Thesis (M.Sc.)--Chulalongkorn University, 2011

Gold nanopowders were successfully prepared via a novel green chemistry route. The solution of high concentration of Au³⁺ ion (10,000 ppm) was reduced by sucrose or starch solution in alkaline condition; reducing species were occurred via alkaline degradation of sucrose or starch. The synthesized gold nanoppowders had particles size in the range of nanometer to sub-micrometer (150 – 4,000 nm) as indicated by scanning electron microscope and the complete reduction was investigated by UV-visible spectroscopy. The particle size could be selectively controlled by adjusting concentration of gold ion, concentration of sucrose, and concentration of alkaline. The use of environmentally benign substance like sucrose and starch offer number of benefits such as low production cost, toxic waste reduction, and controllable reaction. This novel route can be easily scaled-up for large-scale production of gold nanopowders.