Cobalt imprinted polymer composition for selective removal of cobalt, process for preparation thereof, and process for removal of cobalt

Abstract

The present invention provides a polymer composition for the selective removal of cobalt, a process for the preparation thereof and the process for removal of cobalt, using the said polymer composition. More particularly it relates to a cross-linked polymer composition prepared by the molecular imprinting technique. The preparation of the cross linked polymer involves selection of vinyl monomers bearing functional groups that bind to cobalt, formation of a complex of these monomers with cobalt and subsequent polymerization of the complex in presence of a crosslinker. The process for the removal of cobalt comprises treating the solution containing a mixture of cobalt and other metal ions with the polymer under conditions sufficient for cobalt to form a complex with the polymer and separating the polymer from the cobalt depleted solution.

1 . A cobalt imprinted polymer composition useful for the selective removal of cobalt, having general formula (1)  
         A (x)  B (y)  C (z)  D (f)    (1)  
       wherein A is any vinyl monomer containing hydroxyl group, B is any vinyl monomer bearing acidic group, C is any vinyl monomer containing an amino group and D is a cross linker bearing vinyl group and x, y, z and f are the mole fractions of A, B, C and D respectively in the final polymer and vary such that 0<x, y, z<1 and f can vary between 0 and 1 and x+y+z+f=1.  
     
     
         2 . A process for the preparation of the polymeric composition (1)  
         A (x)  B (y)  C (z)  D (f)    (1)  
       wherein A is any vinyl monomer containing hydroxyl group, B is any vinyl monomer bearing acidic group, C is any vinyl monomer containing an amino group and D is a cross linker bearing vinyl group and x, y, z and f are the mole fractions of A, B, C and D respectively in the final polymer and vary such that 0<x, y, z<1 and f can vary between 0 and 1 and x+y+z+f=1, said process comprising preparing a complex of monomers A, B, and C bearing the functional groups, and a source of cobalt in a solvent, adding a cross linker D, porogen and a free radical initiator to this mixture, polymerizing the mixture to obtain a cobalt imprinted polymer, extracting cobalt from the cobalt imprinted polymer to obtain the final polymer composition.  
     
     
         3 . A process as claimed in  claim 2  wherein the monomer (A) is selected from the group consisting of 2-hydroxy ethyl methacrylate, 2-hydroxy propyl methacrylate, N-methacryloyl serine and p-styrene phenol.  
     
     
         4 . A process as claimed in  claim 2  wherein the monomer (B) is selected from the group consisting of N-(4-vinyl benzyl) iminodiacetic acid, acrylic acid, methacrylic acid, N-methacryloyl aspartic acid, N-methacryloyl glutamic acid, Acrylamido methane sulfonic acid, p-vinyl benzoic acid and 2-acetamidoacrylic acid.  
     
     
         5 . A process as claimed in  claim 2  wherein the monomer (C) is selected from the group consisting of N-vinyl imidazole, N-methacryloyl histidine, 4(5) vinyl imidazole, 4-vinyl pyridine and p-amino styrene.  
     
     
         6 . A process as claimed in  claim 2  wherein the crosslinker (D) is selected from the group consisting of ethylene glycol dimethacrylate, triethylene glycol, dimethacrylate, divinyl benzene, trimethylol propane trimethacrylate, N,N′ bis acrylamide, and trimethylol propane acrylate, glycerol dimethacrylate, bisphenol A dimethacrylate and bisphenol A diacrylate.  
     
     
         7 . A process as claimed in  claim 2  wherein the free radical initiator is selected from the group consisting of azobisisobutyronitrile, t-butyl hydroperoxide and benzoyl peroxide.  
     
     
         8 . A process as claimed in  claim 2  wherein the source of cobalt is a salt of cobalt selected from the group consisting of cobalt nitrate, cobalt chloride and cobalt acetate.  
     
     
         9 . A process as claimed in  claim 2  wherein the solvent is a lower aliphatic alcohol.  
     
     
         10 . A process as claimed in  claim 2  wherein the porogen is a higher aliphatic alcohol selected from dodecanol, hexanol and octanol.  
     
     
         11 . A process for the removal of cobalt from the mixture of metal ions using the polymeric composition of formula (1)  
         A (x)  B (y)  C (z)  D (f)    (1)  
       wherein A is any vinyl monomer containing hydroxyl group, B is any vinyl monomer bearing acidic group, C is any vinyl monomer containing an amino group and D is a cross linker bearing vinyl group and x, y, z and f are the mole fractions of A, B, C and D respectively in the final polymer and vary such that 0<x, y, z<1 and f can vary between 0 and 1 and x+y+z+f=1,which comprises contacting a mixture containing cobalt metal ions with a polymeric composition of formula (1) to form a cobalt complex with the polymer, separating the cobalt complex polymer by conventional methods to obtain the mixture devoid of cobalt.  
     
     
         12 . A process as claimed in  claim 11  wherein the metal ion mixture has a pH in the range of 2 to 6.  
     
     
         13 . A process as claimed in  claim 11  wherein the quantity of the polymeric composition (1) is 1000 times by wt of that of the cobalt metal ion concentration in the mixture.