A device for treating wastewater containing tetramethylammonium hydroxide

Abstract

The utility model discloses a kind of treatment device of tetramethylammonium hydroxide-containing wastewater, including with the first pH adjusting tank of tetramethylammonium hydroxide-containing wastewater pipeline connection, the first pH adjusting tank outlet is connected with the second pH adjusting tank through feeding pipeline, the second pH adjusting tank outlet is connected with resin adsorption column import end through liquid feeding pipeline, the resin adsorption column outlet end is connected with reverse osmosis membrane equipment import through purification pipeline, the concentrated water outlet of reverse osmosis membrane equipment is connected with the feed tank of tetramethylammonium hydroxide production area through tetramethylammonium salt aqueous solution pipeline, the membrane production water of reverse osmosis membrane equipment is connected with biochemical treatment area equipment through pipeline;The utility model makes that tetramethylammonium hydroxide in wastewater is effectively purified and recycled.

Description

Technical Field

[0001] This utility model relates to the field of tetramethylammonium hydroxide purification and recovery technology, and in particular to a treatment device for wastewater containing tetramethylammonium hydroxide. Background Technology

[0002] Tetramethylammonium hydroxide (TMAH) is widely used in chemical production, especially in silicon wafer manufacturing and photolithography. It is a nitrogen-containing alkaline corrosive chemical, and its demand is increasing daily with the development of the domestic electronic-grade chemical industry. The production and use of TMAH generate large amounts of wastewater containing TMAH. This wastewater contains not only a small amount of TMAH but also many non-ionic impurities and metal ions such as calcium, magnesium, and aluminum. If this wastewater is discharged directly into the environment without any treatment, it will not only seriously affect the stable development of the surrounding ecological environment but also waste TMAH resources.

[0003] Patent application CN105348117A discloses a method and apparatus for recovering tetramethylammonium hydroxide (TMAH). First, TMAH waste liquid is adsorbed by activated carbon, then cooled and crystallized (0-25°C) to separate solid TMAH. The separated solid TMAH is then dissolved in soft water for reuse. This patent application is designed to avoid the resource waste and environmental pollution caused by direct discharge of TMAH waste liquid. Although TMAH is recovered and reused, the activated carbon after adsorption saturation needs to be treated as hazardous waste, and the cooling process is energy-intensive. Ultimately, the TMAH recovery rate is only about 60%.

[0004] Therefore, research on methods for purifying and recycling tetramethylammonium hydroxide, especially addressing the shortcomings of existing wastewater treatment technologies, is urgently needed. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a treatment device for wastewater containing tetramethylammonium hydroxide, so that tetramethylammonium hydroxide in the wastewater can be effectively purified and recycled.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is: a treatment device for wastewater containing tetramethylammonium hydroxide, including a first pH adjustment tank connected to the tetramethylammonium hydroxide wastewater pipeline, the outlet of the first pH adjustment tank being connected to a second pH adjustment tank via a feeding pipeline, the outlet of the second pH adjustment tank being connected to the inlet end of a resin adsorption column via a liquid delivery pipeline, the outlet end of the resin adsorption column being connected to the inlet of a reverse osmosis membrane device via a purification pipeline, the concentrate outlet of the reverse osmosis membrane device being connected to the feeding tank of the tetramethylammonium hydroxide production area via a tetramethylammonium salt aqueous solution pipeline, and the membrane permeate of the reverse osmosis membrane device being connected to the equipment in the biochemical treatment area via a pipeline.

[0007] Preferably, the first pH adjustment tank is equipped with a pH meter, and its acid solution inlet is connected to the acid solution storage tank via a pipeline.

[0008] Preferably, the acid solution in the acid solution storage tank is one of HCl, H2SO4 and HNO3.

[0009] Preferably, the second pH adjustment tank is equipped with a pH meter, and its alkaline solution inlet is connected to the alkaline solution storage tank via a pipeline.

[0010] Preferably, the alkaline solution in the alkaline solution storage tank is one of NaOH, KOH, and TMAH.

[0011] Preferably, when the alkaline solution in the alkaline solution storage tank is TMAH, the alkaline solution storage tank is connected to the tetramethylammonium salt aqueous solution pipeline through a return pipeline.

[0012] Preferably, a valve is provided on the return pipeline.

[0013] Preferably, the resin filling the resin adsorption column is one of sulfonic acid cation exchange resin, aminophosphonic acid resin, and aminocarboxylic acid resin.

[0014] Preferably, the feeding pipeline is also equipped with a pre-filter.

[0015] Preferably, the feeding pipeline, liquid delivery pipeline and purification pipeline are each equipped with corresponding pumping equipment.

[0016] The beneficial effects of this invention are as follows: This invention enables the effective purification and recycling of tetramethylammonium hydroxide in wastewater; it effectively removes non-ionic impurities and metal ions from the wastewater, thereby improving the recovery rate of tetramethylammonium hydroxide in the wastewater; it utilizes a membrane separation system to effectively separate and concentrate the tetramethylammonium salt aqueous solution, resulting in significant energy savings; the produced water is then sent to subsequent biochemical processes for further deep treatment, providing excellent pretreatment for the biochemical system and greatly reducing its load. Attached Figure Description

[0017] Figure 1This is a schematic diagram of a device for treating wastewater containing tetramethylammonium hydroxide;

[0018] Figure 2 This is a schematic diagram of another treatment device for wastewater containing tetramethylammonium hydroxide. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0020] Example 1: As Figure 1 As shown, a treatment device for wastewater containing tetramethylammonium hydroxide includes a first pH adjusting tank 2 connected to a tetramethylammonium hydroxide wastewater pipeline 1. The outlet of the first pH adjusting tank 2 is connected to a second pH adjusting tank 4 via a feed pipeline 3. The outlet of the second pH adjusting tank 4 is connected to the inlet of a resin adsorption column 6 via a liquid delivery pipeline 5. The outlet of the resin adsorption column 6 is connected to the inlet of a reverse osmosis membrane device 8 via a purification pipeline 7. The concentrate outlet of the reverse osmosis membrane device 8 is connected to the feed tank of the tetramethylammonium hydroxide production area via a tetramethylammonium salt aqueous solution pipeline 9. The membrane permeate of the reverse osmosis membrane device 8 is connected to the equipment in the biochemical treatment area via a pipeline. In this embodiment, the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide wastewater pipeline 1 is between 0.5% and 5.0%, and it contains a small amount of non-ionic impurities and metal ions such as calcium, magnesium, and aluminum.

[0021] Preferably, the first pH adjustment tank 2 is equipped with a pH meter, and its acid solution inlet is connected to the acid solution storage tank 10 through a pipeline.

[0022] Preferably, the acid solution in the acid solution storage tank 10 is one of HCl, H2SO4 and HNO3.

[0023] Preferably, the second pH adjusting tank 4 is equipped with a pH meter, and its alkaline solution inlet is connected to the alkaline solution storage tank 11 via a pipeline. In this embodiment, the alkaline solution in the second pH adjusting tank 4 is used to adjust the pH of the tetramethylammonium salt aqueous solution to ≥5.

[0024] Preferably, the alkaline solution in the alkaline solution storage tank 11 is one of NaOH, KOH and TMAH.

[0025] Preferably, such as Figure 2 As shown, when the alkaline solution in the alkaline solution storage tank 11 is TMAH, the alkaline solution storage tank 11 is connected to the tetramethylammonium salt aqueous solution pipeline 9 through the return pipeline 12. This allows for the effective reuse of the treated tetramethylammonium salt aqueous solution.

[0026] Preferably, the return line 12 is equipped with a valve.

[0027] Preferably, the resin filled in the resin adsorption column 6 is one of sulfonic acid cation exchange resin, aminophosphonic acid resin, and aminocarboxylic acid resin. In this embodiment, the flow rate through the column is controlled at 1.5~2 BV / h.

[0028] Preferably, the feeding pipeline 3 is further provided with a pre-filter 13. In this embodiment, after the tetramethylammonium hydroxide wastewater is adjusted with an acid solution in the first pH adjustment tank 2, its pH is ≤7, so that the TMAH ammonium ions in the wastewater and the acid radical ions form a tetramethylammonium salt aqueous solution, and the impure substances in the non-ionic state are insoluble in the salt solution and precipitate out; then when it flows out through the feeding pipeline 3, the crystals precipitated in the material can be filtered out by the pre-filter 13 to prevent them from entering the second pH adjustment tank 4.

[0029] Preferably, the feeding line 3, the liquid delivery line 5, and the purification line 7 are all equipped with corresponding pumping devices.

[0030] In this embodiment, the pH of the influent to the reverse osmosis membrane device 8 is 5.0~9.0, and the operating pressure is controlled at 2.0~2.5MPa, thereby obtaining a high concentration of tetramethylammonium salt aqueous solution.

[0031] The working principle of this embodiment is as follows:

[0032] After adjusting the pH of the tetramethylammonium hydroxide wastewater to ≤7 using an acid solution in the first pH adjustment tank 2, the TMAH ammonium ions in the wastewater react with the acid radicals to form a tetramethylammonium salt aqueous solution, causing non-ionic impurities to precipitate out as insoluble in the salt solution. Then, as the material flows out through the feed line 3, the precipitated crystals are filtered out by the pre-filter 13, preventing them from entering the second pH adjustment tank 4. In the second pH adjustment tank 4, an alkaline solution is used to adjust the pH of the tetramethylammonium salt aqueous solution to ≥5. Then, the chelating resin in the resin adsorption column 6 adsorbs the metal ions in the tetramethylammonium salt aqueous solution, obtaining a purified tetramethylammonium salt aqueous solution. Finally, the purified tetramethylammonium salt aqueous solution is concentrated using the reverse osmosis membrane in the reverse osmosis membrane device 8 to obtain concentrated tetramethylammonium salt, thus completing the treatment of the tetramethylammonium hydroxide wastewater. In addition, the concentrate from the reverse osmosis membrane equipment 8 is sent to the feed tank of the tetramethylammonium hydroxide production area via the tetramethylammonium salt aqueous solution pipeline 9 for reuse, while the membrane permeate from the reverse osmosis membrane equipment 8 is sent to the biochemical treatment area equipment for further treatment via pipeline.

[0033] Example 2: To verify the processing effect of the processing device of Example 1 of the present invention, relevant experiments were conducted in the laboratory. The specific process is as follows:

[0034] Step 1: 2.5L of tetramethylammonium hydroxide waste liquid with a TMAH content of 2.5% was adjusted to pH 3.0 using 4mol / L hydrochloric acid. After standing for 30 minutes, the precipitate was filtered through filter paper to obtain the supernatant, which is the tetramethylammonium salt aqueous solution.

[0035] Step 2: Adjust the pH of the tetramethylammonium salt aqueous solution from Step 1 to 6.0 using a 2.5% tetramethylammonium hydroxide solution. Adsorb the metal ions in the tetramethylammonium salt aqueous solution using a sulfonic acid-type strong cation resin at an adsorption flow rate of 1.5 BV / h and an adsorption volume of 8 BV.

[0036] The contents of the tetramethylammonium salt aqueous solution before and after resin adsorption were determined, and the results are shown in the table below:

[0037]

[0038] As shown in the table above, the resin has a good adsorption effect on various metal ions in the tetramethylammonium salt aqueous solution, thus achieving the purpose of purification.

[0039] Based on the above operating steps, the purified tetramethylammonium salt aqueous solution was concentrated using a reverse osmosis membrane device to obtain a higher concentration of tetramethylammonium salt aqueous solution. The operating pressure was 2.1 MPa, and water was produced using a total reflux concentration method. The treatment effect at different concentration ratios was investigated, with total nitrogen content used instead of tetramethylammonium salt concentration. The results are shown in the table below.

[0040]

[0041] As can be seen from the table above, after RO membrane concentration, a high concentration of tetramethylammonium salt aqueous solution can be obtained, which can be reused in TMAH production. The membrane permeate can be directly fed into the biochemical system for further treatment.

[0042] The above embodiments are merely preferred technical solutions of this utility model and should not be considered as limitations on this utility model. The protection scope of this utility model should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the protection scope of this utility model.

Claims

1. A treatment device for wastewater containing tetramethylammonium hydroxide, comprising a first pH adjusting tank (2) connected to a tetramethylammonium hydroxide wastewater pipeline (1), characterized in that: The outlet of the first pH adjustment tank (2) is connected to the second pH adjustment tank (4) through the feed pipeline (3). The outlet of the second pH adjustment tank (4) is connected to the inlet of the resin adsorption column (6) through the liquid delivery pipeline (5). The outlet of the resin adsorption column (6) is connected to the inlet of the reverse osmosis membrane equipment (8) through the purification pipeline (7). The concentrated water outlet of the reverse osmosis membrane equipment (8) is connected to the feed tank of the tetramethylammonium hydroxide production area through the tetramethylammonium salt aqueous solution pipeline (9). The membrane permeate of the reverse osmosis membrane equipment (8) is connected to the equipment in the biochemical treatment area through the pipeline.

2. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 1, characterized in that: The first pH adjustment tank (2) is equipped with a pH meter, and its acid solution inlet is connected to the acid solution storage tank (10) through a pipeline.

3. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 2, characterized in that: The acid solution in the acid solution storage tank (10) is one of HCl, H2SO4 and HNO3.

4. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 1, characterized in that: The second pH adjustment tank (4) is equipped with a pH meter, and its alkaline solution inlet is connected to the alkaline solution storage tank (11) through a pipeline.

5. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 4, characterized in that: The alkaline solution in the alkaline solution storage tank (11) is one of NaOH, KOH and TMAH.

6. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 5, characterized in that: When the alkaline solution in the alkaline solution storage tank (11) is TMAH, the alkaline solution storage tank (11) is connected to the tetramethylammonium salt aqueous solution pipeline (9) through the return pipeline (12).

7. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 6, characterized in that: A valve is provided on the return pipeline (12).

8. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 1, characterized in that: The resin filling the resin adsorption column (6) is one of sulfonic acid cation exchange resin, aminophosphonic acid resin and aminocarboxylic acid resin.

9. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 1, characterized in that: The feed line (3) is also equipped with a pre-filter (13).

10. The treatment device for wastewater containing tetramethylammonium hydroxide according to claim 1, characterized in that: The feeding line (3), liquid delivery line (5) and purification line (7) are all equipped with corresponding pumping devices.

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