Effect of Kind of Alcohols as Additives on Preparation of Gold Nanoparticles by Sonochemistry

Abstract

Gold nanoparticles were prepared sonochemically in an aqueous solution containing alcohol as an additive. The effects of the type of alcohol and hydrogen ion concentration on the formation rate of gold nanoparticles were examined. The ultrasound field was provided with a 200 kHz ultrasonic cleaning bath. It was found that the formation rate was controllable by varying the type of alcohol and the hydrogen ion concentration. When lower alcohol such as methanol or ethanol was used, the formation rate of gold nanoparticles at the neutral pH was rapid compared to that in the acidic or alkaline range. At pHs below 8, the formation rate in the presence of higher alcohol such as pentanol or hexanol was faster than that with lower alcohol. When the formation rate was higher, the particle size became smaller under this pH condition. The formation rate at pHs higher than 9.5 using butanol, pentanol or hexanol as an additive, however, was extremely low and the size of gold nanoparticles prepared was very small.