Wastewater treatment method of tetramethylammonium hydroxide

Abstract

The invention relates to the technical field of wastewater treatment, and proposes a method for treating wastewater containing tetramethylammonium hydroxide, comprising the following steps: adjusting the pH value of wastewater containing tetramethylammonium hydroxide to 7-7.5, adding hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica, mixing, reacting, settling, and discharging water. Through the above technical scheme, the problem of low decomposition rate of tetramethylammonium hydroxide in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for treating tetramethylammonium hydroxide wastewater. Background Art

[0002] As a strong alkaline substance, tetramethylammonium hydroxide is widely used as a developer in the electronics industry. However, it produces toxic wastewater containing tetramethylammonium hydroxide during use. If this wastewater is directly discharged, it will pollute the environment. Therefore, it is necessary to adopt an effective wastewater treatment method to remove tetramethylammonium hydroxide from the wastewater.

[0003] At present, the common method is to use microorganisms or bleach to decompose tetramethylammonium hydroxide in wastewater before discharging it. The rate of microbial decomposition of tetramethylammonium hydroxide is slow, and a large area of ​​site is required, which cannot meet the needs of the current semiconductor industry. The method of decomposing tetramethylammonium hydroxide by adding bleach has the defect of low decomposition rate. Therefore, it is of great significance to develop a new method for treating tetramethylammonium hydroxide wastewater. Summary of the invention

[0004] The invention provides a method for treating wastewater of tetramethylammonium hydroxide, which solves the problem of low decomposition rate of tetramethylammonium hydroxide in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The invention provides a method for treating wastewater containing tetramethylammonium hydroxide, which comprises the following steps: adjusting the pH value of wastewater containing tetramethylammonium hydroxide to 7-7.5, adding hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica, mixing, reacting, settling and discharging water.

[0007] As a further technical solution, the mass ratio of the hypochlorite to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 40-50:50, the mass ratio of the sodium bicarbonate to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 5-25:50, the mass ratio of the sodium acetate to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 4-8:50, and the mass ratio of the mesoporous silica to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 5-10:50.

[0008] In the present invention, the decomposition rate of tetramethylammonium hydroxide is further improved by optimizing the added amounts of hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica.

[0009] As a further technical solution, the mass ratio of the sodium bicarbonate to the sodium acetate is 2-2.5:1.

[0010] In the present invention, when the mass ratio of sodium bicarbonate to sodium acetate is 2-2.5:1, it helps to further improve the decomposition rate of tetramethylammonium hydroxide.

[0011] As a further technical solution, the mesoporous silica is mesoporous silica loaded with lanthanum ions.

[0012] In the present invention, by loading lanthanum ions on the mesoporous silica, the decomposition reaction can be further promoted, thereby further improving the decomposition rate of tetramethylammonium hydroxide.

[0013] As a further technical solution, the preparation method of the mesoporous silica loaded with lanthanum ions is as follows: dissolving lanthanum salt in water, adding mesoporous silica, dispersing evenly, concentrating, and calcining to obtain the mesoporous silica loaded with lanthanum ions.

[0014] As a further technical solution, the lanthanum salt includes one or both of lanthanum nitrate and lanthanum chloride.

[0015] As a further technical solution, the mass ratio of the lanthanum salt to the mesoporous silica is 1~5:20.

[0016] In the present invention, when the mass ratio of the lanthanum salt to the mesoporous silica is 1 to 5:20, it helps to further improve the decomposition rate of tetramethylammonium hydroxide.

[0017] As a further technical solution, during the calcination, the temperature is 200-300° C. and the time is 1-2 hours.

[0018] As a further technical solution, the hypochlorite includes one or more of sodium hypochlorite, calcium hypochlorite, and potassium hypochlorite.

[0019] As a further technical solution, the pore size of the mesoporous silica is 2-20 nm.

[0020] As a further technical solution, during the reaction, the temperature is 20-25°C and the time is 6-8h.

[0021] The working principle and beneficial effects of the present invention are:

[0022] In the present invention, the wastewater treatment method of tetramethylammonium hydroxide has the advantage of high decomposition rate. In particular, by adding sodium bicarbonate and sodium acetate in the wastewater treatment process, the two synergistically enhance the efficiency, thereby significantly improving the decomposition rate of tetramethylammonium hydroxide. In addition, the addition of mesoporous silica can promote the decomposition reaction, thereby improving the decomposition rate of tetramethylammonium hydroxide. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the following examples and comparative examples, unless otherwise specified, the mesoporous silica has a model of JK-04-007-100 and a pore size of 9 nm, purchased from Nanjing Chico Biotechnology Co., Ltd.

[0025] Example 1

[0026] A method for treating wastewater containing tetramethylammonium hydroxide comprises the following steps: adjusting the pH value of wastewater containing tetramethylammonium hydroxide to 7, adding sodium hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica, mixing, reacting at 25°C for 6 hours, settling and discharging water;

[0027] Among them, the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide-containing wastewater is 50 mg / L, the added amount of sodium hypochlorite is 35 mg / L, the added amount of sodium bicarbonate is 3 mg / L, the added amount of sodium acetate is 1 mg / L, and the added amount of mesoporous silica is 3 mg / L.

[0028] Example 2

[0029] A method for treating wastewater containing tetramethylammonium hydroxide comprises the following steps: adjusting the pH value of wastewater containing tetramethylammonium hydroxide to 7.5, adding sodium hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica, mixing, reacting at 20° C. for 8 hours, settling and discharging water;

[0030] Among them, the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide-containing wastewater is 50 mg / L, the added amount of sodium hypochlorite is 55 mg / L, the added amount of sodium bicarbonate is 30 mg / L, the added amount of sodium acetate is 10 mg / L, and the added amount of mesoporous silica is 15 mg / L.

[0031] Example 3

[0032] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of sodium hypochlorite added is 35 mg / L, the amount of sodium bicarbonate added is 3 mg / L, the amount of sodium acetate added is 1 mg / L, and the amount of mesoporous silica added is 3 mg / L.

[0033] Example 4

[0034] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of sodium hypochlorite added is 40 mg / L, the amount of sodium bicarbonate added is 5 mg / L, the amount of sodium acetate added is 4 mg / L, and the amount of mesoporous silica added is 5 mg / L.

[0035] Example 5

[0036] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of sodium hypochlorite added is 50 mg / L, the amount of sodium bicarbonate added is 25 mg / L, the amount of sodium acetate added is 8 mg / L, and the amount of mesoporous silica added is 10 mg / L.

[0037] Example 6

[0038] The difference between this embodiment and embodiment 5 is only that, in this embodiment, the addition amount of sodium bicarbonate is 13 mg / L.

[0039] Example 7

[0040] The difference between this embodiment and embodiment 5 is that, in this embodiment, the addition amount of sodium bicarbonate is 17 mg / L, and the addition amount of sodium acetate is 4 mg / L.

[0041] Example 8

[0042] The difference between this embodiment and embodiment 5 is that, in this embodiment, the addition amount of sodium bicarbonate is 14 mg / L, and the addition amount of sodium acetate is 7 mg / L.

[0043] Example 9

[0044] The difference between this embodiment and embodiment 5 is that, in this embodiment, the addition amount of sodium bicarbonate is 15 mg / L, and the addition amount of sodium acetate is 6 mg / L.

[0045] Example 10

[0046] The difference between this embodiment and embodiment 9 is that in this embodiment, the mesoporous silica is mesoporous silica loaded with lanthanum ions, and the preparation method of the mesoporous silica loaded with lanthanum ions is as follows: lanthanum chloride is dissolved in water, mesoporous silica is added, dispersed evenly, concentrated under reduced pressure, and calcined at 250° C. for 1.5 h to obtain mesoporous silica loaded with lanthanum ions;

[0047] Among them, the mass ratio of lanthanum chloride to mesoporous silica is 1:30.

[0048] Embodiment 11

[0049] The only difference between this embodiment and embodiment 10 is that, in this embodiment, lanthanum chloride is replaced by an equal amount of lanthanum nitrate.

[0050] Example 12

[0051] The only difference between this embodiment and embodiment 10 is that in this embodiment, the mass ratio of lanthanum chloride to mesoporous silica is 2:5.

[0052] Embodiment 13

[0053] The only difference between this embodiment and embodiment 10 is that in this embodiment, the mass ratio of lanthanum chloride to mesoporous silica is 1:20.

[0054] Embodiment 14

[0055] The only difference between this embodiment and embodiment 10 is that in this embodiment, the mass ratio of lanthanum chloride to mesoporous silica is 1:4.

[0056] Comparative Example 1

[0057] The difference between this comparative example and Example 1 is that in this comparative example, no sodium bicarbonate is added and the addition amount of sodium acetate is 4 mg / L.

[0058] Comparative Example 2

[0059] The difference between this comparative example and Example 1 is that, in this comparative example, no sodium acetate is added and the addition amount of sodium bicarbonate is 4 mg / L.

[0060] Comparative Example 3

[0061] The difference between this comparative example and Example 1 is only that, in this comparative example, sodium bicarbonate and sodium acetate were not added.

[0062] Comparative Example 4

[0063] The only difference between this comparative example and Example 1 is that in this comparative example, mesoporous silica is not added.

[0064] The concentration of tetramethylammonium hydroxide after the water of Examples 1 to 14 and Comparative Examples 1 to 4 was detected, and the decomposition rate of tetramethylammonium hydroxide was calculated according to the following formula: decomposition rate = concentration of tetramethylammonium hydroxide after the water / concentration of tetramethylammonium hydroxide before treatment × 100%. The calculation results are shown in Table 1 below.

[0065] Table 1 Decomposition rate of tetramethylammonium hydroxide

[0066]

[0067] The decomposition rate of tetramethylammonium hydroxide in Example 1 is significantly higher than that in Comparative Examples 1 to 3, which indicates that by adding sodium bicarbonate and sodium acetate in the wastewater treatment process, the synergistic effect of the two can greatly improve the decomposition rate of tetramethylammonium hydroxide. The decomposition rate of tetramethylammonium hydroxide in Example 1 is significantly higher than that in Comparative Example 4, which indicates that the addition of mesoporous silica can significantly improve the decomposition rate of tetramethylammonium hydroxide.

[0068] The decomposition rate of tetramethylammonium hydroxide in Examples 4 to 5 is higher than that in Examples 2 to 3, which indicates that when the mass ratio of hypochlorite to tetramethylammonium hydroxide in wastewater containing tetramethylammonium hydroxide is 40 to 50:50, the mass ratio of sodium bicarbonate to tetramethylammonium hydroxide in wastewater containing tetramethylammonium hydroxide is 5 to 25:50, the mass ratio of sodium acetate to tetramethylammonium hydroxide in wastewater containing tetramethylammonium hydroxide is 4 to 8:50, and the mass ratio of mesoporous silica to tetramethylammonium hydroxide in wastewater containing tetramethylammonium hydroxide is 5 to 10:50, it is helpful to further improve the decomposition rate of tetramethylammonium hydroxide. The decomposition rate of tetramethylammonium hydroxide in Examples 8 to 9 is higher than that in Examples 6 to 7, which indicates that when the mass ratio of sodium bicarbonate to sodium acetate is 2 to 2.5:1, it is helpful to further improve the decomposition rate of tetramethylammonium hydroxide.

[0069] The decomposition rate of tetramethylammonium hydroxide in Examples 10 to 14 is higher than that in Example 9, which indicates that loading lanthanum ions on mesoporous silica helps to further improve the decomposition rate of tetramethylammonium hydroxide. The decomposition rate of tetramethylammonium hydroxide in Examples 13 to 14 is higher than that in Examples 10 and 12, which indicates that when the mass ratio of lanthanum salt to mesoporous silica is 1 to 5:20, it helps to further improve the decomposition rate of tetramethylammonium hydroxide.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating wastewater of tetramethylammonium hydroxide, characterized in that: The following steps are involved: The pH value of the wastewater containing tetramethylammonium hydroxide is adjusted to 7-7.5, hypochlorite, sodium bicarbonate, sodium acetate and mesoporous silica are added, mixed, reacted, settled and discharged; The mass ratio of the hypochlorite to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 40-50:50, the mass ratio of the sodium bicarbonate to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 5-25:50, the mass ratio of the sodium acetate to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 4-8:50, and the mass ratio of the mesoporous silica to the tetramethylammonium hydroxide in the wastewater containing tetramethylammonium hydroxide is 5-10:50; The mass ratio of sodium bicarbonate to sodium acetate is 2-2.5:1; The mesoporous silica is mesoporous silica loaded with lanthanum ions; The preparation method of the mesoporous silica loaded with lanthanum ions is as follows: dissolving lanthanum salt in water, adding mesoporous silica, dispersing evenly, concentrating, and calcining to obtain the mesoporous silica loaded with lanthanum ions; The mass ratio of the lanthanum salt to the mesoporous silica is 1-5:20; The lanthanum salt includes one or both of lanthanum nitrate and lanthanum chloride.

2. The method for treating wastewater of tetramethylammonium hydroxide according to claim 1, wherein: The hypochlorite includes one or more of sodium hypochlorite, calcium hypochlorite and potassium hypochlorite.

3. The method for treating wastewater of tetramethylammonium hydroxide according to claim 1, wherein: The pore size of the mesoporous silica is 5-20 nm.

4. The method for treating wastewater of tetramethylammonium hydroxide according to claim 1, wherein: During the reaction, the temperature is 20-25° C. and the reaction time is 6-8 hours.

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