阅读说明：本技术 一种石墨烯生产废水的处理方法及其应用 (Treatment method and application of graphene production wastewater ) 是由 梁亚涛 朱红芳 黎元生 陈勤立 李桂林 雷伟健 陈钢 杨正高 于 2021-03-11 设计创作，主要内容包括：本发明公开了一种石墨烯生产废水的处理方法及其应用。本发明的石墨烯生产废水的处理方法,能够减少中和物的投入、降低中和物的投入成本,并回收得到能用于肥料生产的混合物。在石墨烯制备过程中使用上述石墨烯生产废水的处理方法,能降低石墨烯生产废水的处理成本,生产过程环保。(The invention discloses a treatment method and application of graphene production wastewater. The method for treating the graphene production wastewater can reduce the input of the neutralized substances, reduce the input cost of the neutralized substances, and recover and obtain the mixture capable of being used for fertilizer production. The treatment method for the graphene production wastewater is used in the graphene preparation process, so that the treatment cost of the graphene production wastewater can be reduced, and the production process is environment-friendly.)

1. A treatment method of graphene production wastewater is characterized by comprising the following steps: the method comprises the following steps: adding a first-stage neutralized substance into the graphene production wastewater to adjust the pH value, adding a second-stage neutralized substance to adjust the pH value, introducing air, filtering out precipitates, and purifying the filtrate to obtain a mixture.

2. The method for treating wastewater from graphene production according to claim 1, wherein: adding a first-stage neutralizing substance to adjust the pH value to 2-5.

3. The method for treating wastewater from graphene production according to claim 1, wherein: adding a second-stage neutralizing substance to adjust the pH value to 7-9.

4. The method for treating wastewater from graphene production according to claim 1 or 2, wherein: the primary neutralizing substance is at least one of magnesium oxide and magnesium hydroxide.

5. The method for treating wastewater from graphene production according to claim 1 or 3, wherein: the second-stage neutralizer is potassium hydroxide.

6. The method for treating wastewater from graphene production according to claim 1, wherein: the precipitate is a flocculate of manganese metahydroxide and graphene oxide suspensions.

7. The method for treating wastewater from graphene production according to claim 1, wherein: the purification comprises drying and crystallization, wherein the drying is at least one selected from steam drying and reduced pressure distillation.

8. The method for treating wastewater from graphene production according to claim 1, wherein: the mixture is a mixture of magnesium sulfate and potassium sulfate.

9. The method for treating wastewater from graphene production according to claim 1, wherein: the graphene production wastewater contains H⁺、K⁺、Mn²⁺、SO₄ ^2-And a graphene oxide suspension.

10. Application of the method for treating the graphene production wastewater according to any one of claims 1 to 9 in preparation of graphene.

Technical Field

The invention belongs to the technical field of wastewater treatment, and particularly relates to a treatment method and application of graphene production wastewater.

Background

Graphene is a polymer made of carbon atoms in sp²The honeycomb planar film formed by the hybridization mode has a unique two-dimensional nano structure, has the advantages of high electron transmission rate, good electrical conductivity, high thermal conductivity and the like, is the thinnest but the hardest nano material with the best electrical and thermal conductivity at present, and has good application prospects in the fields of physics, materials science, electronic information, computers, aerospace and the like.

The preparation method of graphene is diversified, but the industrial production mainly comprises a chemical method and a physical method. The physical method for preparing graphene is mainly used for stripping graphite into graphene through shearing, the production efficiency is low, and the prepared graphene is thick in sheet layer. The chemical method is mainly to prepare the graphene by carrying out oxidation intercalation on graphite and then stripping and reducing. Potassium permanganate, concentrated sulfuric acid and the like are often used in the chemical method graphene preparation process, and a large amount of H is generated⁺、K⁺、Mn²⁺、SO₄ ^2-And waste water such as graphene oxide suspended matter, which is problematic in that it is difficult to treat large amounts of waste water.

In the prior art, methods for treating graphene production wastewater by a chemical method are few, and although some technologies can prepare calcium sulfate whiskers and recover calcium sulfate for producing fertilizers, soluble inorganic salts in the waste liquid are difficult to remove, acid-containing waste liquid is concentrated, so that equipment is corroded greatly, the water solubility of calcium oxide is not high, more waste liquid is generated although the calcium sulfate whiskers are prepared, and actual production amplification is difficult to realize; some technologies add manganese raw materials when treating wastewater, filter and distill under reduced pressure after adjusting pH to obtain manganese sulfate crystals, but the treatment process not only needs to supplement oxalic acid or hydrogen peroxide as a reducing agent, but also has great difference in treatment efficiency, poor stability in the treatment process and no actual amplification condition. Some technologies utilize alkaline substances containing potassium to carry out neutralization conditions to obtain manganese byproducts and potassium salts, and although the process is environment-friendly and does not introduce other impurities, potassium is deficient in China, the cost of potassium salts is high, the cost for treating wastewater is too high, and the process is not suitable for large-scale wastewater treatment.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the first aspect of the invention provides a method for treating wastewater from graphene production, which can reduce the input of neutralized substances, reduce the input cost of neutralized substances, and recover and obtain a mixture capable of being used for fertilizer production.

In a second aspect of the present invention, an application of the above method for treating wastewater from graphene production is provided.

According to a first aspect of the invention, a method for treating wastewater from graphene production is provided, which comprises the following steps: adding a first-stage neutralized substance into the graphene production wastewater to adjust the pH value, adding a second-stage neutralized substance to adjust the pH value, introducing air, filtering out precipitates, and purifying the filtrate to obtain a mixture.

In some embodiments of the present invention, the pH value is adjusted to 2-5 by adding a primary neutralizer.

In some preferred embodiments of the present invention, the pH value of the solution is adjusted to 7 to 9 by adding the two-stage neutralizer.

In some more preferred embodiments of the present invention, the one-stage neutralizer is at least one selected from magnesium oxide and magnesium hydroxide. OH formed by dispersing magnesium oxide or hydroxide in water^-Neutralizing most of H in the graphene production wastewater⁺The magnesium oxide or magnesium hydroxide is used for neutralization treatment, the heat release amount in the treatment process is small, the magnesium oxide or magnesium hydroxide has small molecular weight and belongs to divalent alkali, and compared with other alkali, the magnesium oxide or magnesium hydroxide is less in usage amount and generates less solid waste when equivalent graphene production wastewater is neutralized.

In some more preferred embodiments of the present invention, the second-stage neutralizer is potassium hydroxide. One part is neutralized by magnesium oxide or magnesium hydroxide, and only a small amount of potassium hydroxide, Mn, is added in the two-part treatment²⁺Excess OH^-Manganese hydroxide is formed by reaction, the manganese hydroxide has low solubility in water and is easy to precipitate, and the manganese hydroxide is easy to flocculate with graphene oxide suspended matters in the precipitation process, so that Mn in the graphene production wastewater can be removed²⁺And graphene oxide suspensions. The addition of the neutralizing substance twice can greatly reduce the consumption of potassium hydroxide in the treatment process of the wastewater from graphene production, and other impurities can not be introduced, so that the purification step is simplified while the treatment cost is reduced.

In some more preferred embodiments of the present invention, the potassium hydroxide is an aqueous solution of potassium hydroxide having a mass concentration of 10% to 30%; more preferably a potassium hydroxide aqueous solution having a mass concentration of 20% to 30%.

In some more preferred embodiments of the present invention, the precipitate is a floc of manganese metahydroxide and graphene oxide suspensions.

In some more preferred embodiments of the present invention, the purification comprises drying and crystallization. And drying and dehydrating the filtrate, wherein magnesium sulfate heptahydrate is easily formed in a magnesium sulfate solution in the filtrate, and crystallization can be carried out after a small amount of water is removed, so that a mixture of potassium sulfate and magnesium sulfate hydrate is finally obtained, and the mixture is an excellent production raw material of the compound fertilizer.

In some more preferred embodiments of the present invention, the drying is at least one selected from the group consisting of steam drying and vacuum distillation.

In some more preferred embodiments of the present invention, the above mixture is a mixture of magnesium sulfate and potassium sulfate.

In some more preferred embodiments of the present invention, the graphene production wastewater contains H⁺、K⁺、Mn²⁺、SO₄ ^2-And a graphene oxide suspension.

In some more preferred embodiments of the present invention, the mass concentration of the graphene production wastewater is 0.1% to 98%; more preferably 1% to 47%; more preferably 5% to 45%.

According to a second aspect of the invention, the application of the method for treating the graphene production wastewater in preparing graphene is provided. The treatment method for the graphene production wastewater is used in the graphene preparation process, so that the treatment cost of the graphene production wastewater can be reduced, and the production process is environment-friendly.

The technical scheme of the invention has the beneficial effects that:

when the graphene production wastewater is treated, the graphene production wastewater is neutralized by magnesium oxide or magnesium hydroxide, the heat release amount in the treatment process is small, the magnesium oxide or magnesium hydroxide has small molecular weight and belongs to divalent alkali, and compared with other alkali, the magnesium oxide or magnesium hydroxide is less in usage amount when equivalent waste acid water is neutralized, and less solid waste is generated. When the pH value of the first-stage neutralized substance is adjusted to a preset target, a very small amount of second-stage neutralized substance potassium hydroxide solution is added to remove Mn²⁺And graphene oxide suspended matters and the like, so that the cost is not obviously increased, and other impurities are not introduced. And when the filtrate is dried, magnesium sulfate and potassium sulfate remain in the filtrate, the magnesium sulfate is easy to form magnesium sulfate heptahydrate, the magnesium sulfate heptahydrate can be crystallized and separated out, the energy consumption is low during drying, and finally, a mixture of the potassium sulfate and the magnesium sulfate hydrate is obtained, and the mixture is a high-quality compound fertilizer. The whole wastewater treatment process is efficient, environment-friendly, low in treatment cost, less in investment equipment and easy to enlarge and popularize.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention.

Example 1

A treatment method of graphene production wastewater comprises the following steps:

taking 1000mL of graphene production wastewater, wherein the mass concentration of the wastewater is about 35%, slowly adding 155g of magnesium oxide, stirring, testing the pH value to be 4 after the graphene production wastewater is completely dissolved, adding 3mL of potassium hydroxide solution with the mass concentration of 20% to adjust the pH value to be 9, continuously stirring, introducing air, stopping stirring after the solution is brown, filtering while hot to separate a filter cake from filtrate, taking the filtrate, and carrying out reduced pressure distillation to obtain a mixture of potassium sulfate and magnesium sulfate.

Example 2

A treatment method of graphene production wastewater comprises the following steps:

taking 1000mL of graphene production wastewater, wherein the mass concentration of the wastewater is about 15%, slowly adding 88g of magnesium hydroxide, stirring, testing the pH value to be 5 after the graphene production wastewater is completely dissolved, adding 5mL of 10% potassium hydroxide solution to adjust the pH value to be 8, continuously stirring, introducing air, stopping stirring after the solution is brown, filtering while hot to separate a filter cake from a filtrate, taking the filtrate, and carrying out reduced pressure distillation to obtain a mixture of potassium sulfate and magnesium sulfate.

Example 3

A treatment method of graphene production wastewater comprises the following steps:

taking 1000mL of graphene production wastewater, wherein the mass concentration of the wastewater is about 23%, slowly adding 93g of magnesium oxide, stirring, testing the pH value to be 5 after the graphene production wastewater is completely dissolved, adding 5mL of potassium hydroxide solution with the mass concentration of 10% to adjust the pH value to be 8, continuously stirring, introducing air, stopping stirring after the solution is brown, filtering while hot to separate a filter cake from filtrate, taking the filtrate, and carrying out reduced pressure distillation to obtain a mixture of potassium sulfate and magnesium sulfate.

Example 4

Taking 1000mL of graphene production wastewater, wherein the mass concentration of the wastewater is about 23%, slowly adding 93g of magnesium oxide, stirring, testing the pH value to be 5 after the graphene production wastewater is completely dissolved, adding 5mL of potassium hydroxide solution with the mass concentration of 10% to adjust the pH value to be 8, continuously stirring, introducing air, stopping stirring after the solution is brown, filtering while hot to separate a filter cake from filtrate, taking the filtrate, and carrying out reduced pressure distillation to obtain a mixture of potassium sulfate and magnesium sulfate.

Comparative example 1

A treatment method of graphene production wastewater comprises the following steps:

1000mL of graphene production wastewater is taken, the mass concentration of the wastewater is about 35%, 571g (264 g theoretically) of calcium hydroxide is slowly added and then stirred, the solubility of the calcium hydroxide is not enough, and the formed calcium sulfate is coated on the surface of the calcium hydroxide, so that the using amount of the calcium hydroxide is greatly increased, even if the actual using amount is far more than the theoretical using amount, the waste acid water cannot be neutralized to be neutral, and the wastewater with the concentration of 35% is not suitable for being neutralized by the calcium hydroxide.

Comparative example 2

A treatment method of graphene production wastewater comprises the following steps:

taking 1000mL of graphene production wastewater, wherein the mass concentration of the wastewater is about 35%, slowly adding 414g of potassium hydroxide, stirring, testing the pH value to be 4 after the graphene production wastewater is completely dissolved, adding 6mL of potassium hydroxide solution with the mass concentration of 20%, continuously stirring, introducing air, stopping stirring after the solution is brown, filtering while hot, separating a filter cake from filtrate, taking the filtrate, and carrying out reduced pressure distillation to obtain a potassium sulfate mixture.

Test examples

The treatment conditions of the graphene production wastewater in examples 1 to 6 and comparative examples 1 and 2 are shown in table 1, and the quality of the mixture obtained by purifying the treated filtrate is taken.

TABLE 1

In table 1, as can be seen from comparison of example 1 and comparative examples 1 and 2, magnesium oxide or magnesium hydroxide is a divalent base and has a small molecular weight, and when equivalent graphene production wastewater is treated, the consumption amount is much lower than that of potassium hydroxide and calcium hydroxide, and less solid waste is generated. In particular, although calcium hydroxide is also a divalent alkali, when the wastewater from graphene production is neutralized, calcium sulfate precipitates are easily attached to the surface of calcium hydroxide to prevent the calcium hydroxide from being further dissolved, the usage amount of the calcium hydroxide is further increased, and the high-concentration wastewater water cannot be directly neutralized. On the other hand, 1/4, in which magnesium oxide or magnesium hydroxide is less expensive than potassium hydroxide, introduces potassium hydroxide in the second stage neutralization process, but the amount of potassium hydroxide introduced is very small and does not significantly increase the cost. Finally, after neutralization is finished, magnesium sulfate in the filtrate is easy to be saturated and crystallized and separated out in the distillation process to form crystals of hydrated magnesium sulfate, magnesium sulfate heptahydrate can be formed maximally according to different crystallization conditions, and evaporation cost is further reduced, and the quality of the mixture obtained after the filtrate is purified in example 1 is also the highest as seen in comparative example 1 and comparative examples 1 and 2. Therefore, the method for treating the graphene production wastewater is a simple, efficient and easily-amplified green route.

The embodiments of the present invention have been described in detail, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.