Manufacturing process for porous material

Abstract

A method for the manufacture of a solid porous separation material based on a polysaccharide, said method comprising the steps of: (a) providing an aqueous solution (I) of a polysaccharide, (b) solidifying the solution, preferably by transforming the solution to a gel, and (c) optionally cross-linking the polysaccharide, with the proviso that, if step (c) is present, steps (b) and (c) may be carried out simultaneously. The method is characterised in that the polysaccharide provided in step (a) is modified by being inter-molecularly cross-linked to an extent such that the viscosity of solution (I) is at least 110%, preferably at least 200%, of the viscosity of an aqueous solution (II) of the corresponding polysaccharide which has not been inter-molecularly cross-linked and which is present in the same concentration as the inter-molecularly cross-linked polysaccharide is in solution (I).

1 . In a method for the manufacture of a solid porous separation material based on a polysaccharide, including the steps of 
 (a) providing an aqueous solution of a polysaccharide, and    (b) solidifying the solution by cooling to transform the solution to a gel, the improvement comprising modifying the viscosity of the aqueous polysaccharide by cross-linking prior to step (b).    
     
     
         2 . The method of  claim 1 , further comprising a step of cross-linking of the polysaccharide gel of step (b), either simultaneously with, or subsequent to, step (b).  
     
     
         3 . The method of  claim 1 , wherein in step (b), the gel is solidified into the form of beads or a monolith.  
     
     
         4 . The method of  claim 1 , wherein the polysaccharide used in step (a) is water-soluble above a certain temperature and forms a gel at lower temperatures.  
     
     
         5 . The method of  claim 4 , wherein the polysaccharide is selected from the group consisting of dextran, agarose, cellulose, starch and pullulan.  
     
     
         6 . The method of  claim 1 , wherein, prior to step (b), the solution is disintegrated to drops that are transformed to a gel in step (b).  
     
     
         7 . The method of  claim 6 , wherein the disintegration includes forming a suspension in which the polysaccharide solution is the discontinuous phase and an organic solvent the continuous phase.  
     
     
         8 . The method of  claim 6 , wherein the disintegration results in formation of free drops.  
     
     
         9 . The method of  claim 8 , wherein disintegration includes spraying the solution through a nozzle or by atomizing the solution by a spinning disc technique.  
     
     
         10 . The method of of  claim 1 , wherein densifying particles which have a density higher than the solution are dispersed into the solution or coated with the solution before step (b).  
     
     
         11 . The method of  claim 10 , wherein the densifying particles have a density ≧1.5 g/cm 3  such as ≧3 g/cm 3 .  
     
     
         12 . The method of  claim 10 , wherein the densifying particles constitute ≦95% (v/v) of the polysaccharide solution.  
     
     
         13 . (canceled)  
     
     
         14 . The method of  claim 1 , wherein the polysaccharide before step (a), or during or after the subsequent sequence of steps is functionalized with affinity groups.