|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.