Colloidal solution of silver nanoparticles and method of it preparation

Abstract

The invention relates to colloidal solutions of silver nanoparticles and to method of it preparation and can be used in different areas, particularly in medicine, veterinary science, food industry, cosmetology, household chemistry and agrochemistry. Method includes the electrochemical dissolution of silver in the deionized water. The silver in fine powder form with chemical purity of 99.999% and with nanoparticle sizes up to 100 nm is subjected to electrochemical dissolution in electrolyser, within which are located the electrodes in form of containers made from chemically neutral material, in which fine powder of silver from 100 to 150 g are placed, and by means of conductor covered by chemically neutral coat the direct voltage ranges from 30 to 45 volts is energized. Electrolysis is proceeded under conditions of cycling voltage polarity every 2 hours and mechanical stirring of solution 2 times in twenty-four hours until the concentration of silver in colloidal solution from 5.0 to 100 mg/l. Wherein the portion of silver metal nanoparticles is from 5 to 90% of total concentration of silver in solution, the portion of nanoparticles ranging from 2 to 15 nm is from 65 to 85% of total volume of silver metal nanoparticles in solution, the portion of nanoparticles ranging from 15 to 35 nm is correspondingly from 15 to 35%, the residual portion of total silver concentration in solution is silver ions. The technical result of invention is preparation of the stable colloidal solution of silver nanoparticles.

1 . Method of preparation of colloidal solutions of silver nanoparticles, comprising an electrochemical dissolution of silver in deionized water, characterized in that, silver in fine dispersed powder form with chemical purity of 99.999% and with nanoparticle sizes up to 100 nm is subjected to electrochemical dissolution in electrolyser, comprising housing made from chemically neutral material, within which are located the electrodes in form of containers made from chemically neutral material, in which fine powder of silver from 100 to 150 g are placed, and by means of conductor covered by chemically neutral coat the direct voltage ranges from 30 to 45 volts is energized by means of dc power source under conditions of cycling voltage polarity every 2 hours and mechanical stirring of solution 2 times in twenty-four hours until the concentration of silver in colloidal solution from 5.0 to 100 mg/l, wherein the portion of silver metal nanoparticles is from 5 to 90% of total concentration of silver in solution, the portion of nanoparticles ranging from 2 to 15 nm is from 65 to 85% of total volume of silver metal nanoparticles in solution, the portion of nanoparticles ranging from 15 to 35 nm is correspondingly from 15 to 35%, the residual portion of total silver concentration in solution is silver ions. 
     
     
         2 . The method according to  claim 1 , characterized in that, mechanical stirring of solution is performed by the use of solution contact means made from chemically neutral material. 
     
     
         3 . Method according to  claim 1 , characterized in that, energizing of the voltage on the silver in form of fine powder is performed by the use of conductors covered by chemically neutral coat and passed into electrolyser. 
     
     
         4 . Method according to  claim 1 , characterized in that, additionally filtering of colloidal solution is performed. 
     
     
         5 . Colloidal solution of silver nanoparticles, characterized in that, it comprise deionized water, silver metal nanoparticles and have silver concentration from 5.0 to 100 mg/l, wherein portion of silver metal nanoparticles is from 5 to 90% of total concentration of silver in solution, the portion of nanoparticles ranging from 2 to 15 nm is from 65 to 85% of total volume of silver metal nanoparticles in solution, the portion of nanoparticles ranging from 15 to 35 nm is correspondingly from 15 to 35%, the residual portion of total silver concentration in solution is silver ions. 
     
     
         6 . Colloidal solution of silver nanoparticles according to  claim 5 , characterized in that, it is stable during at least two years.