WO2010081268A1

WO2010081268A1 - Methods for separating and redispersing nano-materials

Info

Publication number: WO2010081268A1
Application number: PCT/CN2009/000774
Authority: WO
Inventors: 刘景富; 刘睿; 阴永光; 江桂斌
Original assignee: 中国科学院生态环境研究中心
Priority date: 2008-12-30
Filing date: 2009-07-07
Publication date: 2010-07-22
Also published as: CN101766923B; CN101766923A

Abstract

Methods for separating and redispersing nano-materials include the following steps: adding a kind of nonionic surfactant to an aqueous dispersion solution of nano-materials whose concentration is 10^-6-1 mg/mL to obtain a mixture, the amount of the nonionic surfactant is 0.05-1wt% of the aqueous dispersion solution of nano-materials; heating the mixture at 30℃-60℃ for 5-60 minutes; adding a kind of salt to the mixture and the amount of the salt is 0.01-1wt% of the mixture; separating the mixture into a two-phase system with an upper clear liquid and a lower cloud point phase having said nano-materials by centrifugal separating. In addition, by cooling the separated nano-materials dispersion from 30℃-60℃ to 0℃-20℃, the nano-materials can be redispersed reversibly. The methods are suitable for separating and redispersing nano- materials in the field of nano-materials application.

Description

Method for separation and redispersion of nanomaterials

The present invention relates to a method for separation and redispersion of nanomaterials, and more particularly to a method for separation and redispersion of nanomaterials suitable for nanomaterial applications. Background technique

Many applications of nanomaterials involve the preparation of high concentrations of aqueous solutions or aqueous dispersions of nanomaterials, as well as the enrichment/recovery/separation of nanomaterials from aqueous solutions. Reversible transfer between different phases to achieve their recovery and recycling of precious metal nanomaterials acting as catalysts has a scientific and potential economic value. At present, there are few methods for phase transfer of nanomaterials, mainly including a method for separating micro or nano-sized particles based on a water two-phase system of a buffer solution of a polymer and water or water ((a) SM Baxter, PR Sperry and Z. Fu, Langmuir, 1997, 13, 3948-3952; (b) MR Helfrich, M. El-Kouedi, MR Etherton and CD Keating, Langmuir, 2005, 21, 8478-8486; (c) X. Zeng And K. Osseo-Asare, J. Colloid Interf. Sci., 2004, 272, 298-307) ₀ long-chain thiols, ionic liquids, polymers, surfactants, planar metal compounds can also be used in the phase of nanomaterials Transfer. However, these methods achieve temperature-controlled reversible dispersion and separation by preparing special polymer-metal ion or polymer-metal oxide nanocomposites, or by synthesizing some special chemicals that have not yet been commercialized.

Therefore, it is of great significance to develop a method for the nanomaterials with different chemical compositions and different surface modifications that can be used for low cost and reversible separation and dispersion of nanomaterials. Summary of the invention

It is an object of the present invention to provide a method for the separation and redispersion of nanomaterials which is capable of reversibly separating/redispersing nanomaterials having different chemical compositions and different surface modifications from an aqueous phase, having wide applicability and low cost. the cost of.

The present inventors have completed the present invention through intensive research.

According to one aspect of the invention, a method for separation of nanomaterials is provided, the method comprising the steps of:

(a) to a concentration of 10- ⁶ -1 mg / mL of the aqueous dispersion of nanomaterials added aqueous dispersion of the nanomaterial by a percentage of 0.05 to 1% by weight of nonionic surfactants, To obtain a mixture; (b) heating the mixture at a temperature between 30 ° C and 60 ° C for 5 to 60 minutes;

(c) adding, to the resulting mixture, 0.01-1% by weight of the mixture; and

(d) Centrifugation to separate the mixture into a supernatant and a two-phase system containing the lower cloud point phase of the nanomaterial.

According to another aspect of the present invention, a method for redispersing a nanomaterial is provided, the method comprising the steps of:

(a) to a concentration of 10- ⁶ -1 mg / mL of the aqueous dispersion of nanomaterials added aqueous dispersion of the nanomaterial by a percentage of 0.05 to 1% by weight of nonionic surfactants, To obtain a mixture;

(b) heating the mixture at a temperature of from 30 ° C to 60 ° C for from 5 to 60 minutes;

(c) adding 0.01-1% by weight of the mixture to the obtained mixture;

(d) centrifuging to separate the mixture into a supernatant liquid and a two-phase system containing the lower cloud point phase of the nanomaterial;

(e) cooling the two-phase system of the supernatant and the lower cloud point phase from 30 ° C to 60 ° C to 0 'C-20 'C, so that the supernatant liquid and the lower layer containing the nano material The two phase system of the cloud point phase is remixed.

Compared with the phase transfer method of existing nano materials, the method has the following advantages:

1. Broad applicability: Nanomaterials with different chemical compositions that can be extracted/phase transferred, including semiconductor quantum dots (eg, CdSe/ZnS quantum dots, etc.), metal oxide nanoparticles (eg, Ti0 ₂ nanoparticles, Fe _{3 )} 0 ₄ nanoparticles), precious metal nanoparticles (eg, Ag, Au, Pt, Pd nanoparticles, etc.) and carbon nanomaterials (eg, C ₆ o fullerene, single-walled carbon nanotubes, multi-walled carbon nanotubes, etc.) )Wait;

2. Greenness of the method: It is not necessary to use chemicals that are toxic (such as mercaptan), odor (ammonium salts), expensive or not yet commercialized (Triton TX-114 has good biocompatibility);

3. Reversibility: The separation/concentration/redistribution of nanomaterials can be flexibly achieved by simply changing the temperature within a small range;

4. The method is based on the formation of a non-covalent assembly of nanomaterials and nonionic surfactants without the use of chemical agents containing sulfur, nitrogen and phosphorus atoms so as not to lose active sites on the surface of the nanomaterial.

5. The method can realize the separation of nano materials at a lower temperature and lower centrifugation, saving energy.

6. This method uses salt as a means of phase separation promotion without the use of other methods, such as pH adjustment. detailed description

In the present invention, the term "cloud point phase" means increasing the nano material and the nonionic surface unless otherwise specified. After the temperature of the aqueous dispersion of the active agent and the addition of the salt to the system, a phase enriched in the nonionic surfactant and nanomaterial appears in the lower portion of the aqueous dispersion.

In the present inventors' research, it was found that when a nonionic surfactant is added to an aqueous solution of a nanomaterial, these nonionic surfactants are rapidly adsorbed on the surface of the nanomaterial by a polyethoxy chain, thereby forming Large micelle clusters - nanomaterial composites. When the temperature of the solution is raised to form a cloud point phase, the hydrogen bonding between the polyethoxyl chain of the surfactant on the surface of the nanomaterial and the surrounding water molecules is weakened, and the intermolecular hydrogen bonding is enhanced, so that the micelle is made. The agglomerate-nanomaterial composite agglomerates, so that the hydrated particle size is further increased. However, the Coulomb repulsion caused by the charge on the surface of the nanomaterial allows these complexes to be stabilized in aqueous solution. These electrostatic interactions can be shielded by the addition of salt, so that the surfactant-rich phase from which the nanomaterial is extracted can be obtained by standing at a lower centrifugal force or for a longer period of time.

The present invention provides a method for the separation of nanomaterials, the method comprising the steps of:

(b) heating the mixture at a temperature between 30 ° C and 60 ° C for 5 to 60 minutes;

(c) adding, to the resulting mixture, 0.01-1% by weight of the mixture; and

According to some preferred embodiments of the invention, the nonionic surfactant is selected from the group consisting of Triton TX-114 (polyoxyethylene (8) nonylphenyl ether, available from Acros Oganic, USA), Triton TX-100 ( Polyoxyethylene (10) octyl phenyl ether, purchased from Acros Oganic, USA, PONPE-10 (polyoxyethylene (10) p-isooctyl phenyl ether, purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo Chemical Industry) , Tokyo)), IgepalCO-630 (2-[2-(4-mercaptophenoxy)ethoxy]ethanol, purchased from Alfa Aesar, USA), Genapol X-150 (isotridecyl polyglycol ether) (15 EO), Clariant Chemicals (China) Co., Ltd., Genapol X-80 (isotridecyl polyglycol ether (8 EO), Clariant Chemicals (China) Co., Ltd.), Brij-30 (polyoxygen) Ethylene lauryl ether, purchased from Acros Oganic, USA, Brij-56 (decyl alcohol, cetyl ether, available from Fluka), Brij-97 (polyoxyethylene (10) oleyl ether, purchased from Sigma Aldrich), Pluronic L61 (oxyethylene (2)-oxypropylene (30)-oxyethylene (2) copolymer, available from BASF), Pluronic P105 (oxyethylene (37)-oxygen Ene (56) - polyoxyethylene (37) copolymer, available from BASF Corporation) and the like, wherein preferably Triton TX- 114.

According to certain preferred embodiments, the nanomaterials are nanomaterials having different chemical compositions, different surface modifications, including but not limited to, semiconductor quantum dots (eg, CdSe/ZnS quantum dots, etc.); Rice particles (eg, Ti0 ₂ , Fe ₃ 0 ₄ nanoparticles, etc.); precious metal nanoparticles (eg, Ag, Au, Pt, Pd nanoparticles, etc.); carbon nanomaterials (eg, C ₆ C fullerene, single-walled carbon) Nanotubes, multi-walled carbon nanotubes, etc.);

According to certain preferred embodiments, a salt is added to the mixture of the nanomaterial and the nonionic surfactant to shield the surface charge of the nanomaterial by the salt, thereby promoting the micellar phase and water during centrifugation The separation of phases.

According to certain preferred embodiments, the salt is a water-soluble salt of a Group I element or a Group II element, such as NaCl, LiCK CK CaCl ₂ , MgCl _{2 ,} etc., of which NaCl is preferred.

According to certain preferred embodiments, the salt is used in an amount of from 0.01 to 1% by weight, preferably 0.2% by weight, based on the weight percent of the mixture obtained in the step (b).

The present invention also provides a method for redispersion of a nanomaterial, the method comprising the steps of: adding 0.05 to 1% by weight of the aqueous dispersion to a nonionic surfactant to obtain a mixture;

(c) adding 0.01-1% by weight of the mixture to the obtained mixture;

(d) centrifuging to separate the mixture into a supernatant and a two-phase system containing the lower cloud point phase of the nanomaterial:

(e) cooling the supernatant liquid and the two-phase system containing the lower cloud point phase of the nano material from 30 ° C to 60 ° C to 0 ° C to 20 ° C to make the supernatant liquid and containing Two-phase system remixing of the lower cloud point phase of the nanomaterial

According to some preferred embodiments of the invention, the nonionic surfactant is selected from the group consisting of Triton TX-114 (polyoxyethylene (8) nonylphenyl ether, available from Acros Oganic, USA), Triton TX-100 ( Polyoxyethylene (10) octyl phenyl ether, purchased from Acros Oganic, USA, PONPE-10 (polyoxyethylene (10) p-isooctyl phenyl ether, purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo Chemical Industry) , Tokyo)) IgepalCO-630 (2-[2-(4-mercaptophenoxy)ethoxy]ethanol, purchased from Alfa Aesar, USA), Genapol X-150 (isotridecyl polyglycol ether) 15 EO), Clariant Chemicals (China) Co., Ltd., Genapol X-80 (isotridecyl polyglycol ether (8 EO), Clariant Chemicals (China) Co., Ltd.), Brij-30 (polyoxyethylene) Dodecyl ether, purchased from Acros Oganic, USA, Brij-56 (decahamol hexadecyl ether, available from Fluka), Brij-97 (polyoxyethylene (10) oleyl ether, purchased from Sigma Aldrich), Pluronic L61 (oxyethylene (2)-oxypropylene (30)-oxyethylene (2) copolymer, available from BASF), Pluronic P105 (oxyethylene (37)-oxypropylene (56)-oxyethylene (37) Copolymer , purchased from BASF Corporation, etc., among which Triton TX-114 is preferred. According to certain preferred embodiments, the nanomaterials are nanomaterials having different chemical compositions, different surface modifications, including, but not limited to, semiconductor quantum dots (eg, CdSe/ZnS quantum dots, etc.); metal oxide nanoparticles ( For example, Ti0 ₂ , Fe ₃ 0 ₄ nanoparticles, etc.; precious metal nanoparticles (eg, Ag, Au, Pt, Pd nanoparticles, etc.); carbon nanomaterials (eg, C _6Q fullerene, single-walled carbon nanotubes, Multi-walled carbon nanotubes, etc.);

According to certain preferred embodiments, the salt is a water-soluble salt of a Group I element or a Group II element, such as NaCl, LiCK KCK CaCl ₂ , MgCl _{2 ,} etc., of which NaCl is preferred.

According to certain preferred embodiments, the salt is used in an amount of from 0.01 to 1% by weight, preferably 0.2% by weight, based on the weight percent of the mixture obtained in the step (b). The invention will now be described in greater detail with reference to the embodiments. It is to be understood that the description and examples are intended to be illustrative and not restrictive. The scope of the invention is defined by the appended claims. Test method: Characterization of separation effect

In the present invention, the effect of separating the nanomaterial by the nonionic surfactant is characterized by calculating the extraction efficiency. The extraction efficiency is calculated by the following methods:

1. For higher concentrations of gold (≥ lmg/L) _: Before and after extraction, the characteristics of nano-gold in the aqueous phase were measured using an ultraviolet-visible spectrophotometer (Model UV-1102, Tianmei Technology, Shanghai). Absorbance value of absorption wavelength A

A, and by calculating the extraction efficiency. In addition, the absorbance value A _{a of the} lower layer of the cloud point phase at the corresponding wavelength can be measured, and 八 / 八 ^ is taken as the enrichment factor C. By CxV _{a A} ^ xl00% (wherein, _¾ cloud point phase volume, of the aqueous phase before extraction volume), the extraction efficiency can be obtained. The extraction efficiency in the method of the present invention is the average of the extraction efficiencies calculated by the above two methods.

2. For lower concentration of gold (≤1 (^ ₈ ) and other nanomaterials (such as Ti0 ₂ , Fe ₃ 0 ₄ , Ag, Pt, Pd nanoparticles, etc.): Inductively coupled plasma mass spectrometry (ICP) -MS) (Agilent 7500ce, Agilent, USA) separately measured the supernatant and the cloud point phase of the mixture after centrifugation, corresponding to the characteristic elements of the nanomaterial used (eg, gold, Au, Fe ₃ 0 ₄ nm) The content of the particles Fe, or the nano-silver Ag, etc., d and C ₂ , and the extraction efficiency is calculated by the following formula:

χΙΟΟ %

Among them, V! and V ₂ are the volumes of the supernatant and the cloud point phase, respectively. Example

The materials used in the examples are as follows:

Triton TX-114 (available from Acros Oganic, USA);

Triton TX-100 (available from Acros Oganic, USA);

PONPE-10 (purchased from Tokyo Chemical Industry, Tokyo);

Polyvinylpyrrolidone (PVP) (purchased from Acros Oganic, USA);

Chloroauric acid (purchased from Sinopharm Chemical Reagent Co., Ltd.);

NaCK KCK AgN0 ₃ , sodium hypophosphite, sodium metaphosphate, FeCl ₃ '6H ₂ 0, FeS (V7H ₂ 0, ammonia (25%), trisodium citrate (purchased from Beijing Chemical Plant);

C ₆₀ fullerene (purchased from Aldrich);

Humic acid (purchased from Acrose Organic, USA);

Ti0 ₂ nanoparticles (AEROXIDE® Ti02 P 25 , purchased from Degussa (China) Co., Ltd.);

CdSe/ZnS/PEG (polyethylene glycol-coated CdSe/ZnS core-shell quantum dots with a particle size of 5-10 nm, purchased from Wuhan Jiayuan Quantum Dot);

Other reagents are from Beijing Chemical Plant. Example 1 : Synthesis of nanosilver

The PVP-coated nanosilver was synthesized by the method of reducing silver nitrate by sodium hypophosphite. The synthesis was carried out as follows: 0.44 g of sodium hypophosphite, 0.4 g of PVP and 0.2 g of sodium metaphosphate were dissolved in 50 mL of secondary water. The pH of the solution was adjusted to 2.0 to obtain solution A. Solution B was obtained by dissolving 1.6 g of silver nitrate in another 10 mL of secondary water. After the solution A and the solution B were simultaneously heated to 40 ° C and held for 30 minutes, the solution B was added dropwise to the solution A under stirring. The obtained mixture was continuously stirred in a 40 ° C water bath for 30 minutes. The obtained nanosilver colloid was centrifuged at 6000 rpm for 20 minutes, and the obtained precipitate was washed once with each of 1% aqueous 1,1,3-benzotriazole, acetone and ethanol to remove unreacted materials. Finally, the reactant was vacuum dried at 50 ° C for 3 hours to obtain a PVP-coated nanosilver powder. The PVP-coated nanosilver was characterized by a transmission electron microscope (TEM) (H-7500, Hitachi, Japan) with an average particle size of 35.8 ± 8.0 nm. Example 2: Synthesis of nano gold (Au ¹ ) with an average particle size of 4.2 ± 1.5 nm

50 mL of 1 mmol/L chloroauric acid solution containing 0.1% Triton X-114 was placed in a 50 mL Erlenmeyer flask and stirred in an ice bath for 30 minutes, after which 1 mL of 100 mmol/L KBH ₄ aqueous solution was added, and Quickly stopper the stopper. After the solution was stirred for 2 hours, nano gold having an average particle diameter of 4.2 ± 1.5 nm as measured by TEM was obtained. Example 3: Synthesis of nano gold (Au ² ) with an average particle size of 13.7 ± 2.4 nm

In a 250 mL Erlenmeyer flask, add 100 mL of 1 mmol L aqueous solution of chloroauric acid and heat to boiling under magnetic stirring. After 30 minutes, 10 mL of 38.8 mmol/L trisodium citrate was added, and the color of the solution changed from light yellow to colorless, black, and finally to wine red, indicating the synthesis of nano gold. The synthesized nano gold was characterized by TEM. The measured gold nanoparticles had an average particle size of 13.7 ± 2.4 nm. Example 4: Synthesis of Nano Gold (Au ³ ) with an Average Particle Size of 40.6 ± 7.9 nm

Nanogold was prepared in the same manner as in Example 3 except that 100 mL of a 2.5 mmol/L aqueous solution of chloroauric acid was added and 2.5 mmol of trisodium citrate was added. The average particle size of the synthesized nano gold is 40.6 ± 7.9

Example 5: Synthesis of gold nanoclusters with an average particle size of 1.5 ± 0.3 nm

1.5 nm gold nanoclusters were synthesized using standard PVP encapsulation. That is, 1.111 g of polyvinylpyrrolidone was added to 100 mL of a 1 mmol/L aqueous solution of chloroauric acid in a 250 mL Erlenmeyer flask. The conical flask was then placed in an ice bath with magnetic stirring. After stirring for 30 minutes, 10 mL of 100 mmol/L potassium borohydride was added to the solution. The color of the solution quickly changed from light yellow to brownish red, indicating the synthesis of nanogold. The average particle size of the synthesized gold nanoparticles is 1.5 ± 0.3 nm. Example 6: Synthesis of nanopalladium

0.0177 g of palladium chloride was added to 100 mL of secondary water and 0.2 mL of 1 mol L of aqueous hydrochloric acid was added. After the dispersion was vigorously stirred at room temperature for 0.5 hour, palladium chloride was dissolved and the solution turned bright yellow. Then add 1 mL of 100 mmol/L aqueous KBH ₄ solution and quickly stopper the stopper. After stirring the solution for 2 hours, nanopalladium having an average particle diameter of 3.6 ± 1.0 nm as measured by TEM was obtained. Example 7: Synthesis of nanoplatinum

Nanoplatinum was prepared in the same manner as in Example 2 except that chloroauric acid was replaced with chloroplatinic acid. Prepared The average particle size of rice palladium is 8.6 ± 2.9 nm. Example 8: Humic acid-coated Fe ₃ 0 ₄ nanoparticles

Dissolve 6.1 g of FeCl ₃ -6H ₂ 0 and 4.2 g of FeS0 ₄ 7H ₂ 0 in 100 mL of secondary water and heat to 90 V, then add 10 mL of 25% ammonia and 50 mL containing 0.5 under rapid stirring. An aqueous solution of humic acid. The resulting mixture was stirred at 90 ° C for 30 minutes and then cooled to room temperature. The obtained black precipitate was filtered and rinsed using a secondary water, drying can be obtained humic wrapped Fe ₃ 0 ₄ nanoparticles. The Fe ₃ 0 ₄ nanoparticles obtained had an average particle diameter of 9.3 ± 3.3 nm. Example 9: Synthesis of nanometer copper oxide

Add 50 mL of 20 mmol/L copper sulfate solution to 50 mL of 40 mmol/L NaOH in ethanol. The copper oxide ethanol sol was obtained by refluxing the solution under stirring for 2 hours. It was freeze-dried under vacuum at -52 ° C to obtain a powdery solid. The powdery solid is redissolved in water to obtain a nano-copper aqueous solution having an average particle diameter of 61.5 ± 13.4 nm. Example 10: Dispersion of C _6Q fullerene

The fullerene was dissolved in toluene to prepare a solution having a concentration of lg/L. Add 20 mL of lg/L fullerene in toluene solution to 50 mL of secondary water and add 1.5 mL of ethanol. The resulting mixture was subjected to ultrasonication in an ultrasonic cleaner (Crest Model 275HT, 38.5 KHZ, USA) to remove the organic solvent, thereby obtaining a stable aqueous dispersion of C ₆ o fullerene. Example 11: Separation and redispersion of nanosilver

To a solution of 9.5 mL of 0.01 mg/mL of the nanosilver (average particle diameter: 35.8 ± 8.0 nm) prepared in Example 1, 0.4 mL of a 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to 9.9 mL with distilled water. After the obtained solution was heated in a water bath at 35 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano silver-rich cloud point phase. The extraction efficiency of nanosilver measured by ICP-MS was 97%.

Then, the two-phase system of the supernatant and the lower cloud point phase was placed in an ice bath for 5 minutes, and after shaking, a nano-silver redispersion was obtained. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a nano-silver-rich cloud point phase again. Heavy After 10 cycles of this cycle, the average particle size of the nanosilver measured by TEM was 34.5 ± 11.4 nm, and no significant change occurred. Example 12: Separation and redispersion of gold nanoparticles (Au ² )

To 8.9 mL of 0.01 mg/mL aqueous solution of gold (Au ² ) (13.7 ± 2.4 nm) prepared in Example 3, 1.0 mL of 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to 9.9 mL with distilled water. After the resulting solution was heated in a 35 ° C water bath for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ² )-rich cloud point phase. The extraction efficiency of nano gold (Au ² ) measured by an ultraviolet-visible spectrophotometer was 99%.

Then, the temperature of the two-phase system of the supernatant and the lower cloud point phase is lowered to 0 ° C, and a redispersion of gold (Au ² ) is obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 C and then centrifuged at 160 g for 10 minutes to again obtain a nano-gold (Au ² ) rich cloud phase. After repeating this cycle 10 times, the average particle diameter of the nano gold (Au ² ) measured by TEM was 13.3 ± 2.5 nm, and no significant change occurred. Example 13: Separation and redispersion of gold nanoparticles (Au ² )

To a solution of 9.5 mL of 0.01 mg/mL of gold (Au ² ) (13.7 ± 2.4 nm) prepared in Example 3, 0.4 mL of 50 mg/mL PONPE-10 aqueous solution was added, and the volume was adjusted to 9.9 mL with distilled water. The resulting solution is at 35

After heating in a water bath at ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ² )-rich cloud point phase. Nano gold measured by UV-Vis spectrophotometer

The extraction efficiency of (Au ² ) was 92%.

Then, the temperature of the two-phase system of the supernatant liquid and the lower cloud point phase is lowered to 4'C, and a red gold (Au ² ) redispersion liquid is obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 C and then centrifuged at 160 g for 10 minutes to again obtain a nano-gold (Au ² ) rich cloud phase. After repeating this cycle 10 times, the average particle diameter of the nano gold (Au ² ) measured by TEM was 13.3 ± 2.1 nm, and no significant change occurred. Example 14: Separation and redispersion of gold nanoparticles (Au ¹ )

Add 0.4 mL of 50 mg/mL Triton X-100 aqueous solution to 9.5 mL O.Ol mg/mL aqueous solution of gold (Au') (4.2 ± 1.5 nm) prepared in Example 2, and dilute to 9.9 mL with distilled water. . The resulting solution was at 60 ° C After heating in a water bath for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ¹ )-rich cloud point phase. The extraction efficiency of nano gold (Au ¹ ) measured by an ultraviolet-visible spectrophotometer was 93%.

Then, the temperature of the two-phase system of the supernatant liquid and the lower cloud point phase was lowered to 4 ° C, and a redispersion of nano gold (Au ¹ ) was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The redispersion was again heated to 60 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ¹ ) rich cloud phase. After repeating this cycle 10 times, the average particle diameter of the nano gold (Au ¹ ) measured by TEM was 4.6 ± 1.3 nm, and no significant change occurred. Example 15: Separation and redispersion of gold nanoparticles (Au ¹ )

Add 0.4 mL of 50 mg/mL Triton X-114 aqueous solution to 9.5 mL of O. 1 mg/mL aqueous solution of gold (Α^) (4.2 ± 1.5 nm) prepared in Example 2, and dilute to 9.9 mL with distilled water. . After the resulting solution was heated in a water bath at 60 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ¹ )-rich cloud point phase. The extraction efficiency of nano gold (Au ¹ ) measured by an ultraviolet-visible spectrophotometer was 97%.

Then, the temperature of the two-phase system of the supernatant and the lower cloud point phase is lowered to 0'C, and a redispersion of nano gold (Au ¹ ) is obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The redispersion was again heated to 60 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ¹ ) rich cloud phase. After repeating this cycle 10 times, the average particle diameter of the nano gold (Au ¹ ) measured by TEM was 4.6 ± 1.3 nm, and no significant change occurred. I - Example 16: Separation and redispersion of gold nanoparticles (Au ³ )

To a solution of 9.5 mL of 0.01 mg/mL of gold (Au ³ ) (40.6 ± 7.9 nm) prepared in Example 4, 0.4 mL of a 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to 9.9 mL with distilled water. After the resulting solution was heated in a water bath at 35 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L KC1 aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nano-gold (Au ³ )-rich cloud point phase. The extraction efficiency of nano gold (Au ³ ) measured by an ultraviolet-visible spectrophotometer was 93%.

Then, the temperature of the two-phase system of the supernatant and the lower cloud point phase was lowered to 12 ° C, and a redispersion of gold (Au ¹ ) was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. Re-dispersing the redispersion to 60 ° C, followed by centrifugation at 160 g for 10 minutes, can again obtain the nano-gold (Au ¹ ) rich cloud point Phase. After repeating this cycle 10 times, the average particle diameter of the gold (Au ³ ) measured by TEM was 38.6 ± 1.9 nm, and no significant change occurred. Example 17: Separation and redispersion of nanopalladium

To 9.5 mL of O.Ol mg/mL of the aqueous solution of nanopalladium (average particle size: 3.6 ± 1.0 nm) prepared in Example 6, 0.4 mL of 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted with distilled water. To 9.9 mL. After the obtained solution was heated in a water bath at 35 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nanopalladium-rich cloud point phase. The extraction efficiency of nanopalladium measured by ICP-MS was 96%.

Then, the two-phase system of the supernatant and the lower cloud point phase was placed in an ice bath for 5 minutes, and a redispersion of nanopalladium was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a nanopalladium-rich cloud point phase again. After repeating this cycle 10 times, the average particle diameter of nanopalladium measured by TEM was 4.1 ± 1.3 nm, and no significant change occurred. Example 18: Separation and redispersion of nanoplatinum

To 9.5 mL of O.Ol mg/mL of the aqueous solution of nanoplatinum (average particle size: 8.6 ± 2.9 nm) prepared in Example 7, 0.4 mL of 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to 9.9 with distilled water. mL. After the resulting solution was heated in a water bath at 35 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a nanoplatinum-rich cloud point phase. The extraction efficiency of nanoplatinum as measured by ICP-MS was 98%.

Then, the two-phase system of the supernatant and the lower cloud point phase was placed in an ice bath for 5 minutes, and a redispersed solution of nanoplatinum was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a nano-platinum-rich cloud point phase again. After repeating this cycle 10 times, the average particle diameter of nano-platinum measured by TEM was 9.2 ± 2.3 nm, and no significant change occurred. Example 19: Separation and redispersion of humic acid-coated Fe ₃ 0 ₄ nanoparticles

To 9.5 mL of 0.01 mg/mL of the humic acid-coated Fe ₃ 0 ₄ nanoparticle (average particle size: 9.3 ± 3.3 nm) prepared in Example 8, 0.4 mL 50 mg/mL Triton X-114 was added. Aqueous solution, constant volume with distilled water To 9.9 mL. After the obtained solution was heated in a 35 ° C water bath for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a humic acid-enriched Fe ₃ 0 ₄ nanoparticle. Cloud point phase. The extraction efficiency of the humic acid-coated Fe ₃ 0 ₄ nanoparticles measured by ICP-MS was 97%.

Then, the supernatant liquid two-phase system and the lower cloud point phase placed in an ice bath for 5 minutes, to obtain the oscillation humic wrapped Fe ₃ 0 ₄ particles was redispersed nanometers. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to again obtain the cloud point phase of the humic acid-enriched Fe ₃ 0 ₄ nanoparticles. After repeating this cycle 10 times, the average particle size of the humic acid-coated Fe ₃ 0 ₄ nanoparticles measured by TEM was 9.3 ± 4.4 nm, and no significant change occurred. Example 20: Separation and redispersion of nano-copper oxide

To 9.5 mL of 0.01 mg/mL of the aqueous solution of nano-copper oxide (average particle size: 61.5 soil 13.4 nm) prepared in Example 9, 0.4 mL of 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to 9.9 mL with distilled water. . After the obtained solution was heated in a water bath at 35 ° C for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a cloud phase phase rich in nano copper oxide. The extraction efficiency of nano-copper oxide measured by ICP-MS was 94%.

Then, the two-phase system of the supernatant and the lower cloud point phase was placed in an ice bath for 5 minutes, and a redispersion of the nano-copper oxide was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a cloud phase phase rich in nano-copper oxide again. After repeating this cycle 10 times, the average particle diameter of the nano-copper oxide measured by TEM was 61 nm, and no significant change occurred. Example 21: Separation and redispersion of C _6Q fullerenes

To 9.5 ml of 0.01 mg/mL of the aqueous solution of C ₆₀ fullerene (average particle size: 112.1 ± 57.0 nm) dispersed in Example 10, 0.4 mL of 50 mg/mL Triton X-114 aqueous solution was added, and the volume was adjusted to the volume with distilled water. 9.9 mL. After the resulting solution was heated in a 35 Torr water bath for 30 minutes, 0.1 mL of a 0.2 mol/L NaCl aqueous solution was added, followed by centrifugation at 160 g for 10 minutes to obtain a cloud point phase rich in C _6D fullerene. The extraction efficiency of C _6D fullerene measured by an ultraviolet-visible spectrophotometer was 92%.

Then, the two-phase system of the supernatant and the lower cloud point phase was placed in an ice bath for 5 minutes, and a redispersed liquid of C ₆₀ fullerene was obtained by shaking. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to again obtain a cloud point phase rich in C ₆ o fullerene. After repeating this cycle 10 times, the average particle diameter of the C _6Q fullerene measured by (transmission electron microscopy) was 108.3 ± 53.7 nm, and no significant change occurred. Example 22: Separation and redispersion of Ti0 ₂ nanoparticles

Add 0.4 mL of 50 mg/mL Triton X-114 aqueous solution to 9.5 ml of 0.01 mg/mL Ti0 ₂ nanoparticles (average particle size: 29.2 ± 12.5 nm) (available from Degussa (China)). , with distilled water to a solution of 9.9 mLo obtained after heating for 30 minutes at 35 ° C in a water bath, was added 0.1 mL 0.2 mol / L NaCl aqueous solution, and then centrifuged for 10 minutes at 160g i.e. enriched in Ti0 ₂ nanoparticles The cloud point phase. The extraction efficiency of Ti0 ₂ nanoparticles measured by ICP-MS was 93%.

Then, the supernatant liquid two-phase system and the lower cloud point phase placed in an ice bath for 5 minutes, to obtain the oscillation Ti0 ₂ nano-particles were redispersed. The redispersion was centrifuged at 3000 g for 10 minutes without obtaining a cloud point phase. The re-dispersion was again heated to 35 ° C, followed by centrifugation at 160 g for 10 minutes to obtain a cloud point phase rich in Ti _{2 2} nanoparticles again. After repeating this cycle 10 times, the average particle diameter of the Ti0 ₂ nanoparticles measured by TEM was 26.4 ± 14.0 nm, and no significant change occurred.

Claims

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A method for separation of nanomaterials, the method comprising the steps of -

(a) Concentration is 10-6-1

The weight percentage of the aqueous dispersion is 0.05-1% of a nonionic surfactant to obtain a mixture;

(b) heating the mixture at a temperature of 30 ° C to 6 (TC) for 5 to 60 minutes;

(c) adding, to the resulting mixture, 0.01-1% by weight of the mixture; and

2. The method according to claim 1, wherein the nonionic surfactant is selected from the group consisting of Triton TX-114, Triton®-100, ΡΟΝΡΕ-10, Igepal CO-630, Genapol®-150, Genapol X-80. , Brij-30, Brij-56, Brij-97, Pluronic L61 or Pluronic P105.

3. The method according to claim 1, wherein the nano material is selected from the group consisting of CdSe/ZnS core-shell structure quantum dots, Fe ₃ 0 ₄ nanoparticles, Ti _{2 2} nanoparticles, silver nanoparticles, gold nanoparticles, palladium nanoparticles Particles, platinum nanoparticles, C _6Q fullerenes, single-walled carbon nanotubes or multi-walled carbon nanotubes.

The method according to claim 1, wherein the salt is selected from a water-soluble salt of a Group I element or a Group II element.

The method according to claim 4, wherein the water-soluble salt of the first main group element or the second main group element is selected from the group consisting of NaCl, LiCl, KC1, CaCl ₂ or MgCl ₂ .

6. A method for redispersion of nanomaterials, the method comprising the steps -

Nonionic surfactants aqueous dispersion of nanomaterials' (a) to a concentration of 10- ⁶ -1 mg / mL was added to the aqueous dispersion of the nanomaterial according to the percentage by weight of 0.05 to 1% To obtain a mixture;

(c) adding 0.01-1% by weight of the mixture to the obtained mixture;

(e) cooling the supernatant liquid and the two-phase system containing the lower cloud point phase of the nano material from 30 ° C to 60 ° C to 0 ° C to 20 ° C to make the supernatant liquid and containing The two-phase system of the lower cloud point phase of the nanomaterial is remixed.

7. The method according to claim 6, wherein the nonionic surfactant is selected from the group consisting of Triton TX-114, Triton TX-100, PONPE-10 IgepalCO-630, Genapol X-150, Genapol X-80 Brij-30, Brij-56, Brij-97, Pluronic L61 or Pluronic P105.

8. The method according to claim 6, wherein the nano material is selected from the group consisting of CdSe/ZnS core-shell structure quantum dots, Fe ₃ 0 ₄ nanoparticles, Ti _{2 2} nanoparticles, silver nanoparticles, gold nanoparticles, palladium nanoparticles Particles, platinum nanoparticles, C ₆ c fullerenes, single-walled carbon nanotubes or multi-walled carbon nanotubes.

The method according to claim 6, wherein the salt is selected from a water-soluble salt of a Group I element or a Group II element.

10. The method according to claim 9, wherein the water-soluble salt of the first main group element or the second main group element is selected from the group consisting of NaCl, LiCl, KC1, CaCl ₂ or MgCl ₂ .