A liquid composite thallium removal agent and its preparation method and application

Abstract

The present application relates to water treatment technology, and specifically to a liquid composite thallium remover, a preparation method and application thereof, wherein the liquid composite thallium remover is a first mixed solution obtained by mixing a soluble titanium salt with dilute sulfuric acid, and then adding an adsorption carrier and a titanium salt dispersion catalyst to the first mixed solution to obtain a second mixed solution; the second mixed solution is heated to boiling, then refluxed and cooled, and the pH is adjusted to a weak alkaline state. The present invention also discloses a method for removing thallium from thallium-containing wastewater using the liquid composite thallium remover. The present invention has a convenient thallium removal process for thallium-containing desulfurization wastewater, good stability in thallium removal effect, low cost, and the raw materials used are all environmentally friendly agents, which will not cause secondary pollution and are suitable for treating large-scale thallium-containing wastewater.

Description

Technical Field

[0001] The present application belongs to the technical field of wastewater treatment, and specifically relates to a liquid composite thallium removal agent and a preparation method and application thereof. Background Art

[0002] Thallium is a highly toxic dispersed metal. Its toxicity is much higher than that of heavy metal ions such as arsenic, cadmium, and lead under equal conditions, and is second only to methylmercury. Because thallium has a strong affinity for sulfur, it is usually associated with sulfur-containing minerals such as sphalerite, pyrite, and high-sulfur coal. In industrial production processes such as sintering of mineral materials and thermal power generation, thallium often enters the desulfurization system with sulfur-containing smoke and dust, and is eventually enriched in the desulfurization wastewater, forming high-concentration thallium-containing desulfurization wastewater. If this type of wastewater is directly discharged without effective thallium removal treatment, it will cause serious pollution to surface water, groundwater and soil. Thallium may also enter crops through enrichment effects, threatening human life and health and ecological security.

[0003] At present, the treatment technologies for thallium-containing wastewater mainly include adsorption, oxidation coagulation and sedimentation, solvent extraction and ion exchange. Although the oxidation coagulation and sedimentation method can effectively remove thallium from wastewater and reduce it to below the trace level, its application is limited due to the high cost of reagents, complex operation, and the possibility of secondary pollution. Although the solvent extraction method and the ion exchange method have good selectivity for heavy metal ions, these two methods are not suitable for treating thallium-containing desulfurization wastewater due to the large amount of industrial desulfurization wastewater, large fluctuations in water quality and complex composition.

[0004] Adsorption has become an important direction for the treatment of thallium-containing wastewater due to its advantages such as high efficiency, economy and low secondary pollution. This method forms a chemical bond between thallium ions in water and the surface of the adsorbent material through electron transfer, thereby achieving the removal of thallium ions. At present, a variety of adsorbent materials have been studied for the treatment of thallium-containing wastewater, such as carbon materials, biomass materials and metal oxides. However, existing adsorbent materials generally have problems such as limited adsorption capacity, insufficient chemical stability, complex preparation process or high cost. These defects restrict their large-scale application in industrial wastewater treatment.

[0005] In the prior art, adsorbents are mostly in solid form, such as particles, powders or supported materials. In practical applications, such solid adsorbents have problems such as difficulty in addition, uneven dispersion, and reduced adsorption efficiency. Especially in the complex and changeable water quality environment of thallium-containing desulfurization wastewater, it is difficult to meet the needs of large-scale industrial treatment. In contrast, liquid adsorbents have unique advantages: they are more dispersible and can fully contact with wastewater, significantly improving adsorption efficiency; the liquid form is convenient for precise addition through pumping equipment, and the operation is simpler; at the same time, the preparation process of liquid adsorbents can avoid the high-temperature calcination or post-treatment steps involved in traditional solid adsorbents, which helps to reduce preparation costs and reduce resource consumption.

[0006] However, the current research and application of liquid adsorbents is still in the initial exploration stage. The existing technology still lacks the development and application methods of liquid adsorbents in the treatment of thallium-containing wastewater, especially in terms of improving adsorption efficiency, enhancing chemical stability and reducing secondary pollution. Summary of the invention

[0007] Based on the needs and existing gaps in the above-mentioned fields, the present invention has developed a liquid adsorbent with high adsorption capacity, strong stability and easy addition, which not only makes up for the shortcomings of existing solid adsorbents, but also provides a new solution for the efficient treatment of thallium-containing desulfurization wastewater.

[0008] The specific technical solutions are as follows:

[0009] The first aspect of the present invention provides a liquid composite thallium removal agent, characterized in that a soluble titanium salt and dilute sulfuric acid are mixed to obtain a first mixed solution, and then an adsorption carrier and a titanium salt dispersed catalyst are added to the first mixed solution to obtain a second mixed solution; the second mixed solution is heated to boiling, then reflux cooled, and the pH is adjusted to weak alkalinity.

[0010] Preferably, the liquid composite thallium removal agent is characterized in that the soluble titanium salt is selected from a combination of one or more of titanium sulfate, titanyl sulfate, titanium tetrachloride and titanium tetrabromide;

[0011] The titanium salt dispersed catalyst is ethylene glycol monomethyl ether;

[0012] The adsorption carrier is 50-200 mesh activated carbon.

[0013] Preferably, the liquid composite thallium removal agent is characterized in that the weight ratio of soluble titanium salt to dilute sulfuric acid is 10~30:100~5000; the concentration of dilute sulfuric acid is 1 mmol / L~500 mmol / L; and the weak alkalinity refers to a pH of 7~9.

[0014] Preferably, any of the above-mentioned liquid composite thallium removal agents is characterized in that the weight ratio of the adsorption carrier, the titanium salt dispersed catalyst and the first mixed solution is 5~20: 3~10: 250~1500.

[0015] Another aspect of the present invention provides a method for preparing any of the above-mentioned liquid composite thallium removal agents, characterized in that it comprises the following steps:

[0016] 1) uniformly mixing a soluble titanium salt and dilute sulfuric acid to obtain the first mixed solution;

[0017] 2) adding an adsorption carrier and a titanium salt dispersed catalyst to the first mixed solution, stirring evenly, to prepare a second mixed solution;

[0018] 3) The second mixed solution is heated to boiling, refluxed and cooled, and the pH of the solution is adjusted to weak alkalinity to obtain the liquid composite thallium removal agent.

[0019] Preferably, the preparation method is characterized in that the reflux treatment time is 0.5 to 2 hours; and the pH value is adjusted using one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate.

[0020] In another aspect of the present invention, a process for removing thallium from thallium-containing desulfurization wastewater is provided, characterized in that the process is as follows: Figure 1 As shown, the following steps are included:

[0021] S1. The pH of the thallium desulfurization wastewater to be treated is adjusted to 6-9 to obtain adjusted wastewater;

[0022] S2. Adding any of the above-mentioned liquid composite thallium removal agents to the wastewater under the condition of stirring;

[0023] S3. Add coagulant and flocculant to the wastewater after the reaction is completed, let it stand for precipitation after mixed reaction, separate the solid and liquid, and discharge the supernatant liquid to achieve thallium removal from the wastewater.

[0024] Preferably, the thallium removal process is characterized in that the thallium content in the wastewater is 100 μg / L ~ 5 mg / L; and the pH value is adjusted by using a combination of one or more of sulfuric acid, liquid alkali, and lime milk.

[0025] Preferably, the thallium removal process is characterized in that the amount of the liquid composite thallium removal agent added is 0.3% to 1% of the volume of the regulated wastewater; the specific amount added can be adjusted according to the concentration of thallium ions in the wastewater and the water quality conditions to achieve the best adsorption effect;

[0026] The reaction time under stirring conditions in S2 is 0.5 to 2 hours; in S3, the mixing reaction time is 0.2 to 2 hours, and the static precipitation time is 15 to 45 minutes.

[0027] Preferably, the thallium removal process is characterized in that the coagulant is a mixture of 5 to 10 parts by weight of polyaluminium chloride, 3 to 6 parts by weight of 100 mesh activated carbon, and 3,000 to 10,000 parts by weight of water; the amount of the coagulant added accounts for 0.08% to 0.15% of the volume of the regulated wastewater;

[0028] The flocculant is prepared by mixing 5-10 parts by weight of polyacrylamide and 3000-6000 parts by weight of water; the amount of the flocculant added is 0.05% to 0.08% of the volume of the regulated wastewater.

[0029] The present invention takes into account that thallium in wastewater mainly exists in the form of Tl⁺. The core component of the liquid composite thallium remover is active titanium dioxide, which has a large specific surface area and abundant adsorption sites. Under alkaline conditions, active titanium dioxide efficiently removes Tl⁺ from wastewater through surface chemical adsorption. Unlike traditional solid adsorbents, liquid composite thallium removers have higher dispersibility and more complete contact with wastewater, which not only significantly improves the adsorption efficiency, but also greatly simplifies the operation process, and is particularly suitable for the continuous treatment needs of industrial wastewater.

[0030] In the coagulation and flocculation stages, the aggregation ability of particles is first enhanced by coagulants, and then the active titanium dioxide adsorbed with Tl⁺ and suspended particles are aggregated into larger flocs through the adsorption bridging and net capture and sweeping effects of flocculants. This synergistic effect effectively improves the sedimentation performance, making the solid-liquid separation process more efficient, and the treated supernatant is stably discharged to the standard.

[0031] This application has at least the following beneficial technical effects:

[0032] The present application provides a liquid composite thallium remover and its supporting thallium removal process for thallium-containing desulfurization wastewater. Compared with traditional solid adsorbents, liquid composite thallium removers have higher dispersibility and can be accurately added through a peristaltic pump or a metering pump, fully contacting with wastewater, and significantly improving adsorption efficiency; its preparation adopts a heating reflux method, and the raw materials, catalysts and carriers are fully mixed through homogenization operations to generate active titanium dioxide adsorbents with uniform particle size, stable dispersion, and not easy to agglomerate. The adsorption performance is significantly improved, and it can adapt to the complex and volatile water quality conditions of sulfur-containing desulfurization wastewater. The liquid form simplifies the addition process and process flow, and is more suitable for the continuous treatment of industrial wastewater.

[0033] The preparation method of the liquid composite thallium removal agent of the present application is simple, and the raw materials are selected from soluble titanium salts, dilute sulfuric acid and environmentally friendly additives, which are low-cost and green. Active titanium dioxide is generated by hydrolysis of titanium salts, which significantly improves the adsorption capacity and chemical stability of thallium ions, ensuring long-term and reliable thallium removal effects. The process avoids the complex drying, calcination and washing steps of traditional solid adsorbents, does not produce secondary pollution, has high preparation efficiency, and is easy to promote industrialization. The sludge generated after treatment is easy to dispose of later, and the overall process is environmentally friendly and efficient.

[0034] The thallium removal process for thallium-containing desulfurization wastewater of the present application has the characteristics of simple process, stable effect and low cost. After adjusting the pH of the wastewater, liquid composite thallium removal agent and flocculant are added, and the efficient removal of thallium ions can be achieved through mixing, reaction and precipitation separation. The process requires fewer types of reagents and fewer operating steps, and the treated supernatant can be directly discharged to meet the standards, meeting the large-scale treatment needs of thallium-containing wastewater, and is particularly suitable for industrial wastewater environments with complex water quality and variable components. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for removing thallium from thallium-containing desulfurization wastewater in the present application;

[0036] Figure 2 This is the scanning electron microscope photo and EDS spectrum of No. 1 liquid composite thallium remover;

[0037] Among them, (a), (b) and (c) are scanning electron microscope photos of liquid composite thallium remover No. 1; (d) is the EDS spectrum of liquid composite thallium remover No. 1;

[0038] Figure 3 This is the scanning electron microscope photo and EDS spectrum of No. 2 liquid composite thallium remover;

[0039] Among them, (a), (b) and (c) are scanning electron microscope photos of liquid composite thallium remover No. 2; (d) is the EDS spectrum of liquid composite thallium remover No. 2;

[0040] Figure 4 This is the scanning electron microscope photo and EDS spectrum of No. 3 liquid composite thallium remover;

[0041] Among them, (a), (b) and (c) are scanning electron microscope photos of No. 3 liquid composite thallium removal; (d) is the EDS spectrum of No. 3 liquid composite thallium removal;

[0042] Figure 5 1, 2 and 3 are the particle size distribution diagrams of the liquid composite thallium removal agents in the examples. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is exemplarily described below through specific embodiments, and these embodiments should not be regarded as limiting the protection scope of the present invention.

[0044] Example 1. Liquid composite thallium removal agent of the present invention and preparation method thereof

[0045] The application discloses a liquid composite thallium removal agent, which is a first mixed solution obtained by mixing a soluble titanium salt with dilute sulfuric acid, and then adding an adsorption carrier and a titanium salt dispersion catalyst to the first mixed solution to obtain a second mixed solution; the second mixed solution is heated to boiling, then refluxed and cooled, and the pH is adjusted to weak alkalinity to obtain the second mixed solution.

[0046] Specifically prepared by the following steps:

[0047] S1. Weigh 10 to 30 parts by weight of a soluble titanium salt and slowly add it to 100 to 5000 parts by weight of dilute sulfuric acid, while maintaining uniform stirring to ensure that the titanium salt is fully dissolved and evenly dispersed to avoid crystallization or uneven hydrolysis caused by excessive local concentration. After mixing, continue stirring for 10 to 20 minutes until the solution is completely clear without precipitation or suspended particles. Finally, a first mixed solution is obtained.

[0048] The soluble titanium salt may be one or more of titanium sulfate, titanyl sulfate, titanium tetrachloride and titanium tetrabromide. The concentration of the dilute sulfuric acid ranges from 1 mmol / L to 500 mmol / L.

[0049] S2. Take 250 to 1500 parts by weight of the first mixed solution, add 5 to 20 parts by weight of the adsorption carrier and 3 to 10 parts by weight of the titanium salt dispersed catalyst in sequence, stir evenly, and prepare a second mixed solution.

[0050] S3. The second mixed solution is heated to boiling and refluxed until cooled, and then the first acid-base regulator is added to adjust the pH of the solution to 7-9, thereby obtaining a liquid composite thallium removal agent.

[0051] Specifically, in this embodiment, the adsorption carrier is activated carbon with a mesh size of 50 to 200, the first acid-base regulator can be one or more combinations of sodium hydroxide, sodium carbonate and sodium bicarbonate, and the reflux time is 0.5 to 2 hours.

[0052] The advantage of this step is that by adding the adsorption carrier and the catalyst to the first mixed solution and combining the heating reflux process, the titanium salt is uniformly hydrolyzed to generate active titanium dioxide, which exists stably in liquid form. The liquid adsorbent has excellent dispersibility and can be evenly loaded on the surface of the activated carbon, ensuring high adsorption efficiency and adaptability to different wastewater quality conditions.

[0053] Example 2. Effects of different catalysts on the performance of liquid composite thallium removal agent

[0054] Weigh 30 parts by weight of titanium sulfate and 30 parts by weight of titanyl sulfate, dissolve them in 3000 parts by weight of dilute sulfuric acid with a concentration of 0.3 mol / L, and stir them thoroughly until they are completely dissolved. Then, add 45 parts by weight of activated carbon with a particle size of 100 mesh, and continue to stir to make it evenly dispersed. The resulting solution is divided into three equal parts, named first mixed solution I, first mixed solution II, and first mixed solution III, respectively.

[0055] In the first mixed solution I, 5 parts by weight of ethylene glycol monomethyl ether was added as a catalyst, stirred evenly, heated to boiling, and kept under reflux for 1 hour. After the solution was cooled, sodium bicarbonate was added to adjust the pH to 8.5, and finally a No. 1 liquid composite thallium removal agent was obtained.

[0056] In the first mixed solution II, 5 parts by weight of acetic acid was added as a catalyst, and the same operating conditions as those of the mixed solution I were adopted. After being stirred evenly, the mixture was heated to boiling and kept under reflux for 1 hour. After the solution was cooled, sodium bicarbonate was added to adjust the pH to 8.5, and finally a liquid composite thallium removal agent No. 2 was obtained.

[0057] The first mixed solution III was used as a control group without adding any catalyst. The mixed solution was stirred evenly and heated to boiling under the same operating conditions as the mixed solutions I and II, and kept under reflux for 1 hour. After the solution was cooled, sodium bicarbonate was added to adjust the pH to 8.5, and finally a liquid composite thallium removal agent No. 3 was obtained.

[0058] In order to analyze the microscopic morphology and particle size distribution of each liquid composite thallium remover, a small amount of liquid composite thallium remover No. 1, liquid composite thallium remover No. 2 and liquid composite thallium remover No. 3 were taken, filtered, washed with pure water and dried. The dried samples were characterized using a scanning electron microscope (SEM) and a Malvern laser particle size analyzer to evaluate the dispersibility, particle size distribution and specific surface area of ​​the particles.

[0059] like Figure 2-Figure 5 As shown, the morphology and particle size distribution of liquid composite thallium remover No. 1, liquid composite thallium remover No. 2 and liquid composite thallium remover No. 3 show significant differences.

[0060] like Figure 2 As shown in the figure, liquid composite thallium remover No. 1 exhibits the best particle size and dispersibility, with a particle size concentrated between 1 and 5 μm, significant particle uniformity, and no obvious agglomeration. The SEM image clearly shows the advantages of particle dispersibility and specific surface area. The results of energy spectrum analysis (EDS) show that titanium dioxide is fully generated and the ratio of titanium to oxygen meets the design expectations. High dispersibility and uniformity make liquid composite thallium remover No. 1 have a large specific surface area and abundant adsorption sites, making it an ideal material for efficient adsorption of thallium ions.

[0061] like Figure 3 As shown in the figure, the particle size range of liquid composite thallium remover No. 2 is relatively wide, mainly distributed between 20-40 μm, and the uniformity of the particles is inferior to that of liquid composite thallium remover No. 1. SEM images show that the surface of some particles is smooth, but there is a certain degree of agglomeration, and the particle size distribution deviation is large, which may lead to a decrease in specific surface area. Energy spectrum analysis shows that the distribution of titanium and oxygen is more uneven than that of liquid composite thallium remover No. 1. Although acetic acid can partially regulate the hydrolysis process of titanium salts, its effect is far less significant than that of ethylene glycol monomethyl ether, resulting in a high degree of particle agglomeration and limited performance.

[0062] like Figure 4As shown in the figure, liquid composite thallium remover No. 3 performed the worst, with the widest particle size distribution, a large number of particles exceeding 50 μm, and serious agglomeration. SEM images show that its particles are irregular in shape, rough on the surface, and even form large agglomerates. EDS analysis results show that the content of titanium and oxygen is significantly low, indicating that titanium dioxide is not fully generated and the adsorption performance of the particles is much lower than that of liquid composite thallium removers No. 1 and No. 2.

[0063] like Figure 5 As shown, in order to further verify the above results: Liquid composite thallium remover No. 1 has the most concentrated particle size distribution and the best particle uniformity; Liquid composite thallium remover No. 2 has a wide distribution range and medium uniformity; Liquid composite thallium remover No. 3 has the widest particle distribution, significant agglomeration phenomenon and the worst performance.

[0064] The experimental results show that ethylene glycol monomethyl ether plays a more obvious dispersing role in the hydrolysis process of soluble titanium salt, which helps the titanium salt to dissolve evenly and generate titanium dioxide particles with concentrated particle size distribution, thereby significantly improving the performance of liquid composite thallium remover No. 1. In contrast, acetic acid has a limited effect, and liquid composite thallium remover No. 3 without a catalyst shows a clear disadvantage due to the uncontrolled hydrolysis process.

[0065] Example 3 Treatment of Thallium-Containing Wastewater Using the Liquid Composite Thallium Removal Agent of the Present Invention

[0066] Preparation of liquid composite thallium removal agent, in this embodiment, 10 parts by weight of titanium sulfate and 10 parts by weight of titanyl sulfate are dissolved in 1000 parts by weight of dilute sulfuric acid with a concentration of 0.3 mol / L, and after fully dissolved, 15 parts by weight of 100 mesh activated carbon and 5 parts by weight of ethylene glycol monomethyl ether are added and stirred evenly. The mixed solution is heated to boiling and refluxed for 1 hour, and sodium bicarbonate is added after cooling, and the pH of the solution is adjusted to 8.5 to prepare a liquid composite thallium removal agent.

[0067] Wastewater treatment steps:

[0068] S1. Take 10,000 parts by weight of thallium-containing desulfurization wastewater (the initial pH of the test is 6.3, and the total thallium content is 277 μg / L), add liquid alkali to adjust the pH of the wastewater to 8, and generate regulated wastewater suitable for thallium ion adsorption.

[0069] S2. Add 80 parts by weight of the liquid composite thallium removal agent to the adjusted wastewater, stir evenly and react for 45 minutes to allow the active titanium dioxide to fully adsorb the thallium ions in the wastewater.

[0070] S3. Add 10 parts by weight of a coagulant (mixed with 5 parts by weight of polyaluminium chloride, 10 parts by weight of 100-mesh activated carbon and 10,000 parts by weight of water) and 6 parts by weight of a flocculant (mixed with 10 parts by weight of anionic polyacrylamide and 6,000 parts by weight of water) to the wastewater after the reaction, stir and react for 0.5 hour, let it stand and settle for 40 minutes, complete solid-liquid separation, and discharge the supernatant.

[0071] After testing, the thallium concentration in the treated wastewater (supernatant) dropped to 1.34 μg / L, and the thallium removal rate exceeded 99%, meeting the wastewater discharge standards and complying with environmental protection requirements.

[0072] Example 4 Treatment of Thallium-Containing Wastewater Using the Liquid Composite Thallium Removal Agent of the Present Invention

[0073] In this embodiment, the preparation of the liquid composite thallium remover is as follows: 15 parts by weight of titanium sulfate and 5 parts by weight of titanium tetrachloride are dissolved in 1500 parts by weight of dilute sulfuric acid with a concentration of 0.5 mol / L, and after sufficient dissolution, 10 parts by weight of 100 mesh activated carbon and 8 parts by weight of ethylene glycol monomethyl ether are added and stirred evenly; the mixed solution is heated to boiling and refluxed for 1 hour, and after cooling, sodium bicarbonate and sodium hydroxide are added to gradually adjust the pH of the solution to 8 to prepare a liquid composite thallium remover.

[0074] Wastewater treatment steps:

[0075] S1. Take 10,000 parts by weight of thallium-containing desulfurization wastewater (initial pH is 6.6, total thallium content is 412 μg / L), adjust the pH of the wastewater to 8.5 by adding NaOH and lime milk, and generate regulated wastewater suitable for thallium ion adsorption.

[0076] S2. Add 100 parts by weight of a liquid composite thallium removal agent to the regulated wastewater, stir evenly and react for 30 minutes to allow the active titanium dioxide to fully adsorb thallium ions in the wastewater.

[0077] S3. Add 8 parts by weight of coagulant (mixed with 5 parts by weight of polyaluminium chloride, 6 parts by weight of 100 mesh activated carbon and 10,000 parts by weight of water) and 6 parts by weight of flocculant (mixed with 5 parts by weight of polyacrylamide and 5,000 parts by weight of water) to the wastewater after the reaction, stir and react for 1 hour, let it stand for 45 minutes, complete the solid-liquid separation, and discharge the supernatant. After testing, the thallium concentration in the treated wastewater (supernatant) dropped to 0.93 μg / L, and the thallium removal rate exceeded 99%, meeting the wastewater discharge standard and meeting environmental protection requirements.

[0078] Example 5 Treatment of Thallium-Containing Wastewater Using the Liquid Composite Thallium Removal Agent of the Present Invention

[0079] Preparation of liquid composite thallium removal agent, in this embodiment, 15 parts by weight of titanium sulfate and 5 parts by weight of titanium tetrachloride are dissolved in 1500 parts by weight of dilute sulfuric acid with a concentration of 0.5 mol / L, and after fully dissolved, 10 parts by weight of 100 mesh activated carbon and 8 parts by weight of ethylene glycol monomethyl ether are added and stirred evenly. The mixed solution is heated to boiling and refluxed for 1 hour, and sodium bicarbonate and sodium hydroxide are added after cooling, and the pH of the solution is gradually adjusted to 8 to prepare a liquid composite thallium removal agent.

[0080] Wastewater treatment steps:

[0081] S1. Take 10,000 parts by weight of thallium-containing desulfurization wastewater (initial pH is 6.6, total thallium content is 412 μg / L), adjust the pH of the wastewater to 8.5 by adding NaOH and lime milk, and generate regulated wastewater suitable for thallium ion adsorption.

[0082] S2. Add 100 parts by weight of a liquid composite thallium removal agent to the regulated wastewater, stir evenly and react for 30 minutes to allow the active titanium dioxide to fully adsorb thallium ions in the wastewater.

[0083] S3. Add 8 parts by weight of coagulant (mixed with 10 parts by weight of polyaluminium chloride (PAC), 5 parts by weight of 100 mesh activated carbon and 6000 parts by weight of water) and 6 parts by weight of flocculant (mixed with 6 parts by weight of anionic polyacrylamide (PAM) and 3000 parts by weight of water) to the wastewater after the reaction. After stirring evenly and reacting for 1 hour, let it stand for 45 minutes to complete solid-liquid separation, and discharge the supernatant.

[0084] After testing, the thallium concentration in the treated wastewater (supernatant) dropped to 0.93 μg / L, and the thallium removal rate exceeded 99%, meeting the wastewater discharge standards and complying with environmental protection requirements.

[0085] Example 6 Treatment of Thallium-Containing Wastewater Using the Liquid Composite Thallium Removal Agent of the Present Invention

[0086] Preparation of liquid composite thallium removal agent, in this embodiment, 10 parts by weight of titanium sulfate, 5 parts by weight of titanyl sulfate and 5 parts by weight of titanium tetrachloride are dissolved in 1000 parts by weight of dilute sulfuric acid with a concentration of 0.3 mol / L, and after fully dissolved, 15 parts by weight of 100 mesh activated carbon and 5 parts by weight of ethylene glycol monomethyl ether are added and stirred evenly. The mixed solution is heated to boiling and refluxed for 1.5 hours, and after cooling, sodium bicarbonate and sodium hydroxide are added to gradually adjust the pH of the solution to 9 to prepare a liquid composite thallium removal agent.

[0087] Wastewater treatment steps:

[0088] S1. Take 10,000 parts by weight of thallium-containing desulfurization wastewater (initial pH is 6.0, total thallium content is 375 μg / L), adjust the pH of the wastewater to 8.8 by adding NaOH, and generate regulated wastewater suitable for thallium ion adsorption.

[0089] S2. Add 90 parts by weight of a liquid composite thallium removal agent to the regulated wastewater, stir evenly and react for 40 minutes to allow the active titanium dioxide to fully adsorb thallium ions in the wastewater.

[0090] S3. Add 7 parts by weight of coagulant (mixed with 15 parts by weight of polyaluminium chloride, 8 parts by weight of 100 mesh activated carbon and 6000 parts by weight of water) and 10 parts by weight of flocculant (mixed with 5 parts by weight of anionic polyacrylamide (PAM) and 3000 parts by weight of water) to the wastewater after the reaction; after stirring and mixing and reacting for 0.5 hour, let it stand and settle for 30 minutes to complete solid-liquid separation, and discharge the supernatant.

[0091] After testing, the thallium concentration in the treated wastewater (supernatant) dropped to 1.89 μg / L, and the thallium removal rate exceeded 99%, meeting the wastewater discharge standards and complying with environmental protection requirements.

[0092] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a liquid composite thallium removal agent, characterized in that: The following steps are involved: 1) uniformly mixing a soluble titanium salt and dilute sulfuric acid to obtain a first mixed solution; 2) adding an adsorption carrier and a titanium salt dispersion catalyst to the first mixed solution, stirring evenly, to prepare a second mixed solution, wherein the titanium salt dispersion catalyst is ethylene glycol monomethyl ether; 3) heating the second mixed solution to boiling, refluxing and cooling, and adjusting the pH of the solution to 7-9 to obtain the liquid composite thallium removal agent; The weight ratio of the soluble titanium salt to the dilute sulfuric acid is 10-30:100-5000; the concentration of the dilute sulfuric acid is 1 mmol / L-500 mmol / L; and the adsorption carrier is activated carbon.

2. The method according to claim 1, characterized in that The soluble titanium salt is selected from one or more of titanium sulfate, titanyl sulfate, titanium tetrachloride and titanium tetrabromide; and the activated carbon is 50-200 mesh activated carbon.

3. The method according to claim 1 or 2, characterized in that: The weight ratio of the adsorption carrier, the titanium salt dispersed catalyst and the first mixed solution is 5-20:3-10:250-1500.

4. The method according to claim 3, characterized in that The reflux treatment time is 0.5 to 2 hours; the solution pH is adjusted to 7-9, using one or more of sodium hydroxide, sodium carbonate and sodium bicarbonate.

5. A liquid composite thallium removing agent prepared by the method described in any one of claims 1 to 4.

6. A process for removing thallium from thallium-containing desulfurization wastewater, characterized in that: The following steps are involved: S1. The pH of the thallium desulfurization wastewater to be treated is adjusted to 6-9 to obtain adjusted wastewater; S2. Adding the liquid composite thallium removal agent according to claim 5 to the wastewater in the adjustment, reacting under stirring conditions; S3. Add coagulant and flocculant to the wastewater after the reaction is completed, let it stand for precipitation after mixed reaction, separate the solid and liquid, and discharge the upper clear liquid to achieve thallium removal from the wastewater.

7. The thallium removal process according to claim 6, characterized in that: The thallium content in the wastewater is 100 μg / L~5 mg / L; In step S1, pH adjustment is performed by using a combination of one or more of sulfuric acid and liquid alkali.

8. The thallium removal process according to claim 6, characterized in that: In step S2, the amount of the liquid composite thallium removal agent added is 0.3% to 1% of the volume of the regulated wastewater; In step S2, the reaction time is 0.5 to 2 hours under stirring; In step S3, the mixing reaction time is 0.2 to 2 hours, and the static precipitation time is 15 to 45 minutes.

9. The thallium removal process according to claim 6, characterized in that: The coagulant is a mixture of 5-10 parts by weight of polyaluminium chloride, 3-6 parts by weight of 100 mesh activated carbon and 3000-10000 parts by weight of water; the amount of the coagulant added is 0.08% to 0.15% of the volume of the regulated wastewater; The flocculant is prepared by mixing 5-10 parts by weight of polyacrylamide and 3000-6000 parts by weight of water; the added amount of the flocculant accounts for 0.05% to 0.08% of the volume of the regulated wastewater.

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