Method of making and using nanoscale metal

Abstract

The invention provides methods of producing colloids of nanoscale metallic particles particularly useful in the in situ environmental remediation of chlorinated solvents. The methods include ball milling an elemental metal to form a colloid of nanoscale metallic particles having ideal size and metallurgical properties to enhance the reductive dehalogenation of halogenated hydrocarbons.

1 . A method of producing a nanoscale metallic colloid, comprising: 
 suspending an elemental metal in a non-aqueous organic liquid;    adding a dispersant to the suspension; and    ball milling the suspension to form a colloid of nanoscale metallic particles.    
     
     
         2 . The method of  claim 1 , wherein the temperature of the suspension during the ball milling is between about −80° C. and about 100° C.  
     
     
         3 . The method of  claim 1 , wherein the temperature of the suspension during the ball milling is between about −80° C. and about −50° C.  
     
     
         4 . The method of  claim 1 , wherein the temperature of the suspension during the ball milling is between about 20° C. and about 100° C.  
     
     
         5 . The method of  claim 1 , wherein the elemental metal is selected from the group consisting of iron, tin, zinc, palladium, platinum, nickel and combinations thereof.  
     
     
         6 . The method of  claim 1 , wherein particles of the elemental metal being processed have a size in the range of about 1 micron to about 1000 microns.  
     
     
         7 . The method of  claim 1 , wherein the concentration of the elemental metal in the non-aqueous organic liquid is between about 10% wt./vol. and about 80% wt./vol.  
     
     
         8 . The method of  claim 1 , wherein the concentration of the elemental metal in the non-aqueous organic liquid is about 70% wt./vol.  
     
     
         9 . The method of  claim 1 , wherein the concentration of the elemental metal in the non-aqueous organic liquid is about 45% wt./vol.  
     
     
         10 . The method of  claim 1 , wherein the non-aqueous organic liquid is selected from the group consisting of dodecane, ethyl ether acetate, butyl acetate, polypropylene glycol, vegetable oil and mixtures thereof.  
     
     
         11 . The method of  claim 8 , wherein the dispersant has a concentration of between about 1 mg and about 20 mg per square meter of colloid surface area.  
     
     
         12 . The method of  claim 1 , wherein the ball milling is conducted at a rate of between about 10 rpm and about 50 rpm.  
     
     
         13 . The method of  claim 1 , wherein the ball milling is conducted for a time period between about two hours and about 48 hours.  
     
     
         14 . The method of  claim 1 , comprising the additional step of annealing the colloid of nanoscale metallic particles.  
     
     
         15 . The method of  claim 14 , wherein the annealing temperature is between about 200° C. and about 90% of the melting temperature of the metal.  
     
     
         16 . The method of  claim 14 , wherein the annealing is conducted for a period of time between about 2 minutes and about 5 days.  
     
     
         17 . The method of  claim 14 , wherein the annealing comprises at least two heat treatments wherein each heat treatment is conducted at a temperature between about 200° C. and about 90% of the melting temperature of the metal.  
     
     
         18 . The method of  claim 1 , further comprising contacting the colloid with an organic liquid containing a second metal different from the elemental metal of the suspending step.  
     
     
         19 . A method of producing a nanoscale metallic colloid, comprising: 
 suspending an elemental metal selected from the group consisting of iron, tin, zinc, palladium, platinum, nickel and combinations thereof having a particle size in the range of between about 1 micron and 1000 microns in an organic liquid selected from the group consisting of dodecane, butyl ethyl ether acetate, polypropylene glycol, vegetable oil and mixtures thereof,    adding a polymer dispersant with a chain length of 1 to 10 nanometers to the suspension; and,    ball milling the suspension at a rate of about 1,000 rpm for about 6 hours.    
     
     
         20 . A method of producing a nanoscale metallic colloid, comprising: 
 suspending an elemental metal selected from the group consisting of iron, tin, zinc, palladium, platinum, nickel and combinations thereof having a particle size in the range of between about 1 micron and 1000 microns in an organic liquid selected from the group consisting of dodecane, butyl ethyl ether acetate, polypropylene glycol, vegetable oil and mixtures thereof;    adding a polymer dispersant with a chain length of 1 to 10 nanometers to the suspension;    ball milling the suspension; and,    annealing the suspension at a temperature of between about 200° C. and about 90% of the melting temperature of the elemental metal for a time period of between about 2 minutes and about five days.