Direct formation of gold nanoparticles using ultrasound

Patent metadata

Field	Value
Publication number	US-10500643-B2
Application number	US-201715484856-A
Country	US
Kind code	B2
Filing date	Apr 11, 2017
Priority date	Apr 12, 2016
Publication date	Dec 10, 2019
Grant date	Dec 10, 2019

Abstract

The invention provides a green chemistry, aqueous method to synthesize gold nanoparticles directly from bulk gold sources. The method involves the ultrasonication of bulk gold in water in the presence of an alkythiol species and a quaternary ammonium surfactant. An organic bilayer forms on the surface of the gold which renders it susceptible to material ejection from the violent collapse of cavitation bubbles. This ejected material is stabilized in solution by the formation of an organic bilayer and can be easily separated. It can then be subjected to an aqueous digestive ripening step to give a gold nanoparticle ensemble with a well-defined plasmon resonance. This method is applicable to a number of different sources of bulk gold. The method can be applied to an environmentally important problem; the recovery of gold from electronic waste streams. For example, gold nanoparticles can be extracted directly from the surface of SIM cards, with no prior manipulation of the cards necessary.

First claim

We claim:

1. A method of forming gold nanoparticles, comprising
providing a solid bulk gold in an aqueous solution comprising an alkylthiol and a surfactant that form an organic bilayer on a surface of the solid bulk gold; and
ultrasonicating the aqueous solution to form gold nanoparticles by implosive collapse of cavitation bubbles on the surface of the solid bulk gold.

2. The method of claim 1 , wherein the alkylthiol comprises dodecanethiol.

3. The method of claim 1 , wherein the surfactant comprises a quaternary ammonium salt.

4. The method of claim 3 , wherein the quaternary ammonium salt comprises didodecyldimethylammonium bromide.

5. The method of claim 3 , wherein the quaternary ammonium salt comprises cetyltrimethylammonium bromide or cetyltrimethylammonium chloride.

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

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

8. The method of claim 1 , further comprising digestive ripening of the gold nanoparticles.

9. The method of claim 8 , wherein the digestive ripening comprises refluxing in water in the presence of a ripening agent.

10. The method of claim 9 , wherein the ripening agent comprises poly(ethylene glycol) methyl ether thiol.

11. The method of claim 1 , wherein the solid bulk gold comprises a metallic gold powder.

12. The method of claim 11 , wherein the size of the metallic gold powder is less than 20 μm.

13. The method of claim 1 , wherein the solid bulk gold comprises a gold contact.

14. The method of claim 13 , wherein the gold contact comprises an electronic waste.

15. The method of claim 14 , wherein the electronic waste comprises a cellular subscriber identity module card.

Assignees

• Nat Tech & Eng Solutions Sandia Llc

Inventors

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

Classifications

• B22F2999/00

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

• B22F1/0551

  Flake form nanoparticles · CPC title

• B22F1/054

  Nanosized particles · CPC title

• B22F9/04 Primary

  starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C) · CPC title

• B22F2301/255

  Silver or gold · CPC title