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ePaper created 2013-09-24, 11:56:35 | version 1.25.20
101 top of Fig. 5 that the synthesized polymers exhibit greatly dif- fering selectivities. The P(VPS-co-MBA) polymer favors the adsorption of neodymium, followed by lead. However, the P(N-ATU-co-MBA) polymer favors the adsorption of silver, fol- lowed by copper. The diagram at the bottom of Fig. 5 shows the adsorption characteristics of sheep’s wool and lignin. It can be seen that after modification the sheep’s wool adsorbs significantly more gold and mercury. Lignin favors the adsorp- tion of gold. To achieve an intensification of the process, adsorption will be combined with a membrane separation in the project. For the polymer P(N-ATU-co-MBA) a so-called polymer-enhanced ultrafiltration (PEUF) was carried out in which a silver solution was filtered by means of a UF. The result of this experiment is shown in Fig. 6. For comparison, the filtration process was carried out once again with the addition of the polymer. The results indicate clearly that due to the addition of the poly- mer (red bar), even when the silver concentration in the solu- tion is increased, more silver was retained by the adsorption on the polymer than compared with the UF membrane (blue bar). The adsorbers are also to be incorporated direct in the membrane. For example, lignin was used in the production of membranes by mixing it directly into an initial polymer solu- tion (Fig. 7). In addition, particles of the polymer adsorbers were also integrated into membranes (Figs. 8, 9). We could demonstrate that the adsorption properties of the polymer materials are preserved when incorporated in the membrane. 7 8 9 6 4 Vinylphosphonic acid, N-allylthiourea, N,N´-methylenebisacrylamide (from top). 5 Results of adsorption experiments to determine selectivity. 6 Polymer-enhanced ultrafiltration (PEUF). 7 Lignin-filled membranes. 8 Polymer nanoparticles carrying phosphonic acid groups on their surface for selective binding of metal ions. 9 Membrane adsorbers filled with functional polymer nanoparticles. » 0 AdsorbedAgcontent[%bywght.] Initial concentration Ag+ 15 ppm 30 ppm 100 80 60 40 20 5 ppm 82.4 % 98.5 % 44.2 % 98.5 % 10 ppm 67.9 % 99.5 % 61.9 % 99.5 % UF membrane (unspecified adsorption) Membrane + polymer P(N-ATU-co-MBA)