Chelating polymeric membranes

Abstract

The present application offers a solution to the current problems associated with recovery and recycling of precious metals such as gold and copper from scrap material, discarded articles, and other items. The solution is premised on a microporous chelating polymeric membrane comprising a poly-thiosemicarbazide formed from N,N′-diaminopiperazine and a suitable reactant such as diisothiocyanate; the membrane may be formed through the use of a solvent system and non-solvent system. The membrane may be used to separate metal ions from solutions and incorporated in a membrane module.

What is claimed is: 
     
         1 . A membrane module for selective recovery of a metal ion comprising:
 a casing having flanges which support and sealingly close ends of the casing;   an inlet opening configured to couple with an inlet conduit for introducing a feed into the casing;   an outlet opening configured to couple with an outlet conduit for removing a filtrate from the casing; and   a membrane cell defined by the casing and comprising a microporous polymeric body, wherein the polymer has the following recurring unit:   
       
         
           
           
               
               
           
         
       
       wherein R is a bivalent hydrocarbon radical. 
     
     
         2 . The membrane module of  claim 1 , wherein R comprises an alkanediyl, oxy-alkanediyl, methylene diphenylene, or phenylene. 
     
     
         3 . The membrane module of  claim 2 , wherein the polymer has a weight average molecular weight of about 10,000 to 500,000. 
     
     
         4 . The membrane module of  claim 1 , wherein the polymer comprises the following recurring unit: 
       
         
           
           
               
               
           
         
       
     
     
         5 . The membrane module of  claim 4 , wherein the polymer has a weight average molecular weight of 10,000 to 100,000. 
     
     
         6 . The membrane module of  claim 1 , further comprising an evacuation opening configured to couple with an evacuation conduit for the egress of the filtrate from the casing, wherein the portion of filtrate passing through the evacuation opening has passed through the microporous polymeric body from a first surface of the microporous polymeric body to a second surface of the microporous polymeric body. 
     
     
         7 . The membrane module of  claim 1 , wherein the microporous polymeric body is a plurality of beads or particles. 
     
     
         8 . The membrane module of  claim 7 , wherein the beads or particles have a diameter of 50 to 1000 μm. 
     
     
         9 . The membrane module of  claim 1 , wherein the microporous polymeric body is in the form of a film, sheet, fiber, or hollow fiber. 
     
     
         10 . The membrane module of  claim 9 , wherein the microporous polymeric body is an asymmetric membrane. 
     
     
         11 . The membrane module of  claim 9 , wherein the microporous polymeric body is a film having a thickness of 20 to 1000 μm. 
     
     
         12 . The membrane module of  claim 11 , wherein the film is supported on a non-woven polyester support. 
     
     
         13 . The membrane module of  claim 9 , wherein the membrane cell comprises a plurality of microporous polymeric bodies in the form of hollow fibers bundled longitudinally. 
     
     
         14 . The membrane module of  claim 13 , wherein the hollow fibers extend along the direction of flow. 
     
     
         15 . The membrane module of  claim 9 , wherein the microporous polymeric body is the form of a spirally-rolled sheet having a first spiral end and a second spiral end. 
     
     
         16 . The membrane module of  claim 15 , wherein the first spiral end faces the inlet opening and the second spiral end faces the outlet opening. 
     
     
         17 . The membrane module of  claim 1 , wherein the casing is a pressure vessel. 
     
     
         18 . The membrane module of  claim 17 , wherein the membrane cell is adapted for a pressure difference within the range of 0.5 to 4 bar. 
     
     
         19 . The membrane module of  claim 1 , wherein the casing is a tubular conduit with ends that sealingly close to prevent or minimize leaking of the feed during operation. 
     
     
         20 . The membrane module of  claim 1 , wherein the microporous polymeric body is configured for regeneration and reuse.