CN107491110B - Alumina dispersion liquid with stable pH and acid-base buffering and preparation method thereof - Google Patents
Alumina dispersion liquid with stable pH and acid-base buffering and preparation method thereof Download PDFInfo
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Abstract
100 parts by weight of aluminum salt 0.1-1 part, aluminum oxide 1-10 parts and deionized water in balance, dissolving aluminum salt in 49-49.9 parts of deionized water to prepare an aluminum salt solution, dispersing aluminum oxide in 40-49 parts of deionized water to prepare an aluminum oxide dispersion, and mixing and stirring the aluminum salt solution and the aluminum oxide dispersion uniformly to obtain the acidic aluminum oxide dispersion with stable pH. The invention can effectively control the pH of the alumina dispersion liquid by controlling the adding amount of the aluminum salt, has the advantages of short time consumption, safety, no pollution, low cost, simple preparation and the like, simultaneously the prepared alumina dispersion liquid has a certain acid-base buffering effect, and a small amount of acid or alkali is added into the dispersion liquid, so that the pH deviation of the dispersion liquid is small, or when a reactant is added into the dispersion liquid, if a small amount of hydrogen ions or hydroxyl ions are generated in the reaction process, the pH deviation of the dispersion liquid is small, and the pH of the dispersion liquid tends to be recovered within a certain time.
Description
Technical Field
the invention relates to a method for stabilizing the pH value of an acidic alumina dispersion liquid, belonging to the field of preparation and production of acidic alumina dispersion liquids.
background
The nano alumina dispersion liquid has a series of advantages of high uniformity, high dispersity, high stability and the like, so that the nano alumina dispersion liquid can be widely applied to a plurality of industrial fields. Such as protective agent for cashmere and nylon yarn, dispersing agent in carpet cleaning agent; as an abrasive in chemical mechanical polishing, as a polishing agent for paper surfaces, glass fiber and metal surfaces, and the like. When the pH is higher than 4, the alumina dispersion is liable to form gel, which is disadvantageous for industrial use, and the pH of the dispersion has a significant influence on the dispersion stability of alumina, so that the pH of the alumina dispersion is usually maintained between 3 and 4 in industrial use. Therefore, controlling the pH stability of alumina dispersions is a key technology in the field of alumina applications. The conventional method of adjusting the pH of an alumina dispersion with a mineral acid (e.g., nitric acid) can temporarily adjust the pH to 3-4, but cannot stabilize the pH and even drift the pH within a short half hour, which is extremely disadvantageous for production applications. Moreover, nitric acid is corrosive, and has potential safety hazard in the operation process. Therefore, it is important to provide an efficient and safe method for stabilizing the pH of acidic alumina dispersions for use in alumina dispersions.
Currently, there are documents disclosing methods by which the pH of alumina dispersions can be stabilized. For example, U.S. Pat. No. 4, 6364920, 1 discloses a method for stabilizing the pH of acidic alumina dispersions in the presence of an iodate by adding an organic acid such as formic acid, acetic acid, maleic acid, citric acid, etc. to the dispersion and heating to reflux for 15 minutes. Compared with the traditional method of adjusting the pH by inorganic acid such as nitric acid, the method has less pH drift (the pH value of the traditional nitric acid adjusted alumina dispersion liquid is shifted by 0.74 after 24 hours, and the optimal shift value is 0.07 after 24 hours), but the method needs to be heated to boiling and refluxed to achieve the optimal effect, the operation is complicated, and the pH drift value under the optimal condition is still large, so the method is not beneficial to large-batch use. US4676928 discloses a method for preventing gelation of an alumina dispersion in the pH range of 5-9 by adjusting the pH of the dispersion with hydrochloric acid, nitric acid, acetic acid, etc. although effective in controlling the dispersion without forming a gel, the addition of an acid is corrosive and requires heating in an environment of 70 ℃ or higher, which presents a safety hazard; moreover, the pH range is too large, and the method is not suitable for being applied to the field of fine chemical production.
Compared with the prior art, the method for stabilizing the pH of the acidic alumina dispersion has the advantages of safety, no pollution, short time consumption, simple preparation, low cost and the like, and is widely applied to the fields of paper coatings of acidic systems, textile cool feeling agents, scratch resistance of water-based coatings, chemical mechanical polishing and the like.
Disclosure of Invention
aiming at the defects of the existing acidic alumina dispersion pH stabilization technology, the invention provides the alumina dispersion with stable pH, which has the advantages of low cost, safety, short time consumption, no pollution and certain acid-base buffering function, and also provides a preparation method of the dispersion.
the alumina dispersion liquid with stable pH and acid-base buffering comprises, by weight, 100 parts of aluminum salt 0.1-1 part, 1-10 parts of alumina and the balance of deionized water.
The preparation method of the alumina dispersion liquid with stable pH comprises the following steps:
Weighing 0.1-1 part of aluminum salt, 1-10 parts of aluminum oxide and the balance of deionized water by 100 parts by weight, dissolving the aluminum salt in 49-49.9 parts of deionized water to prepare an aluminum salt solution, dispersing the aluminum oxide in 40-49 parts of deionized water to prepare an aluminum oxide dispersion liquid, and mixing and stirring the aluminum salt solution and the aluminum oxide dispersion liquid uniformly to obtain an acidic aluminum oxide dispersion liquid with stable pH;
the aluminum salt is aluminum chloride or aluminum nitrate.
the stirring time is 15-30 minutes.
The pH is 3-4.
The pH of the alumina dispersion can be controlled by controlling the amount of aluminum salt added. A small amount of acid or alkali is added into the acidic alumina dispersion liquid prepared by the invention, the pH drift is obviously small, and the mixed liquid has the tendency of restoring to the pH of the acidic alumina dispersion liquid within a certain period of time. The acid is nitric acid. The alkali is sodium hydroxide or potassium hydroxide.
The method effectively controls the pH of the alumina dispersion liquid by controlling the adding amount of the aluminum salt, and has the advantages of short time consumption, safety, no pollution, low cost, simple preparation and the like.
Drawings
FIG. 1 is a graphical representation of the pH of acidic alumina dispersions prepared in accordance with the present invention over 24 hours as a function of time.
FIG. 2 is a graphical representation of the pH of the acidic alumina dispersion prepared in accordance with the present invention as a function of time over 9 hours after addition of base to bring the pH 10% away from its pH.
FIG. 3 is a graphical representation of pH as a function of time over 24 hours after adjusting the pH of a 5% alumina dispersion with nitric acid.
Detailed Description
Example 1
In this example, a 1% alumina and 0.1% aluminum nitrate system was selected (1% by mass of alumina and 0.1% by mass of aluminum nitrate in the prepared pH stable alumina dispersion). The specific process is as follows:
test of pH stability
(1) Weighing 0.1g of aluminum nitrate, adding the aluminum nitrate into 49.9g of deionized water, and fully stirring until the aluminum nitrate is completely dissolved to prepare an aluminum nitrate solution;
(2) Weighing 1g of alumina powder, adding the alumina powder into 49g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum nitrate solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum nitrate solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals and the results are given in the following table:
TABLE 1 pH of alumina dispersion over time after addition of aluminum nitrate
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.85 | 3.85 | 3.85 | 3.85 | 3.85 | 3.85 |
The pH of the alumina dispersion prepared in this example was stable at 3.85 over 24 hours. See also the graph of pH over time over 24 hours given by figure 1.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example were taken, and 20. mu.l of a 0.5M potassium hydroxide solution was added to adjust the pH to 10% from the pH itself, and the pH of the solution was measured at intervals. The results are shown in the following table:
TABLE 2.1 variation of the pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 4.35 | 4.11 | 4.08 | 4.06 |
see also FIG. 2 for a graph showing the change in pH over time within 9 hours after addition of base to shift the pH from its own pH of 10%.
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 10. mu.l of a 0.5M nitric acid solution to adjust the pH to minus 10% from the pH (the same applies hereinafter), and the pH of the solution was measured at intervals. The results are shown in the following table:
TABLE 2.2 variation of the pH of the dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.48 | 3.60 | 3.89 | 3.86 |
example 2
In this example, a 1% alumina and 1% aluminum nitrate system was selected (1% by mass of alumina and 1% by mass of aluminum nitrate in the prepared pH stable alumina dispersion). The specific process is as follows:
Test of pH stability
(1) Weighing 1g of aluminum nitrate, adding the aluminum nitrate into 49g of deionized water, and fully stirring until the aluminum nitrate is completely dissolved to prepare an aluminum nitrate solution;
(2) weighing 1g of alumina powder, adding the alumina powder into 49g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum nitrate solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 15 minutes to uniformly mix the aluminum nitrate solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum nitrate
The alumina dispersion prepared in this example stabilized in pH 3.35-3.36 over 24 hours with a variance of 0.01. See also the graph of pH over time over 24 hours given by figure 1.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 3.65, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.65 | 3.54 | 3.47 | 3.39 |
See also FIG. 2 for a graph showing the change in pH over time within 9 hours after addition of base to shift the pH from its own pH of 10%.
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 10. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.00, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.00 | 3.17 | 3.18 | 3.31 |
Example 3
This example selects a 5% alumina to 0.5% aluminum nitrate system (5% alumina by mass and 0.5% aluminum nitrate by mass in the pH stable alumina dispersion prepared). The specific process is as follows:
test of pH stability
(1) weighing 0.5g of aluminum nitrate, adding the aluminum nitrate into 49.5g of deionized water, and fully stirring until the aluminum nitrate is completely dissolved to prepare an aluminum nitrate solution;
(2) weighing 5g of alumina powder, adding the alumina powder into 45g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum nitrate solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum nitrate solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum nitrate
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.80 | 3.80 | 3.80 | 3.79 | 3.80 | 3.79 |
The alumina dispersion prepared in this example stabilized in pH 3.79 to 3.80 over 24 hours with a variation of 0.01. See also the graph of pH over time over 24 hours given by figure 1.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M sodium hydroxide solution to adjust the pH to 4.00, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of sodium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 4.00 | 3.91 | 3.81 | 3.80 |
see also FIG. 2 for a graph showing the change in pH over time within 9 hours after addition of base to shift the pH from its own pH of 10%.
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.54, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.54 | 3.75 | 3.74 | 3.79 |
example 4
this example selects a 10% alumina to 0.1% aluminum nitrate system (10% alumina by mass and 0.1% aluminum nitrate by mass in the pH stable alumina dispersion prepared). The specific process is as follows:
Test of pH stability
(1) weighing 0.1g of aluminum nitrate, adding the aluminum nitrate into 49.9g of deionized water, and fully stirring until the aluminum nitrate is completely dissolved to prepare an aluminum nitrate solution;
(2) weighing 10g of alumina powder, adding the alumina powder into 40g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) Mixing the prepared aluminum nitrate solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 20 minutes to uniformly mix the aluminum nitrate solution and the aluminum oxide dispersion liquid, and preparing the aluminum oxide dispersion liquid with stable pH and a buffering effect;
(4) the pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum nitrate
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 4.27 | 4.27 | 4.27 | 4.27 | 4.26 | 4.27 |
the alumina dispersion prepared in this example stabilized in pH 4.26-4.27 over 24 hours with a 0.01 change. See also the graph of pH over time over 24 hours given by figure 1.
test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 4.50, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 4.50 | 4.38 | 4.33 | 4.28 |
see also FIG. 2 for a graph showing the change in pH over time within 9 hours after addition of base to shift the pH from its own pH of 10%.
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 13. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.77, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.77 | 4.11 | 4.11 | 4.20 |
Example 5
In this example, a 10% alumina to 1% aluminum nitrate system was selected (10% by mass of alumina and 1% by mass of aluminum nitrate in the prepared pH stable alumina dispersion). The specific process is as follows:
Test of pH stability
(1) Weighing 1g of aluminum nitrate, adding the aluminum nitrate into 49g of deionized water, and fully stirring until the aluminum nitrate is completely dissolved to prepare an aluminum nitrate solution;
(2) Weighing 10g of alumina powder, adding the alumina powder into 40g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) Mixing the prepared aluminum nitrate solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum nitrate solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum nitrate
| time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.65 | 3.65 | 3.66 | 3.66 | 3.65 | 3.65 |
The pH of the alumina dispersion prepared in this example stabilized at 3.65 to 3.66 with a 0.01 change over 24 hours. See also the graph of pH over time over 24 hours given by figure 1.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 3.91, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.91 | 3.77 | 3.70 | 3.70 |
see also FIG. 2 for a graph showing the change in pH over time within 9 hours after addition of base to shift the pH from its own pH of 10%.
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 12. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.11, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| time (h) | 0 | 3 | 6 | 9 |
| pH | 3.11 | 3.63 | 3.63 | 3.65 |
Example 6
In this example, a 1% alumina to 0.1% aluminum chloride system was selected (1% by mass of alumina and 0.1% by mass of aluminum chloride in the prepared pH-stabilized alumina dispersion). The specific process is as follows:
Test of pH stability
(1) Weighing 0.1g of aluminum chloride, adding into 49.9g of deionized water, and fully stirring until the aluminum chloride is completely dissolved to prepare an aluminum chloride solution;
(2) Weighing 1g of alumina powder, adding the alumina powder into 49g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum chloride solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum chloride solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum chloride
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.98 | 4.01 | 4.01 | 4.01 | 4.02 | 4.01 |
The pH of the alumina dispersion prepared in this example stabilized between 3.98 and 4.03 over 24 hours, with a 0.05 change.
test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example were taken, and 20. mu.l of a 0.5M sodium hydroxide solution was added to adjust the pH to 4.71, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of dispersion with time after addition of sodium hydroxide
| time (h) | 0 | 3 | 6 | 9 |
| pH | 4.71 | 4.62 | 4.30 | 4.20 |
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.60, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of dispersion with time after addition of nitric acid
Example 7
In this example, a 1% alumina and 1% aluminum chloride system was selected (1% by mass of alumina and 1% by mass of aluminum chloride in the prepared pH-stable alumina dispersion). The specific process is as follows:
Test of pH stability
(1) Weighing 1g of aluminum chloride, adding into 49g of deionized water, and fully stirring until the aluminum chloride is completely dissolved to prepare an aluminum chloride solution;
(2) weighing 1g of alumina powder, adding the alumina powder into 49g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum chloride solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum chloride solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) the pH of the solution was measured at intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of aluminum chloride
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.24 | 3.24 | 3.26 | 3.25 | 3.26 | 3.26 |
The alumina dispersion prepared in this example stabilized a pH of 3.24 to 3.26 over 24 hours, with a variance of 0.02.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 3.66, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.66 | 3.58 | 3.50 | 3.49 |
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 2.90, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 2.90 | 3.15 | 3.18 | 3.28 |
example 8
this example selects a 5% alumina to 0.5% aluminum chloride system (5% alumina by mass and 0.5% aluminum chloride by mass in the pH stable alumina dispersion prepared). The specific process is as follows:
Test of pH stability
(1) Weighing 0.5g of aluminum chloride, adding into 49.5g of deionized water, and fully stirring until the aluminum chloride is completely dissolved to prepare an aluminum chloride solution;
(2) Weighing 5g of alumina powder, adding the alumina powder into 45g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) Mixing the prepared aluminum chloride solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum chloride solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of aluminum chloride
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.73 | 3.73 | 3.72 | 3.73 | 3.73 | 3.73 |
The alumina dispersion prepared in this example stabilized in pH 3.72 to 3.73 over 24 hours with a variance of 0.01.
Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 4.17, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of potassium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 4.17 | 3.90 | 3.79 | 3.77 |
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.42, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
change of pH of dispersion with time after addition of nitric acid
| time (h) | 0 | 3 | 6 | 9 |
| pH | 3.42 | 3.55 | 3.55 | 3.55 |
Example 9
In this example, a 10% alumina to 0.1% aluminum chloride system was selected (10% by mass of alumina and 0.1% by mass of aluminum chloride in the prepared pH-stabilized alumina dispersion). The specific process is as follows:
test of pH stability
(1) weighing 0.1g of aluminum chloride, adding into 49.9g of deionized water, and fully stirring until the aluminum chloride is completely dissolved to prepare an aluminum chloride solution;
(2) Weighing 10g of alumina powder, adding the alumina powder into 40g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) Mixing the prepared aluminum chloride solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum chloride solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) the pH of the solution was measured at intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of aluminum chloride
| Time (h) | 0.5 | 2.5 | 5.0 | 6.0 | 8.0 | 10.0 | 24.0 |
| pH | 4.26 | 4.24 | 4.26 | 4.26 | 4.27 | 4.26 | 4.26 |
The alumina dispersion prepared in this example stabilized a pH of 4.24 to 4.27 over 24 hours, with a variance of 0.03. Test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example were taken, 20. mu.l of a 0.5M sodium hydroxide solution was added thereto to adjust the pH to 4.77, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of sodium hydroxide
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 4.77 | 4.62 | 4.53 | 4.36 |
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.68, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.68 | 4.24 | 4.24 | 4.24 |
example 10
In this example, a 10% alumina to 1% aluminum chloride system was selected (10% by mass of alumina and 1% by mass of aluminum chloride in the prepared pH-stable alumina dispersion). The specific process is as follows:
Test of pH stability
(1) weighing 1g of aluminum chloride, adding into 49g of deionized water, and fully stirring until the aluminum chloride is completely dissolved to prepare an aluminum chloride solution;
(2) weighing 10g of alumina powder, adding the alumina powder into 40g of deionized water, and fully stirring to uniformly disperse the alumina powder to prepare alumina dispersion liquid;
(3) mixing the prepared aluminum chloride solution and the prepared aluminum oxide dispersion liquid in equal volume, stirring for 30 minutes to uniformly mix the aluminum chloride solution and the aluminum oxide dispersion liquid to prepare the aluminum oxide dispersion liquid with stable pH;
(4) The pH of the solution was measured at intervals. The results are shown in the following table:
change of pH of the dispersion with time after addition of aluminum chloride
| Time (h) | 0.5 | 2.5 | 5.0 | 7.5 | 10.0 | 24.0 |
| pH | 3.50 | 3.50 | 3.51 | 3.53 | 3.53 | 3.53 |
The pH of the alumina dispersion prepared in this example stabilized between 3.50 and 3.53 over 24 hours, with a 0.03 change.
test for pH buffer Effect
(1) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M potassium hydroxide solution to adjust the pH to 4.02, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of the dispersion with time after addition of potassium hydroxide
| time (h) | 0 | 3 | 6 | 9 |
| pH | 4.02 | 3.83 | 3.80 | 3.75 |
(2) 10ml of the pH-stabilized alumina dispersion prepared in this example was added with 20. mu.l of a 0.5M nitric acid solution to adjust the pH to 3.20, and the pH of the solution was measured at regular intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
| Time (h) | 0 | 3 | 6 | 9 |
| pH | 3.20 | 3.30 | 3.34 | 3.40 |
Comparative example
The comparative example selects a 5% alumina dispersion, and the specific process is as follows:
test of pH stability
(1) weighing 0.5g of alumina, adding the alumina into 9.5g of deionized water, and fully stirring to uniformly disperse the alumina to prepare alumina dispersion liquid;
(2) Adding 40 mu l of nitric acid solution with the concentration of 1M into the alumina dispersion liquid in the step (1);
(3) The pH of the solution was measured at intervals. The results are shown in the following table:
Change of pH of dispersion with time after addition of nitric acid
it can be seen that the alumina dispersion without the addition of aluminum salt showed a large change in the pH of the dispersion after the addition of nitric acid. This change is also shown in FIG. 3, which shows the pH as a function of time within 24 hours after the pH of a 5% alumina dispersion has been adjusted with nitric acid.
test for pH buffer Effect
(1) 10ml of the alumina dispersion prepared in this comparative example was taken, and 20. mu.l of a 0.5M potassium hydroxide solution was added, and the pH thereof became 7.88.
(2) 10ml of the alumina dispersion prepared in this comparative example was taken, and 20. mu.l of a 0.5M nitric acid solution was added, and the pH thereof became 2.68.
It can be seen that the alumina dispersions of the same concentration without the addition of the aluminum salt, compared to examples 3 and 8, have a much greater pH change than the alumina dispersions prepared according to the invention when the same amount of acid or base is added at the same initial pH.
Claims (5)
1. An alumina dispersion with stable pH and acid-base buffering is characterized in that: based on 100 parts by weight, the aluminum salt comprises 0.1-1 part of aluminum salt, 1-10 parts of aluminum oxide and the balance of deionized water.
2. a method of preparing the pH stable acid-base buffered alumina dispersion of claim 1, comprising: based on 100 parts by weight, 0.1-1 part of aluminum salt, 1-10 parts of alumina and the balance of deionized water, dissolving the aluminum salt in 49-49.9 parts of deionized water to prepare an aluminum salt solution, dispersing the alumina in 40-49 parts of deionized water to prepare an alumina dispersion, and mixing and stirring the aluminum salt solution and the alumina dispersion uniformly to obtain the acidic alumina dispersion with stable pH.
3. the method of preparing a pH stable acid-base buffered alumina dispersion according to claim 1, wherein: the aluminum salt is aluminum chloride or aluminum nitrate.
4. the method of preparing a pH stable acid-base buffered alumina dispersion according to claim 2, wherein: the stirring time in the process of uniformly mixing and stirring the aluminum salt solution and the alumina dispersion liquid is 15-30 minutes.
5. the method of preparing a pH stable acid-base buffered alumina dispersion according to claim 2, wherein: the pH is 3-4.
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