / L; Results: After the reaction was completed, the supernatant was allowed to stand for 30 minutes. The vanadium concentration was 0.4 ppm. The filtered water met the standard.

[0066] Comparative Example 6: The same process parameters as in Example 5 were used, except that only a conventional mechanical stirring tank was used, and no ultrasound was introduced. The stirring speed was 200 rpm.

[0067] Results: After the reaction was completed and the mixture was allowed to stand for 30 minutes, the vanadium concentration in the supernatant was 4.9 ppm, which did not reach the target of 1 ppm.

[0068] Comparative Example 7: The same process parameters as in Example 5 were used, except that the vibration frequency of the ultrasonic transducers on the side wall and bottom of the tank 111 was 25 kHz and the power density was 300 W / L.

[0069] Results: After the reaction was completed and the mixture was allowed to stand for 30 minutes, the vanadium concentration in the supernatant was 3.7 ppm, which did not reach the target of 1 ppm.

[0070] Example 6: Drug Reuse Test Referring to Example 5, the separated modified bentonite was regenerated by acid washing (0.1 mol / L HCl, ultrasonic-assisted regeneration for 5 min) and reused for the next batch treatment. This process was repeated 5 times, with vanadium concentrations in the effluent of each treatment being 0.4 ppm, 0.5 ppm, 0.6 ppm, 0.7 ppm, and 0.9 ppm, respectively, all below 1 ppm. This demonstrates that some of the vanadium removal reagent can be reused, further reducing operating costs.

[0071] in conclusion The above embodiments demonstrate that the ultrasonic-enhanced treatment method and system for low-concentration vanadium solutions provided by the present invention, through multi-frequency combined ultrasound and optimized equipment structure, can efficiently and stably treat low-concentration vanadium-containing solutions to below 1 ppm, which is significantly superior to traditional processes and has extremely high industrial application value and promotion prospects.

[0072] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for ultrasonically enhanced treatment of low-concentration vanadium solutions, characterized in that, Includes the following steps: (1) Filter the vanadium-containing solution to be treated to remove particulate matter suspended in the vanadium solution; (2) Adjust the pH of the vanadium solution filtered in step (1) to 4-8; (3) The vanadium solution after pH adjustment in step (2) is fed into the reactor, and vanadium removal agent is added at the same time; (4) Turn on multi-frequency combined ultrasound and perform ultrasound enhancement treatment; (5) Solid-liquid separation was performed to obtain a purified solution with a vanadium concentration of less than 1 ppm.

2. The method for ultrasonically enhanced treatment of low-concentration vanadium solution according to claim 1, characterized in that: In step (1), the vanadium content in the vanadium-containing solution to be treated is 1 to 50 ppm.

3. The method for ultrasonically enhanced treatment of low-concentration vanadium solution according to claim 1, characterized in that: Step (3) The vanadium removal agent is one of titanium-based adsorbent and modified bentonite, and the dosage is 0.2-5 g / L.

4. The method for ultrasonically enhanced treatment of low-concentration vanadium solution according to claim 1, characterized in that: The reactor used in step (3) is a continuous tubular reactor or a trough reactor.

5. The method for ultrasonically enhanced treatment of low-concentration vanadium solution according to claim 1, characterized in that: Step (4) Activating multi-frequency combined ultrasound includes the following stages: First stage: Ultrasonic frequency 20-25kHz, power density 60-80W / L, residence time 5-10min; Second stage: Ultrasonic frequency 40-80kHz, power density 20-40W / L, residence time 20-40min; The third stage: the ultrasonic frequency is 20-25 kHz, the power density is 10-20 W / L, and the residence time is 5-10 min; pulsed ultrasound is used in this stage with a duty cycle of 50%.

6. A system for ultrasonically enhanced treatment of low-concentration vanadium, characterized in that: The method for ultrasonically enhanced treatment of low-concentration vanadium solutions according to any one of claims 1-5.

7. The system for ultrasonically enhanced treatment of low-concentration vanadium according to claim 6, characterized in that, The reactor comprises a feeding unit, a feeding unit, an ultrasonic reaction unit, and a discharging unit. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a feed pump, a vanadium solution flow meter, and a filter. The feeding unit is connected to the ultrasonic reaction unit. The feeding unit includes a pH adjuster storage tank, a vanadium removal agent storage tank, a pH adjuster metering pump, a vanadium removal agent metering pump, and an online pH meter. The ultrasonic reaction unit is a continuous tubular reactor or a trough reactor. The discharging unit is connected to the outlet of the ultrasonic reaction unit. The discharging unit includes a discharging pump and a slurry buffer tank.

8. The system for ultrasonically enhanced treatment of low-concentration vanadium according to claim 7, characterized in that: The continuous tubular reactor includes, in sequence along the material flow direction, a dispersion section, an adsorption section, a corrugated section, and a separation section; the dispersion section and the adsorption section are connected by a first variable diameter flange connector; the adsorption section and the corrugated section are connected by a second variable diameter flange connector; and the corrugated section and the separation section are connected by a third variable diameter flange connector.

9. The system for ultrasonically enhanced treatment of low-concentration vanadium according to claim 8, characterized in that: The dispersion tube section is equipped with a spiral stirrer; the inner diameter of the dispersion tube section is 50-55 mm, the length of the dispersion tube section is 1-2 m, and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals on the dispersion tube section; the adsorption tube section is equipped with baffles at intervals; the inner diameter of the adsorption tube section is 80-100 mm, the length of the adsorption tube section is 5-10 m, and an array of ultrasonic transducers with a vibration frequency of 40-80 kHz is installed at intervals on the adsorption tube section; the corrugated tube section is a corrugated pipe with an inner diameter of 100-120 mm; the length of the corrugated tube section is 150-300 mm; the separation tube section has an inner diameter of 120-150 mm, a length of 1-2 m, is inclined at 5°-10°, and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals on the separation tube section.

10. The system for ultrasonically enhanced treatment of low-concentration vanadium according to claim 7, characterized in that: The trough reactor includes a trough body; an array of ultrasonic transducers with a vibration frequency of 20-25 kHz is installed at intervals at the bottom of the trough body; an array of ultrasonic transducers with a vibration frequency of 40-80 kHz and an array of ultrasonic transducers with a vibration frequency of 20-25 kHz are alternately installed on the side walls of the trough body; a baffle is provided on the side walls of the trough body; a stirring mechanism is provided inside the trough body; the stirring mechanism includes a forward and reverse motor, a threaded shaft, a moving ring, and blades; the motor drives the threaded shaft to rotate forward or reverse; the moving ring is movably mounted on the threaded shaft; the inner wall of the moving ring is provided with an internal thread that mates with the threaded shaft; the blades are provided on the outer wall of the moving ring.

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