Method for preparing anti-color change nanometer silver colloid

A method for preparing anti-color change nanometer silver colloid, dropping silver nitrate solution into aqueous solution dissolved with the protecting agent and the reducing agent under conditions of 110 to 120 degrees Celsius temperature and 50 to 100 rpm (revolutions per minute) of the stirring speed by adopting a single injecting control flow device so that oxidation reduction reaction is taken place to prepare silver colloid to excellently control the size of nanometer silver particles. Since the method adopts alcohol that has weaker reduction ability as the reducing agent to oxidately reduce with silver nitrate at a high temperature (110 to 120 degrees Celsius), the prepared nanometer silver has excellent anti-color change ability. The obtained nanometer silver is a colorless transparent colloid at the low concentration of 0 to 500mg/kg and a yellow-brown colloid at high concentration. The technique provided in the method is simple and can be easily carried out and produced in large-scale, and the obtai