Magnetic activated carbon and the removal of contaminants from a fluid streams

Abstract

Magnetic activated carbon and the removal of contaminants from a fluid stream using the magnetic activated carbon is described. The magnetic activated carbon is preferably magnetic powdered activated carbon and may contain titania. The magnetic activated carbon ( 10 ) may be used to remove contaminants such as mercury from fluid streams including flue gases ( 20 ) from a combustion plant.

1 . A method for removing a contaminant from a fluid stream, comprising contacting the fluid stream with a composite of activated carbon and a magnetic material whereby the contaminant is adsorbed on the magnetized activated carbon, and removing the magnetized activated carbon having the mercury adsorbed thereon from the fluid stream.  
   
   
       2 . The method according to  claim 1 , wherein the contaminant is mercury.  
   
   
       3 . The method according to  claim 1 , wherein the composite further comprises a photocatalyst and further comprising the steps of exposing the photocatalyst to excitation energy to provide hydroxyl radicals on the surface thereof.  
   
   
       4 . The method according to  claim 3 , wherein the photocatalyst is TiO 2 .  
   
   
       5 . The method according to  claim 3 , wherein the photocatalyst is present in the composite in an amount of less than about 10% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       6 . The method according to  claim 5 , wherein the photocatalyst is present in the composite in an amount of less than about 7% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       7 . The method according to  claim 6 , wherein the photocatalyst is present in the composite in an amount of less than about 5% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       8 . The method according to  claim 1 , further comprising the step of recycling the magnetized activated carbon removed from the fluid stream back into contact with the fluid stream.  
   
   
       9 . The method according to  claim 1 , wherein the fluid stream is flue gas from a combustion plant.  
   
   
       10 . The method according to  claim 9 , wherein the combustion plant is a coal combustion plant or a waste combustion plant.  
   
   
       11 . The method according to  claim 1 , wherein the activated carbon is injected into the fluid stream under pressure.  
   
   
       12 . The method of  claim 1 , wherein the activated carbon is powdered activated carbon.  
   
   
       13 . The method of  claim 1 , wherein the magnetic material is selected from the group consisting of magnetite, maghemite, hematite and goethite.  
   
   
       14 . The method according to  claim 1 , wherein the composite contains activated carbon and magnetic material in a weight ratio of less than about 5:1.  
   
   
       15 . The method according to  claim 14 , wherein the composite contains activated carbon and magnetic material in a weight ratio of less than about 4:1.  
   
   
       16 . The method according to  claim 14 , wherein the composite contains carbon and magnetic material in a weight ratio of less than about 3:1.  
   
   
       17 . A composite, comprising activated carbon and a magnetic material.  
   
   
       18 . The composite according to  claim 17 , wherein the activated carbon is powdered activated carbon.  
   
   
       19 . The composite according to  claim 17 , wherein the magnetic material is selected from the group consisting of magnetite, maghemite, hematite and goethite.  
   
   
       20 . The composite according to  claim 17 , further comprising a photocatalyst.  
   
   
       21 . The composite according to  claim 20 , wherein the photocatalyst is selected from the group consisting of TiO 2 , ZnO and SnO 2 .  
   
   
       22 . The composite according to  claim 21 , wherein the photocatalyst is TiO 2 .  
   
   
       23 . The composite according to  claim 20 , wherein the photocatalyst is present in an amount of less than about 10% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       24 . The composite according to  claim 23 , wherein the photocatalyst is present in an amount less than about 7% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       25 . The composite according to  claim 24 , wherein the photocatalyst is present in an amount of less than about 5% by weight based upon the total weight of the photocatalyst and composite of activated carbon and magnetic material.  
   
   
       26 . The composite according to  claim 17 , wherein the composite contains activated carbon and magnetic material in a weight ratio of less than about 5:1.  
   
   
       27 . The composite according to  claim 26 , wherein the composite contains activated carbon and magentic material in a weight ratio of less than about 4:1.  
   
   
       28 . The composite according to  claim 26 , wherein the composite contains activated carbon and magnetic material in a weight ratio of less than about 3:1.