The synthesis of adsorbents for metal ions in soils and ores

A series of porous copolymer resins with ionogenic or chelating functional groups was prepared from commercial polystyrene or polymethacrylate precursors. Samples of all resins were supplied to Geo2 laboratories for assessment of their efficacy in a proprietary heavy metal remediation process. Two of these resins, DMA-1 and CMS-2, were prepared in bulk to supply pilot scale testing. The crosslinked resin-bead substrates used were: chloromethylated polystyrene (CMS), diethylenetriamine poly(methacrylamide) (DMA), glycidyl methacrylate (GMA), and three types of poly(methyl methacrylate) (MMA, MMB & MMC) with varying degrees of porosity and crosslinking. The alkyl halide moiety of CMS was used to anchor 2° or 3° alkylamines, diethylenetriamine, tris(2-aminoethylamine), or a quaternary ammonium group. Alternatively, a primary amine group was introduced via hydrolysis of hexamethylene tetramine. Poly(ethylene glycol)s of various sizes were affixed to the chloromethylated substrate via Williamson ether synthesis to form \pseudocrown\" ether chains. Benzocrown ether groups were produced by anchoring catechol to the CMS resin and subsequent reaction with acodichloropoly(ethylene glycol). Functional groups on poly(methyl methacrylate) resins were introduced via hydrolysis of the backbone or by aminolysis with tris(2- aminoethyl)amine or 2-aminoethanol. The epoxide moiety of GMA was alkylated with either high-pressure ammonia tris(2-aminoethyl)amine or various grades of poly(ethylene glycol)s. Hydrolysis of the epoxide in aqueous acid was also investigated. Resins with aminocarboxylate moieties were prepared via carboxymethylation of resins with primary amine or diethylenetriamine groups (including DMA) using excess chloroacetic acid in aqueous carbonate solution. The moieties prepared were diethylenetriamine triacetic- and tetraacetic- acids and aminodiacetic acid. Several nonporous pseudocrown ether materials were also produced via copolymerisation yielding urethane or methacrylate substrates. The resins were characterised by elemental analysis and by their Infra-Red spectra. A subset of resins was also characterised by their affinity and capacity to adsorb metal ions in aqueous solution. The sorption of copper from a 75 ppm solution into these resins was measured over a 25 hour period. Adsorption isotherms for Cu 2+ in 0.010 M aqueous hydrochloric acid were also obtained in the range 10-75 ppm. The highest metal capacities were achieved with aminocarboxylate functionalities; amine resins adsorbed very little."