CN109305677B

CN109305677B - Method for removing graphite carbon in nano diamond ash

Info

Publication number: CN109305677B
Application number: CN201811416894.7A
Authority: CN
Inventors: 陈守文; 解立新; 陈永光; 丁立满; 杨筱; 张在东
Original assignee: Jiangsu Jinhaifeng Hard Material Technology Co ltd; Nanjing Jinrui Lifeng Hard Material Technology Co ltd
Current assignee: Jiangsu Jinhaifeng Hard Material Technology Co ltd; Nanjing Jinrui Lifeng Hard Material Technology Co ltd
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2021-06-29
Anticipated expiration: 2038-11-26
Also published as: CN109305677A

Abstract

The invention discloses a method for removing graphite carbon in a nano diamond ash, which is characterized by comprising the following steps: adding the detonation ash of the nano-diamond into a high-temperature resistant medium, and heating to 250-^oAnd C, adding nitrate, and carrying out heat preservation reaction for 0.5-10 hours at the temperature of 300-600 ℃. And after cooling, adding water to dissolve and separate diamond powder, filtering, washing and drying to obtain a purified nano diamond product. The method can directly provide high-purity products without further treatment under the condition that the content of metal oxides, salts and silicon dioxide in the ash is small, and has the advantages of simple process steps, low equipment requirement, high product purity, safe and environment-friendly production process and the like.

Description

Method for removing graphite carbon in nano diamond ash

Technical Field

The invention relates to a method for purifying diamond, in particular to a method for removing graphite-state carbon in nano-diamond ash prepared based on an explosive detonation mode.

Background

The nano-diamond has wide application in the fields of ultra-precision polishing, high-grade grinding (lubricating) oil, wear-resistant material additives, wear-resistant surface composite plating and the like.

Under special technological conditions, the explosive can be prepared by detonationA detonation ash mixture containing a quantity of diamond-like carbon. Among the ash impurities, graphitic carbon is the largest and most difficult to remove. At present, the removal of graphite carbon mainly comprises two types of chemical oxidation and high-temperature air oxidation. Valerii Yu Dolmatov, Ultracrystal Diamond-Synthesis, Properties and Applications (Willian Andrew Publishing, New York,2006) describes a variety of chemical oxidation techniques, including perchloric acid, concentrated sulfuric acid + nitric acid, sulfuric acid + chromium trioxide, ozone, nitric acid, etc., wherein sulfuric acid + nitric acid has been on an industrial scale, but this method is carried out at high temperature and high pressure (280 ℃), and requires high equipment requirements, severe corrosion, and low product purity. CN1385366A and CN01114455.6 disclose oxidation purification methods using potassium permanganate and concentrated sulfuric acid at the temperature of 100 ℃ and 250 ℃, the removal effect of the method on graphite-state carbon is not very obvious, and the waste water contains heavy metal manganese, so that the environmental problem is more. CN106587046B discloses a method for removing graphite carbon by using nitrate, potassium permanganate and hydrogen peroxide in a sulfuric acid medium and treating at 75-90 ℃, and experiments prove that the method has very limited effect on removing the graphite carbon. CN1400162A discloses that removing graphite carbon in boiling state of concentrated sulfuric acid + concentrated nitric acid has poor effect of removing graphite carbon, and the utilization rate is low because nitric acid is easily decomposed at high temperature. The use of HClO is reported in the literature "functional materials" (2000, 31 (1): 56-57)₄，H₂SO₄+K₂Cr₂O₇、H₂SO₄+KMnO₄The oxidation treatment can remove the graphite carbon, although the conclusion is that three methods can effectively remove the graphite carbon, the perchloric acid boiling method has higher cost and H₂SO₄+K₂Cr₂O₇And H₂SO₄+KMnO₄The effects of both methods are to be further verified. The documents "New technology and technology" (2006 (1): 110-. Therefore, there is a need for further improvements in the removal of graphitic carbon.

Disclosure of Invention

The invention aims to provide a method and a process for efficiently removing graphitic carbon in a nano-diamond detonation ash material. The method has the advantages of simple process steps, low raw material cost, high product purity and the like, and the production process is safe and does not involve the problems of heavy metal emission and the like.

The technical solution for realizing the purpose of the invention is as follows: a method for removing graphite carbon in nano-diamond ash comprises the following steps: adding the detonation ash of the nano-diamond into a high-temperature-resistant medium, heating to 500 ℃ at 250 ℃, adding nitrate, and carrying out heat preservation reaction for 0.5-10 hours at 600 ℃ at 300 ℃. And after cooling, adding water to dissolve and separate diamond powder, filtering, washing and drying to obtain a purified nano diamond product.

Furthermore, the high temperature resistant medium adopts low-melting point and high-boiling point substances, preferably sodium hydroxide or potassium hydroxide, and the reaction temperature is controlled to be above 400 ℃ under the condition that the potassium hydroxide is used as the reaction medium.

Furthermore, the dosage of the high-temperature resistant medium is 2 to 15 times, preferably 5 to 10 times of the mass of the diamond detonation ash.

Further, the nitrate is sodium nitrate or potassium nitrate, and the dosage of the nitrate is 1 to 6 times, preferably 3 to 5 times of the mass of the diamond detonation ash.

Compared with the prior art, the invention has the following remarkable advantages: (1) the method has the advantages of simple process, low equipment requirement, high product purity, safe and environment-friendly production process and the like. (2) The nano-diamond produced by the method can completely meet the application in the related fields, in particular to the fields of ultra-precision polishing, high-grade grinding (lubricating) oil, wear-resistant material additives, wear-resistant surface composite plating and the like. (3) Under the condition that the content of metal oxide, salt and silicon dioxide in the ash is small, the high-purity product can be directly provided without further treatment.

Drawings

FIG. 1 is an XRD spectrum of a product and pure graphite powder of the example of the present invention.

Detailed Description

The method for removing the graphite carbon in the nano-diamond ash material adopts nitrate oxidation treatment in a high-temperature alkaline liquid medium, the graphite carbon reacts with the nitrate to form carbon dioxide, and the carbon dioxide further reacts with the alkaline medium to generate carbonate. The reaction with nitrate at high temperature, taking sodium hydroxide as an alkaline medium as an example, is as follows:

5C+4NaNO₃+6NaOH→5Na₂CO₃+2N₂↑+3H₂O↑

it can be seen that the final product was sodium carbonate with excess sodium hydroxide, nitrogen and water vapor. Sodium hydroxide is reacted with carbon dioxide to obtain sodium carbonate which can be recovered as a byproduct, and the whole production process does not generate wastes and is a green production process.

In order to realize the recovery of the by-products, the optimal production process preferably adopts the medium and the oxidant as the same metal, namely: the alkaline medium is selected from sodium hydroxide, and the oxidant is selected from sodium nitrate; the alkaline medium is potassium hydroxide, and the oxidant is potassium nitrate.

The following examples are further illustrative of the present invention and are not intended to limit the scope of the present invention.

The first embodiment is as follows:

20kg of sodium hydroxide and 4kg of detonation ash are added into a 100L stainless steel reaction kettle, the temperature is raised to 350 ℃, 18kg of sodium nitrate is added, the temperature is raised to 450 ℃, and the temperature is kept for 8 hours. After cooling, sufficient water is added to dissolve the sodium hydroxide and sodium carbonate. Filtering, and fully washing with deionized water until the filtrate is neutral. Filtering and drying to obtain 1.58kg of offwhite product, wherein the yield is 39.5 percent.

The XRD pattern of the product is shown in figure 1. As can be seen in fig. 1, the main characteristic peak of graphite is at 28 °, while the product shows almost no graphite peak at 28 °, indicating that the graphite carbon in the diamond detonation ash has been substantially completely removed.

Examples two to six:

the second to sixth embodiments have substantially the same operation processes as the first embodiment. The reaction was carried out in a 100L stainless steel autoclave with the remaining basic conditions and results set forth in Table 1.

TABLE 1 basic conditions and results of the examples

^aThe graphite carbon removal was judged from the peak at about 28 ° in XRD.

Claims

1. The method for removing the graphite carbon in the nano-diamond ash is characterized by comprising the following steps: adding the detonation ash of the nano-diamond into a high-temperature-resistant medium, heating to 500 ℃ at 250 ℃, adding nitrate, and carrying out heat preservation reaction for 0.5-10 hours at 600 ℃ at 300 ℃; after cooling, adding water to dissolve and separate diamond powder, filtering, washing and drying to obtain a purified nano diamond product;

wherein, the high-temperature resistant medium adopts sodium hydroxide or potassium hydroxide;

the nitrate is sodium nitrate or potassium nitrate.

2. The method as set forth in claim 1, wherein the reaction is carried out at 400-600 ℃ for 0.5-10 hours when potassium hydroxide is used as the high temperature-resistant medium.

3. The method of claim 1, wherein the refractory medium is present in an amount of 2 to 15 times the mass of the diamond detonation ash.

4. The method of claim 1, wherein the refractory medium is present in an amount of 5 to 10 times the mass of the diamond detonation ash.

5. The method of claim 1, wherein the nitrate is present in an amount of 1 to 6 times the mass of the diamond detonation ash.

6. The method of claim 1, wherein the nitrate is present in an amount of 3 to 5 times the mass of the diamond detonation ash.