Method of making composite particles with tailored surface characteristics

Abstract

The invention describes a procedure to make metal containing composite particles and composite particle suspensions. The procedure is versatile and can produce particles with a variety of particle sizes and compositions. For some applications the metal composite particles can provide the functionality of wholly metallic particles including configurations where the metal is located on the particle surface. Such metals have application in a wide variety of fields, including accomplishing electrochemical reduction and catalysis.

1 . A process for creating a composite particle having a size in the range from nanoscale to micrometer, said process comprising: 
 a) forming a composition comprising a core material, a metal material and a solvent;    b) mixing said composition until an amount of said metal material is deposited onto a surface of said core material thereby forming a composite particle; and    c) adding a dispersant material to said composition after said metal material is deposited onto a surface of said core material;    wherein said solvent material is selected based upon characteristics comprising flash point temperature, autoignition temperature and viscosity; and    wherein said dispersant material is selected based upon characteristics comprising estimated hydrophile-lipophile balance and solvent system compatability.    
   
   
       2 . The process according to  claim 1  wherein the core material is selected from the group consisting of oxide ceramics, non-oxide ceramics, phosphates, sulfates, carbonates, clays, minerals, polymers, plastics, intermetallic compounds, metals, metal alloys and combinations thereof.  
   
   
       3 . The process according to  claim 1  wherein the metal material is selected form the group consisting of Li, Al, Na, K, Si, Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Pd, Ag, In, Sn, Sb, Cs, Ba, La, Ta, W, Pt, Au, Pb, Bi, Ce, and U and alloys and combinations thereof.  
   
   
       4 . The process according to  claim 3  wherein said metal is zero valent.  
   
   
       5 . The process according to  claim 1  wherein the solvent material is selected based upon further characteristics selected from the group consisting of pH, NFPA flammability rating, NFPA health rating, degree of biodegradability, degree of toxicity, degree of miscibility, NFPA reactivity rating and combinations thereof.  
   
   
       6 . The process according to  claim 1  wherein the solvent material has a flash point temperature of greater than about 75° C.  
   
   
       7 . The process according to  claim 1  wherein the solvent material has an autoignition temperature of greater than about 150° C.  
   
   
       8 . The process according to  claim 1  wherein the solvent material has an NFPA flammability rating of ≦1.  
   
   
       9 . The process according to  claim 1  wherein the solvent material has a viscosity of less than about 100 centipoise.  
   
   
       10 . The process according to  claim 1  wherein the solvent material has an NFPA health rating ≦1.  
   
   
       11 . The process according to  claim 1  wherein the solvent material has an NFPA reactivity rating of ≦1.  
   
   
       12 . The process according to  claim 1  wherein the solvent is selected from the group consisting of glycols, glycol ethers, vegetable oils and combinations thereof.  
   
   
       13 . The process according to  claim 1  wherein the dispersant material is selected from the group consisting of anionic, cationic, amphoteric, nonionic and combinations thereof.  
   
   
       14 . The process according to  claim 13  wherein the dispersant material has a hydrophile-lipophile balance of ≦10.  
   
   
       15 . The process according to  claim 14  wherein the dispersant is Disperbyk® 180.  
   
   
       16 . The process according to  claim 1  wherein the core material, metal material and solvent composition is in the range from about 10 to about 60 volume percent powder fraction.  
   
   
       17 . The process according to  claim 1  wherein the composition comprises additional materials.  
   
   
       18 . The process according to  claim 17  wherein additional materials are added to the composition after adding the dispersant material.  
   
   
       19 . The process according to  claim 17  wherein the additional materials are selected from the group consisting of metals, non-metals and micronutrients.  
   
   
       20 . The process according to  claim 19  wherein the additional materials are selected from the group consisting of Pd, Pt, Au, Cu, Ni and combinations thereof.  
   
   
       21 . The process according to  claim 20  wherein the additional materials are introduced to the composition by an electrochemical reaction.  
   
   
       22 . The process according to  claim 1  wherein said core material is added incrementally to the composition.  
   
   
       23 . The process according to  claim 1  wherein the mixing is performed by at least one mechanism selected from the group consisting of milling, ultrasound, lapping and combinations thereof.  
   
   
       24 . The process according to  claim 23  wherein milling is performed with a mill selected from the group consisting of attritor, sand, jar, ball, vibratory and combinations thereof.  
   
   
       25 . The process according to  claim 23  wherein the mixing is performed in modes selected from the group consisting of batch and continuous.  
   
   
       26 . The process according to  claim 1  wherein the mixing is performed from about 1 to about 5 hours.  
   
   
       27 . The process according to  claim 23  wherein the mill is operated at speeds in the range of about 500 to about 3500 rpm.  
   
   
       28 . The process according to  claim 1  further comprising the step of removing metal material after the step of adding the dispersant material.  
   
   
       29 . The process according to  claim 1  further comprising the step of performing an electrochemical reaction with the composition.  
   
   
       30 . The process according to  claim 1  wherein process temperature is maintained between the freezing and boiling points of the solvent material.  
   
   
       31 . The process according to  claim 1  wherein the process is performed in a gas selected from the group consisting of air, nitrogen, oxygen, forming gas and combinations thereof.  
   
   
       32 . The process according to  claim 1  wherein the process is performed in a vacuum.  
   
   
       33 . The process according to  claim 1  wherein the amount of dispersant is in the range from about 0.25 to about 1.50 mg/m 2  total surface area of the composite particle.  
   
   
       34 . A composition comprising 
 a) a composite particle having an inner core material and an outer metal material deposited onto said core material;    b) a solvent; and    c) a dispersant having miscibility in said solvent;    wherein the size of said composite particle is in the range from nanoscale to microscale.    
   
   
       35 . The composition according to  claim 34  wherein the core material is selected from the group consisting of oxide ceramics, non-oxide ceramics, phosphates, sulfates, carbonates, clays, minerals, polymers, plastics, intermetallic compounds, metals, metal alloys and combinations thereof.  
   
   
       36 . The composition according to  claim 34  wherein the metal material is selected form the group consisting of Li, Al, Na, K, Si, Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Pd, Ag, In, Sn, Sb, Cs, Ba, La, Ta, W, Pt, Au, Pb, Bi, Ce, and U and alloys and combinations thereof.  
   
   
       37 . The composition according to  claim 36  wherein said metal is zero valent.  
   
   
       38 . The composition according to  claim 34  wherein the solvent is selected from the group consisting of glycols, glycol ethers, vegetable oils and combinations thereof.  
   
   
       39 . The composition according to  claim 34  wherein the dispersant material is selected from the group consisting of anionic, cationic, amphoteric, nonionic and combinations thereof.  
   
   
       40 . The composition according to  claim 39  wherein the dispersant material has a hydrophile-lipophile balance of ≦10.  
   
   
       41 . The composition according to  claim 34  wherein the dispersant is Disperbyk® 180.  
   
   
       42 . The composition according to  claim 34  wherein the core material, metal material and solvent powder fraction is in the range from about 10 to about 60 volume percent.  
   
   
       43 . The composition according to  claim 34  further comprising materials selected from the group consisting of metals, non-metals and micronutrients.  
   
   
       44 . The composition according to  claim 43  wherein the materials are selected from the group consisting of Pd, Pt, Au, Cu, Ni and combinations thereof.  
   
   
       45 . The composition according to  claim 34  wherein the amount of dispersant is in the range from about 0.25 to about 1.50 mg/m 2  total surface area of the composite particle.  
   
   
       46 . A method for remediation comprising contacting contaminated material with a composite particle made by the process according to  claim 1 .  
   
   
       47 . A method of remediation comprising contacting contaminated material with the composite particle according to  claim 34 .  
   
   
       48 . In a remediation process, the improvement being use of a particle according to  claim 34 .  
   
   
       49 . A composition produced by the process according to  claim 1 .  
   
   
       50 . A process for selecting a dispersant comprising 
 a) forming a particle suspension of about 1 to about 10 mass percent, wherein 
 i) said particle is selected from the group consisting of oxide ceramics, non-oxide ceramics, phosphates, sulfates, carbonates, clays, minerals, polymers, plastics, intermetallic compounds, metals, metal alloys and combinations thereof, and  
 ii) suspending medium is a solvent selected from the group consisting of glycols, glycol ethers, vegetable oils and combinations thereof;  
   b) selecting a candidate dispersant, wherein 
 i) said candidate dispersant is soluble in said solvent; and  
 ii) said dispersant has a hydrophile-lipophile balance of ≦about 10;  
   c) introducing said candidate dispersant in an amount of about 0.0015 to about 0.0045 g/m 2  total particle surface area into said suspension;    d) agitating said suspension; and    e) observing said suspension for evidence of at least one result selected from the group consisting of Tyndall Effect, uniform distribution of particles, and combinations thereof.    
   
   
       51 . The process according to  claim 50  wherein said agitating is performed by ultrasound.