Direct formation of metal nanoparticles using ultrasound

Patent metadata

Field	Value
Publication number	US-10518330-B2
Application number	US-201816219482-A
Country	US
Kind code	B2
Filing date	Dec 13, 2018
Priority date	Apr 12, 2016
Publication date	Dec 31, 2019
Grant date	Dec 31, 2019

Abstract

A method for creating nanoparticles directly from bulk metal by applying ultrasound to the surface in the presence of a two-part surfactant system. Implosive collapse of cavitation bubbles near the bulk metal surface generates powerful microjets, leading to material ejection. This liberated material is captured and stabilized by a surfactant bilayer in the form of nanoparticles. Nanoparticles can be produced regardless of the bulk metal form factor. The method is generally applicable of metals and alloys. The method can be applied to an environmentally important problem, the reclamation of gold from an electronic waste stream.

First claim

We claim:

1. A method of forming metal nanoparticles, comprising
providing a bulk metal in a solution comprising a self-assembled monolayer-forming surfactant and an emulsion-forming surfactant that form an organic bilayer on a surface of the bulk metal in a solvent; and
ultrasonicating the solution to form metal nanoparticles by implosive collapse of cavitation bubbles on the surface of the bulk metal and which are stabilized in the solution by the organic bilayer.

2. The method of claim 1 , wherein the self-assembled monolayer-forming surfactant comprises a straight-chained alkyl thiol.

3. The method of claim 2 , wherein the straight-chained alkyl thiol comprises dodecanethiol, 1-octanethiol, or 1-decanethiol.

4. The method of claim 1 , wherein the emulsion-forming surfactant comprises a quaternary ammonium salt.

5. The method of claim 4 , wherein the quaternary ammonium salt comprises didodecyldimethylammonium bromide, cetyltrimethylammonium bromide, or cetyltrimethylammonium chloride.

6. The method of claim 1 , wherein the solvent comprises water.

7. The method of claim 1 , wherein the ultrasonicating uses an ultrasound frequency between 20 kHz and 10 MHz.

8. The method of claim 1 , wherein the metal nanoparticles are less than 100 nm in size.

9. The method of claim 1 , further comprising digestive ripening of the metal nanoparticles.

10. The method of claim 9 , wherein the digestive ripening comprises refluxing in water in the presence of a ripening agent.

11. The method of claim 10 , wherein the ripening agent comprises poly(ethylene glycol) methyl ether thiol.

12. The method of claim 1 , wherein the metal comprises a transition metal or alloys thereof.

13. The method of claim 12 , wherein the transition metal comprises nickel.

14. The method of claim 12 , wherein the transition metal comprises a coinage metal.

15. The method of claim 14 , wherein the coinage metal comprises gold, silver, or gold-silver alloy.

16. The method of claim 1 , wherein the bulk metal comprises metal powder.

17. The method of claim 16 , wherein the size of the metal powder is less than 20 μm.

18. The method of claim 1 , wherein the bulk metal comprises a gold contact.

19. The method of claim 18 , wherein the gold contact comprises an electronic waste.

Assignees

• Nat Tech & Eng Solutions Sandia Llc

Inventors

• Huber Dale L
• Watt John Daniel
• Chavez Jonathan
• Ammerman Lauren Marie

Classifications

• B22F1/054

  Nanosized particles · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• B22F2009/001

  from scrap particles · CPC title

• B22F2999/00

  Aspects linked to processes or compositions used in powder metallurgy · CPC title

• B22F2304/054

  Particle size between 1 and 100 nm · CPC title