A safe treatment method for decommissioning perchloric acid

Abstract

The present application relates to the technical field of hazardous waste treatment, and more particularly to a safe treatment method of discarded perchloric acid, comprising the following steps: step one, taking a certain amount of water, slowly adding perchloric acid to it to obtain pretreatment liquid A, reducing the danger and oxidizing property of the pretreated perchloric acid; step two, slowly adding sodium hydroxide solution to the pretreatment liquid A to neutralize the perchloric acid, so that sodium perchlorate is generated, obtaining mixed liquid B, and reducing the danger of high corrosiveness of the perchloric acid. In the present application, a safe treatment method of discarded perchloric acid is provided, which is a safe and stable treatment method for discarded perchloric acid. By controlling the reagent of the reaction system, the safe treatment of perchloric acid is realized through a multi-stage reaction process. The three wastes of the system are effectively collected and treated throughout the reaction process, so as to achieve a treatment method for safely operating the environment when disposing of perchloric acid.

Description

Technical Field

[0001] This invention relates to the field of hazardous waste treatment technology, and in particular to a safe treatment method for waste perchloric acid. Background Technology

[0002] Perchloric acid is an inorganic compound with the chemical formula HClO4. It is the strongest of the six major inorganic acids and is the hydrate of the highest-valence oxide of chlorine. It is a colorless, transparent, fuming liquid. Perchloric acid is the strongest of the inorganic oxyacids. It supports combustion, is highly corrosive and irritating, and can cause burns to humans. Industrially, it is used in the preparation of perchlorates, the purification of synthetic diamonds, the manufacture of photographic film, the pharmaceutical industry, the electropolishing industry, the production of grinding wheels, the removal of carbon particles, and as an oxidizing agent. Perchloric acid also has many applications in the laboratory. It is commonly used as an oxidizing agent to oxidize metals, organic compounds, and to evaluate the oxidizing properties of substances. In analytical chemistry, perchloric acid can be used as an acid for sample treatment, widely used in sample pretreatment, digestion, and dissolution. Therefore, universities and laboratories generate large quantities of waste perchloric acid, which poses a significant hazard.

[0003] After being released, perchloric acid readily forms perchlorate with alkaline substances, due to the presence of ClO4. － Perchloric acid possesses toxicological characteristics that interfere with iodine absorption in the human body and inhibit the thyroid gland's ability to regulate hormone secretion and metabolism. It may also cause some degree of damage to red blood cells and liver and kidneys, leading to significant environmental pollution and human health and safety concerns that have drawn considerable attention from researchers. Effective removal of perchloric acid based on a thorough understanding of its environmental chemical properties and hazards has been a key research focus and challenge in recent years. Furthermore, the high reactivity of perchloric acid makes its treatment difficult, posing significant safety hazards and severely impacting the ecological environment and human health. Currently, there are no readily available treatment methods. Therefore, this study investigated a dilution pretreatment and multi-stage reaction process to treat this hazardous waste. Summary of the Invention

[0004] The purpose of this invention is to provide a safe method for treating waste perchloric acid in order to solve the problems existing in the prior art described above.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A safe method for disposing of waste perchloric acid includes the following steps:

[0007] Step 1: Take a certain amount of water and slowly add perchloric acid to it to obtain pretreatment solution A. Pretreatment of perchloric acid reduces its danger and oxidizing properties.

[0008] Step 2: Slowly add sodium hydroxide solution to pretreatment solution A to neutralize perchloric acid and generate sodium perchlorate, thus obtaining mixture B and reducing the risk of highly corrosive perchloric acid.

[0009] Step 3: Add titanium trichloride waste liquid to mixture B, stir for a period of time, then add alanine solution dropwise to catalyze the reaction and obtain mixture C. Finally, heat mixture C.

[0010] Step 4: After the reaction is complete, slowly add sodium hydroxide solution to mixture C to adjust the pH to 8.0-9.0, thus obtaining mixture D;

[0011] Step 5, and the reactions in steps 1 through 4, are all carried out in a fume hood;

[0012] Step 6: After the mixed liquid is filtered by plate and frame filter press D, the filtrate is reused after evaporation, desalination and biochemical treatment, and the filter residue is collected for resource utilization.

[0013] As a further description of the above technical solution:

[0014] In step one, the ratio of recycled water to perchloric acid is 10:1, and the perchloric acid is slowly added dropwise to the water.

[0015] As a further description of the above technical solution:

[0016] When the concentration of sodium hydroxide in step two is 15%-20% and the pH of the reaction solution is 7.0-8.0, the addition of sodium hydroxide solution should be stopped.

[0017] As a further description of the above technical solution:

[0018] The titanium trichloride waste liquid in step three is a titanium trichloride solution generated during the determination of total iron content in iron ore. The titanium trichloride content is 15%. 1%-5% hydrochloric acid is added to the titanium trichloride solution to ensure that the titanium trichloride solution is acidic.

[0019] As a further description of the above technical solution:

[0020] In step three, the concentration of alanine solution is 30%-40%, and the reaction temperature is controlled at 50-60℃.

[0021] As a further description of the above technical solution:

[0022] The filter residue produced in step five is titanium dioxide, which can be utilized as a resource. The waste liquid produces sodium chloride as a byproduct after evaporation. The resulting evaporation filtrate meets the requirements for reuse after biochemical treatment.

[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. In this invention, the goal of treating waste with waste is achieved by utilizing the effective components in hazardous waste.

[0025] 2. In this invention, perchlorate is highly stable and its structure is extremely difficult to destroy with general reducing agents. Heating to destroy it requires a temperature of 100°C or even higher. This invention uses titanium trichloride waste liquid and alanine catalyst to reduce perchlorate to chloride ions at 50°C, and finally prepare sodium chloride by resource utilization.

[0026] 3. In this invention, the filter residue generated during the treatment of perchloric acid is titanium dioxide, the by-product is sodium chloride, and the biochemical effluent can be used as recycled water for perchloric acid pretreatment. This not only treats perchloric acid but also produces titanium dioxide and sodium chloride, turning waste into treasure.

[0027] 4. In this invention, the waste titanium trichloride solution and the catalyst alanine used in the disposal process are inexpensive and readily available, which greatly reduces the processing cost. Attached Figure Description

[0028] Figure 1 This is a comparison table of perchlorate ion detection data for four specific embodiments of the present invention. Detailed Implementation

[0029] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1 This invention provides a technical solution: a safe treatment method for waste perchloric acid, comprising the following steps:

[0031] Step 1: Take a certain amount of water and slowly add perchloric acid to it to obtain pretreatment solution A. Pretreatment of perchloric acid reduces its danger and oxidizing properties. In step 1, the ratio of recycled water to perchloric acid is 10:1. Perchloric acid is slowly added to the water.

[0032] The second step is to slowly add a 15%-20% sodium hydroxide solution to the pretreatment solution A to neutralize the perchloric acid and generate sodium perchlorate, thus obtaining a mixed solution B. This reduces the risk of high corrosiveness of perchloric acid. When the pH of the reaction solution is 7.0-8.0, the addition of sodium hydroxide solution is stopped.

[0033] The third step involves adding titanium trichloride waste liquid to mixture B, stirring for a period of time, and then adding a 30%-40% alanine solution to catalyze the reaction, resulting in mixture C. Finally, mixture C is heated, with the reaction temperature controlled at 50-60℃. In this step, the titanium trichloride waste liquid is a titanium trichloride solution produced during the determination of total iron content in iron ore, with a titanium trichloride content of 15%. 1%-5% hydrochloric acid is added to the titanium trichloride solution to ensure that the titanium trichloride solution is acidic.

[0034] Step 4: After the reaction is complete, slowly add sodium hydroxide solution to mixture C to adjust the pH to 8.0-9.0, thus obtaining mixture D;

[0035] Step 5, and all reactions from steps 1 to 4, are carried out in a fume hood;

[0036] Step 6: After the mixed liquid is filtered by plate and frame filter press D, the filtrate is evaporated, desalinated, and biochemically treated before being reused. The filter residue is collected for resource utilization. The filter residue produced in this step is titanium dioxide, which can be utilized as a resource. The waste liquid produces sodium chloride as a byproduct after evaporation. The evaporated filtrate meets the reuse requirements after biochemical treatment.

[0037] Specifically, this invention effectively utilizes the effective components in hazardous waste to achieve the goal of treating waste with waste, and the liquid and solid components generated during the treatment process are effectively disposed of and recycled, resulting in significant economic and environmental benefits.

[0038] In this invention, titanium trichloride waste liquid exhibits strong reducing properties, capable of slowly reducing perchlorate and effectively treating perchloric acid. Ultraviolet absorption spectroscopy reveals an absorption peak at 480 nm for the titanium trichloride solution, indicating that titanium trichloride exists in solution in the form (HO)Ti(OH)₂₅. 2+ The mechanism of sodium perchlorate reduction is as follows:

[0039] 8(HO)Ti(OH2)5 2+ +ClO 4- =8TiO2+Cl - +16H + +36H2O

[0040] Furthermore, this invention utilizes alanine as a catalyst, which not only improves the catalytic reaction efficiency but also broadens the applicable range. Without the addition of alanine, the optimal pH for the reduction of perchlorate by titanium trichloride is 2.0. The reduction rate significantly increases when the pH ranges from 1.2 to 2.0. At pH values ​​> 2.0, titanium dioxide precipitates form, and the reduction is significantly inhibited. When alanine is added, sodium perchlorate can be reduced even at near-neutral pH. The presence of alanine significantly improves the reduction efficiency of perchlorate because alanine forms a complex with Ti(III), reducing titanium dioxide precipitation within the pH range of 2.0 to 5.0 and greatly increasing the [Ti(III)] content in the solution, further enhancing the reduction efficiency of perchlorate.

[0041] The solution of the present invention will be further described in detail below with reference to implementation examples.

[0042] The test sample was expired perchloric acid, a chemical reagent received by a hazardous waste company.

[0043] Implementation Case 1

[0044] Add 10 mL of perchloric acid to 100 mL of water, stir thoroughly, and mix well. Then, add 15% sodium hydroxide solution to the mixture, controlling the pH to 7.0 before stopping the addition. Next, slowly add 200 mL of expired waste titanium trichloride solution (from the determination of total iron content in iron ore), 10 mL of 1% hydrochloric acid, and then 50 mL of 30% alanine solution. Stir thoroughly and heat in an oil bath to 50°C for 3 hours. Then, add 15% sodium hydroxide solution to adjust the pH to 9.0, and filter to obtain titanium dioxide residue. The filtrate is evaporated to produce sodium chloride as a byproduct. The perchlorate content of the filtrate after evaporation is determined according to GB 5009.291-2023.

[0045] Implementation Case 2

[0046] Add 100 mL of perchloric acid to 1000 mL of water, stir thoroughly, and mix well. Then add 15% sodium hydroxide solution to the mixture, controlling the pH to 7.0 before stopping the addition. Next, slowly add 2000 mL of expired ferric chloride solution (used for determining the total iron content in iron ore), 100 mL of 1% hydrochloric acid, and then 500 mL of 30% alanine solution, stirring thoroughly. Heat to 50°C in an oil bath and react for 3 hours. Then, adjust the pH to 9.0 with 15% sodium hydroxide solution, filter, and obtain titanium dioxide residue. Evaporate the filtrate to produce sodium chloride as a byproduct. After evaporation, the perchlorate content of the filtrate is determined according to GB5009.291-2023.

[0047] Implementation Case 3

[0048] The difference from Implementation Case 1 is that 10 mL of 30% alanine solution was added, while the rest of the added amounts and proportions were the same.

[0049] Implementation Case 4

[0050] The difference from Implementation Case 1 is that 100 mL of 30% alanine solution was added, while the rest of the added amounts and proportions were the same.

[0051] In summary, please refer to Figure 1 As shown in Examples 1-2, the safe treatment method for waste perchloric acid provided by this invention has a large treatment capacity and good treatment effect. Comparing with Example 3, it can be seen that without the addition of alanine solution, the treatment effect is poor, and perchlorate is not completely removed. The addition of alanine increases the soluble Ti, forming polynuclear titanium seeds TiOTiOH. 3+ This is beneficial for the reduction of perchlorate. In contrast, in Case 4, adding an excessive amount of alanine solution resulted in a perchlorate concentration of 5 mg / L, indicating that the perchlorate reduction kinetics were hindered. Therefore, adding an excessive amount of alanine is unnecessary and detrimental.

[0052] This invention discloses a safe treatment method for waste perchloric acid. The method involves adding 15% sodium hydroxide to convert titanium ions in the waste liquid into titanium dioxide precipitate. After filtration, washing, and drying, the titanium dioxide product is obtained with a dry basis purity of 98%, meeting the requirements for industrial-grade titanium dioxide. The treated filtrate, after evaporation, produces sodium chloride as a byproduct. After recrystallization, the dry basis purity is 99%, meeting the quality standards for industrial-grade sodium chloride (greater than 98.5%). This invention utilizes the filter residue generated during the perchloric acid treatment process to produce titanium dioxide, and sodium chloride as a byproduct, thus not only treating the perchloric acid but also producing titanium dioxide and sodium chloride, turning waste into valuable resources.

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A safe method for disposing of waste perchloric acid, characterized in that, Includes the following steps: Step 1: Take a certain amount of water and slowly add perchloric acid to it to obtain pretreatment solution A. Pretreatment of perchloric acid reduces its danger and oxidizing properties. Step 2: Slowly add sodium hydroxide solution to pretreatment solution A to neutralize perchloric acid and generate sodium perchlorate, thus obtaining mixture B and reducing the risk of highly corrosive perchloric acid. Step 3: Add titanium trichloride waste liquid to mixture B, stir for a period of time, then add alanine solution dropwise to catalyze the reaction and obtain mixture C. Finally, heat mixture C. Step 4: After the reaction is complete, slowly add sodium hydroxide solution to mixture C to adjust the pH to 8.0-9.0, thus obtaining mixture D; Step 5, and the reactions in steps 1 through 4, are all carried out in a fume hood; Step 6: After the mixed liquid is filtered by plate and frame filter press D, the filtrate is reused after evaporation, desalination and biochemical treatment, and the filter residue is collected for resource utilization.

2. The method for safely disposing of waste perchloric acid according to claim 1, characterized in that, In step one, the ratio of water to perchloric acid is 10:1, and the perchloric acid is slowly added dropwise to the water.

3. The method for safely disposing of waste perchloric acid according to claim 1, characterized in that, When the concentration of sodium hydroxide in step two is 15%-20% and the pH of the reaction solution is 7.0-8.0, the addition of sodium hydroxide solution should be stopped.

4. The method for safely disposing of waste perchloric acid according to claim 1, characterized in that, The titanium trichloride waste liquid in step three is a titanium trichloride solution generated during the determination of total iron content in iron ore. The titanium trichloride content is 15%. 1%-5% hydrochloric acid is added to the titanium trichloride solution to ensure that the titanium trichloride solution is acidic.

5. A method for the safe disposal of waste perchloric acid according to claim 1 or 4, characterized in that, In step three, the concentration of alanine solution is 30%-40%, and the reaction temperature is controlled at 50-60℃.

6. The method for safely disposing of waste perchloric acid according to claim 1, characterized in that, The filter residue produced in step five is titanium dioxide, which can be utilized as a resource. The waste liquid produces sodium chloride as a byproduct after evaporation. The resulting evaporation filtrate meets the requirements for reuse after biochemical treatment.

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