CN101306808B

CN101306808B - Centrifugal separation process of carbon nano-tubes by density gradient method

Info

Publication number: CN101306808B
Application number: CN2008100400329A
Authority: CN
Inventors: 邓小勇; 熊冬梅; 孙昱飞; 吴飞; 陈雯婷; 王海芳; 焦正; 刘元方
Original assignee: SHANGHAI UNIVERSITY
Current assignee: SHANGHAI UNIVERSITY
Priority date: 2008-07-01
Filing date: 2008-07-01
Publication date: 2010-07-07
Anticipated expiration: 2028-07-01
Also published as: CN101306808A

Abstract

The invention relates to a method for centrifugal separation of carbon nanotubes with a density gradient method. The method comprises the following steps: ultrasonically dispersing carbon nanotubes in an aqueous solution; preparing sucrose solutions with respective concentrations of 5%, 10%, 15%, 20% and 25%, according to mass percentage; sequentially and slowly adding a certain amount of sucrose solution into a same centrifuge tube to preparing a gradient solution; slowly dropping the ultrasonically dispersed carbon nanotube solution on the surface of the gradient solution, centrifuging with a horizontal rotor at 4,000rpm for 60min, and slowly sucking out the centrifuged mixed solution in equal two parts according to the percentages of solutions composing the gradient solution; and obtaining carbon nanotubes with different lengths. The inventive method has the advantage of simple process, can obtain carbon nanotubes with uniform length, and can be applied in the field of drug carriers.

Description

The method of centrifugal separation process of carbon nano-tubes by density gradient

Technical field

The present invention relates to the method for a kind of method of separating carbon nano-tube, particularly a kind of centrifugal separation process of carbon nano-tubes by density gradient.

Background technology

Since 1991 and 1993 find multi-walled carbon nano-tubes and Single Walled Carbon Nanotube respectively, carbon nanotube (CNTs) has caused the extensive concern of each subject with the performance of the machinery of its excellence, electronics, physics, chemical aspect, be considered to have great application prospect, comprising electron device, engineering materials, catalysis, absorption-separation, memory device, electrode materials, biomedicine etc. at wide spectrum.

The production method of carbon current nanotube mainly contains arc discharge method, laser ablation method, chemical Vapor deposition process.The carbon nanotube quality of different batches production differs greatly, and as foreign matter content, carbon length of tube etc., this phenomenon is especially common in Single Walled Carbon Nanotube.The carbon nanotube acid treatment is to be in daily use and practical treatment process, but the phenomenon that carbon pipe range weak point differs also often appears in the pipe after handling, and it differs and can reach 10 times, even 100 times.

Carbon nanotube is applied to pharmaceutical carrier and is considered to a very promising field, and the carbon pipe that length differs greatly is applied to pharmaceutical carrier, must have the difference owing to the caused carrier band effect that differs of itself length.For the application of better biological aspect, it is very necessary obtaining length isostatic carbon nanotube, and in a sense, it is narrow more to wish to use size range, the carbon nanotube of weak point.

The method of separating the different lengths carbon nanotube now mainly contains gel electrophoresis and various chromatographic technique.And the nanotube of the weak point that often obtains has major diameter enrichment to a great extent, cause long thin short and thick phenomenon, and the time that needs is long, and isolating amount is few.

Summary of the invention

The purpose of this invention is to provide a kind of method that adopts density gradient method to separate the carbon nanotube of different lengths.

For achieving the above object, the present invention adopts following technical scheme:

A kind of method of density gradient method separating carbon nano-tube is characterized in that the concrete steps of this method are:

A.. will be made into the aqueous solution that concentration is 0.5～1.5mg/ml with the nitration mixture processed carbon nanotubes, ultra-sonic dispersion fully disperses carbon nanotube;

B. sucrose is made into mass percent respectively and is 5%, 10%, 15%, 20%, 25% the aqueous solution, get isopyknic solution successively by the order from the high density to the lower concentration and be mixed with gradient solution;

C. lentamente step a gained dispersion liquid is joined in the gradient solution of step b gained; The volume ratio of dispersion liquid and gradient solution is 1: 5;

D.4000rpm, horizontal rotor is centrifugal under the 60min condition;

E. according to the umber of gradient solution, with the slow sucking-off of mixed solution five equilibrium after centrifugal; Finally obtain the different carbon nanotube of length.

Above-mentioned carbon nanotube is a multi-walled carbon nano-tubes.

The method of density gradient centrifugation to be sample carry out in certain inertia gradient media (saccharose gradient) centrifugation or sedimentation equilibrium promptly is assigned to particle under certain centrifugal force in the gradient on some specific position, forms the not separation method of same district band.The advantage of this method is: 1. good separating effect can once obtain purer particle; 2. wide accommodation can separate the particle with factor in precipitation difference, can separate the particle that certain buoyant density is arranged again; 3. particle can not overstock distortion, can keep seed activity, and prevents that established district band is owing to convection current causes mixing.

The present invention adopts the method for density gradient centrifugation to come separating carbon nano-tube, makes finally can separate to obtain the continuous and narrower carbon nanotube of scope of size.The inventive method technology is simple, and is easy to operate, can realize suitability for industrialized production.

Description of drawings

Fig. 1 is the embodiment of the invention one a centrifugal back the superiors carbon nanotube electromicroscopic photograph.

Fig. 2 is the 3rd layer of carbon nanotube electromicroscopic photograph in the embodiment of the invention one centrifugal back.

Fig. 3 is the embodiment of the invention one a centrifugal back orlop carbon nanotube electromicroscopic photograph.

Embodiment

Embodiment one:

(1) at first, take by weighing 30mg through nitration mixture (V with electronic balance _{The vitriol oil}: V _{Concentrated nitric acid}=3: the 1) multi-walled carbon nano-tubes after the supersound process, be well-dispersed in the 30ml deionized water multi-walled carbon nano-tubes is ultrasonic, form the carbon nanotube dispersion liquid.

(2) make density gradient: taking by weighing 20g sucrose with electronic balance, to be made into mass percent respectively be 5%, 10%, 15%, 20%, 25% sucrose solution.Splash into centrifuge tube gently since 25% sucrose solution of getting 5ml successively, be mixed with gradient solution.

(3) the carbon nanotube dispersion liquid slowly is added on the gradient liquid.

(4) 4000rpm, horizontal rotor is centrifugal under the 60min condition.

(5) mixed solution after centrifugal is divided into 5 parts, with dropper slow sucking-off from the top.Finally obtain the different carbon nanotube of length.

Separating resulting is referring to Fig. 1,2,3.

Claims

1. A method for separating carbon nanotubes by density gradient method, characterized in that the concrete steps of the method are:

a. Prepare the carbon nanotubes treated with mixed acid into an aqueous solution with a concentration of 0.5-1.5 mg/ml, and disperse them ultrasonically to fully disperse the carbon nanotubes;

b. the sucrose is made into aqueous solutions with mass percentages of 5%, 10%, 15%, 20%, and 25% respectively, and equal-volume solutions are successively prepared into gradient solutions in the order from high concentration to low concentration;

c. Slowly add the dispersion obtained in step a to the gradient solution obtained in step b; the volume ratio of the dispersion to the gradient solution is 1:5;

d. 4000rpm, horizontal rotor centrifugation under the condition of 60min;

e. According to the number of gradient solutions, the centrifuged mixed solution is aliquoted and slowly sucked out; finally, carbon nanotubes with different lengths are obtained;

The carbon nanotubes are multi-walled carbon nanotubes.