| 摘要 |
PURPOSE: A preparation method of colloidal gold with fine and homogeneous particle size is provided for use in helpful materials to man by dissolving gold into aqua regia and reducing. CONSTITUTION: The preparation method comprises the steps of: dissolving gold into aqua regia by heating at 70deg.C for 6-12hrs., which is represented by the formula, Au + HNO3 + 4HCl -->H(AuCl4) + 2H2O + NO; diluting gold solution by 1/50, 1/50 and 1/10 times, in a first, a second and a third dilution, by adding water; adjusting pH of the gold solution between 10-10.5 and 6.5-7.2 when a reductant is formaldehyde and oxalic acid, respectively; reducing with the reductant, which is represented by the formula, 2HAuCl43H2O + 3HCHO + 11KOH -->2Au + 3HCOOK + 8KCl + 11H2O; and filtering.
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