CN1833765A

CN1833765A - MnO film for filtering carbon nanotube effluent, its prepn. and use

Info

Publication number: CN1833765A
Application number: CN 200610024359
Authority: CN
Inventors: 高濂; 范武刚
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2006-03-03
Filing date: 2006-03-03
Publication date: 2006-09-20
Anticipated expiration: 2026-03-03
Also published as: CN100384522C

Abstract

A manganese oxide film for filtering the sewage containing carbon nanotubes is composed of mangnese oxide nanowires with tens microns in length, which can be easily combined to become nanobundles. The fine gap between said nanobundles (less than 1 micron) can allow the fine substances to pass through it. Said MnO2 film is prepared from potassium sulfate, potassium persulfate and manganese sulfate through mixing in distilled water and hydrothermal synthesis.

Description

Manganese oxide film capable of being used for filtering carbon nanotube waste liquid, preparation and application

Technical Field

The invention relates to a preparation method and application of an inorganic nano-film material, in particular to a method for synthesizing manganese oxide (MnO) for treating and filtering carbon nano-tube waste liquid₂) Thin film methods. The prepared film is used for treating carbon nanotube waste liquid, and belongs to the field of nano materials.

Technical Field

Since s.iijima discovered carbon nanotubes in 1991, great interest has been drawn to their unique electrical, optical and mechanical properties, and their research fields relate to the fields of electronics, catalyst supports, displays, drug delivery and hydrogen storage. But the problem that comes with it is the generation and disposal of carbon nanotube waste liquid. Carbon nanotubes have been shown to be hazardous to humans in recent studies and to have more serious consequences after inhalation than carbon black and quartz (Lam C.W, James, J.T. Toxicol. sic.77(2004), 126-); the results of Ding et al show that: toxicity of carbon tubes can also be caused by contact with skin cells, and a unit cell can die after contacting dozens of multi-walled carbon tubes. (Lianghao Ding, Jackie Stilwll, tintingling Zhang et al, Nanoletters, n1051748 o). Therefore, attention must be paid to and research on the damage and protection methods of the carbon nanotubes and the waste liquid treatment. Yuan et al synthesized paper-like OMS-2 membrane using potassium persulfate, potassium sulfate, manganese sulfate and water as raw materials, the synthesis temperature was 250 deg.C, and the product required natural drying in distilled water at 85 deg.C for 24 hours, and successfully captured gold particles (Jikang Yuan, Kate Laubernds, advanced materials, 16(2004), 1729-. At present, few papers are available on the aspect of carbon nanotube waste liquid treatment, laboratories generally adopt organic polymer microporous filter membranes or centrifugation methods to separate and recover carbon nanotubes, and both methods are not suitable for large-scale recovery of carbon nanotube waste liquid, and the organic thin film itself may be dissolved by some organic solvents. Whether a simple, convenient and effective reusable filtering film which is resistant to organic matter dissolution and corrosion is used for filtering carbon tube waste liquid is very significant.

Disclosure of Invention

The invention aims to provide a preparation method of an inorganic film capable of being used for treating carbon nanotube waste liquid, and the film is used for filtering carbon nanotube waste liquid containing a surfactant and an organic solvent, so that the harm to the environment and the human health can be reduced.

The invention is characterized in that: the inorganic manganese oxide film with good performance is prepared and successfully used for treating the carbon nano tube waste liquid.

The method comprises the following specific steps:

(1) adding potassium sulfate, potassium persulfate and manganese sulfate (all analytically pure) into distilled water according to a proportion to prepare a solution, wherein the molar concentration ranges of the reagents are respectively 0.175-0.195M, 0.175-0.195M and 0.11-0.138M: the mixture is magnetically stirred evenly and then transferred into a high-pressure kettle.

(2) The autoclave hydrothermal treatment adopts a two-step method, wherein the first step is heating at 160 ℃ for 30 hours, and then heating to 220 ℃ and 240 ℃ for 3 days.

The oxidation reaction equation can be expressed as:

(3) 200-1000ml of distilled water is added into the obtained product, and the mixture is magnetically stirred for 2 hours and then is filtered and washed by a vacuum filtration device.

(4) The product obtained in the step (3) is a black and gray paper-shaped film consisting of very fine nanowires, the thickness of the film is between 0.1 and 0.8mm, and the size and the shape can be adjusted according to requirements. The length of the nano-wire can reach dozens of micrometers, and the diameter is between 20 and 40 nanometers. And a nanobeam consisting of tightly bound nanowires is formed, with a gap (less than 1 micron) between the beams allowing the passage of fine material, while carbon nanotubes (typically more than microns in length) are trapped. The film was placed in a vacuum oven at 70 ℃ and dried for 10-15 hours.

(5) The film is used as a filter membrane for a vacuum filtration device, and then a truncated carbon nanotube solution containing a surfactant is poured into the vacuum filtration device for vacuum filtration. The truncated carbon nanotube solution is prepared through reflux treatment of multiwall carbon nanotube in concentrated sulfuric acid and concentrated nitric acid in the volume ratio of 3 to 1 at 140 deg.c for 10 hr, washing and stoving. Then adding surfactant 2198A and deionized water for ultrasonic treatment for 1 hour.

(6) The carbon nanotubes were removed by baking the carbon nanotube-containing film in a muffle furnace at 500 deg.C for 5 hours to remove the carbon nanotubes while the film itself remained intact.

Drawings

Figure 1 SEM photograph of inorganic thin film before filtration,

FIG. 2 SEM images (60 ℃ C. oven) of the treated carbon nanotube solution of the film (a) and (b) show a large amount of surfactant-containing carbon nanotubes at different magnifications (c) showing a clean inorganic film surface.

FIG. 3 TEM photograph of truncated carbon nanotubes dispersed with 2198A surfactant

FIG. 4 photograph of inorganic filter film

Detailed Description

The following non-limiting examples further illustrate the embodiments and effects; thereby setting off the essential features and significant advances of the present invention.

Example 1

Adding 20mmol potassium sulfate, potassium persulfate and manganese sulfate into 40ml distilled water according to the molar ratio of 3: 2, and transferring into an autoclave after magnetic stirring. The hydrothermal treatment is carried out by heating at 160 ℃ for 30 hours, then heating to 220 ℃ for 3 days. Adding 500ml distilled water into the obtained product, magnetically stirring for 2 hours, and then carrying out suction filtration and washing by using a vacuum filtration device. The product is a black and gray paper-shaped film consisting of nanowires with the diameter of 20-40nm, the film is put into a vacuum oven at 70 ℃ for drying for 12 hours (figure 1), and the product can be folded in any direction without breaking (figure 4).

Example 2

40mmol potassium sulfate, potassium persulfate and manganese sulfate are added into 80ml distilled water according to the molar ratio of 3.1: 2.1, and the mixture is transferred into an autoclave after being evenly stirred by magnetic force. The hydrothermal treatment is carried out by heating at 160 ℃ for 30 hours, then heating to 220 ℃ for 3 days. 1000ml of distilled water is added into the obtained product, and the mixture is magnetically stirred for 2 hours and then is filtered and washed by a vacuum filtration device. The appearance of the product is black gray paper-shaped film, and the film is put into a vacuum oven for drying for 12 hours at 70 ℃. The membrane (FIG. 2c) was used as a filter on a vacuum filtration apparatus, and then a truncated carbon nanotube solution containing 2198A surfactant (FIG. 3) was poured and filtered by vacuum pump. The film containing the carbon tubes was removed (fig. 2a, b) and the carbon tubes were removed by baking in a muffle furnace at 500 c for 5 hours while the film itself remained intact and was reusable.

Claims

1. The manganese oxide inorganic film is characterized by consisting of manganese oxide nanowires with the length of dozens of microns and the diameter of 20-40nm, and the thickness of the film is between 0.1-0.8 mm.

2. The manganese oxide inorganic thin film according to claim 1, wherein said nanowires are tightly bound into nanobeams, and a gap of 1 μm exists between the bundles.

3. The manganese oxide inorganic thin film according to claim 1 or 2, wherein the thin film is black and gray, and the shape and size thereof are adjusted as required.

4. A method for preparing a manganese oxide inorganic thin film according to any one of claims 1, 2 or 3, characterized by comprising the steps of:

(a) adding potassium sulfate, potassium persulfate and manganese sulfate as raw materials into distilled water, and uniformly stirring by magnetic force;

(b) adding the solution obtained in the step (a) into an autoclave, and heating the solution at the hydrothermal treatment temperature of 160-;

(c) adding the product obtained in the step (b) into distilled water and stirring for 2 hours;

(d) carrying out suction filtration on the solution obtained in the step (c) by using a vacuum suction filtration device, and washing by using distilled water to obtain a film;

(e) and (d) drying the film obtained in the step (d) in a vacuum oven at 70 ℃.

Wherein, the molar concentrations of the potassium sulfate, the potassium persulfate and the manganese sulfate are respectively 0.175-0.195M, 0.175-0.195M and 0.11-0.138M;

5. the method for preparing a manganese oxide inorganic thin film according to claim 4, characterized in that after the hydrothermal treatment, the solution is diluted with 200-1000ml of distilled water during stirring.

6. The method of claim 4, wherein the vacuum drying time is 10 to 15 hours.

7. Use of an inorganic manganese oxide film according to claim 1, 2 or 3, wherein said inorganic manganese oxide film is capable of retaining highly dispersed and truncated carbon nanotubes containing surfactant on the film when the carbon nanotube solution is filtered through the film.

8. Use of the manganese oxide inorganic thin film according to claim 7, wherein: after the film is baked in air at 500 ℃ for 5 hours, the carbon nanotubes can be removed and the film itself can be recycled.