Magnetic filtration process, magnetic filtering material, and methods of forming magnetic filtering material

Abstract

The present invention provides magnetically responsive activated carbon, and a method of forming magnetically responsive activated carbon. The method of forming magnetically responsive activated carbon typically includes providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and increasing pH of the solution to precipitate particles of ferrite that bond to the activated carbon, wherein the activated carbon having the ferrite particles bonded thereto have a positive magnetic susceptibility. The present invention also provides a method of filtering waste water using magnetic activated carbon.

What is claimed: 
     
         1 . A method of forming magnetically responsive activated carbon comprising:
 providing activated carbon in a solution containing ions of ferrite forming elements, wherein at least one of the ferrite forming elements has an oxidation state of +3 and at least a second of the ferrite forming elements has an oxidation state of +2, and   increasing the pH value of the solution to precipitate particles of ferrite having nanoscale dimensions from the ferrite forming elements of the solution onto the activated carbon, wherein the activated carbon having the particles of ferrite attached thereto are magnetically responsive.   
     
     
         2 . The method of  claim 1 , wherein the ratio of the ferrite forming elements having the oxidation state of +3 to the ferrite forming elements having the oxidation state of +2 ranges from approximately 2.5:1 to 1:1. 
     
     
         3 . The method of  claim 1 , wherein the ratio of the ferrite forming elements having the oxidation state of +3 to the ferrite forming elements having the oxidation state of +2 ranges from approximately 2.1:1 to 1.5:1. 
     
     
         4 . The method of  claim 1 , wherein the ratio of the ferrite forming elements having the oxidation state of +3 to the ferrite forming elements having the oxidation state of +2 is 2:1. 
     
     
         5 . The method of  claim 1 , wherein the ferrite forming elements having the oxidation state of +3 are provided by a Fe 3+  salt and the ferrite forming elements having the oxidation state of +2 are provided by a Fe 2+  salt. 
     
     
         6 . The method of  claim 5 , wherein the Fe 3+  salt comprises Fe(NO 3 ) 3  and the Fe 2+  salt comprises FeSO 4 . 
     
     
         7 . The method of  claim 1 , wherein the ferrite particles comprise Fe 2 O 3 , Fe 2 O 3 .CuO, Fe 2 O 3 NiO or (Fe 2 O 3 ) x .(NiO) y , wherein x+y=1. 
     
     
         8 . The method of  claim 1 , wherein the increasing of the pH value comprises adding NH 4 OH, wherein the solution is an aqueous solution. 
     
     
         9 . The method of  claim 8 , wherein the pH value of the solution is increased to within a range of about 10 to about 11. 
     
     
         10 . The method of  claim 1 , wherein the ferrite particles are of nanoscale dimension. 
     
     
         11 . The method of  claim 1 , wherein the ferrite particles have a diameter ranging from about 2 nm to about 250 nm. 
     
     
         12 . The method of  claim 8 , wherein the adding of the NH 4 OH to the aqueous solution containing salts of Fe 3+  and Fe 2+  further produces (NH 4 ) 2 SO 4  and NH 4 NO 3 . 
     
     
         13 . The method of  claim 1 , further comprising heating the solution to a temperature within a range of about 60° C. to about 70° C. 
     
     
         14 . The method of  claim 1 , wherein the activated carbon comprises fibers having a length ranging from about 100 μm to about 1000 μm, and a diameter ranging from about 5 μm to about 30 μm. 
     
     
         15 . The method of  claim 1 , wherein the ferrite particles are present in amounts greater than 1 wt % of the carbon fibers. 
     
     
         16 . The method of  claim 1 , wherein the magnetic properties comprise of a positive magnetic susceptibility. 
     
     
         17 . The method of  claim 1 , wherein the carbon substrate is in the form of a powder, fibers or granules.