2012|13 Annual Report Fraunhofer IGB

10 0 Increasing the concentration In order to achieve efﬁcient separation of metal ions from low-concentration metal solutions, an adsorption process for concentrating the ions is required. In this project, adsorber materials are being developed that permit the selective ad- sorption of metal ions from aqueous solutions. For this, we are pursuing two different concepts: Adsorbers on polymer basis So as to ﬁnd suitable functional groups for the speciﬁc ad- sorption of metal ions, a screening was carried out with vari- ous functional groups. On the basis of these results polymers were synthesized with the functional groups that demonstrat- ed the best adsorption characteristics with regard to certain metals. Fig. 4 shows examples of two of the monomers used (top, middle) as well as the crosslinker (bottom). Adsorbers from renewable resources Lignin and sheep’s wool were selected as renewable resourc- es. On the one hand, the two classes of substances lignin and keratin already possess a high density of functional groups, on the other they tend to be waste materials and are therefore easily available. These materials were used untreated and also in a modiﬁed state for the adsorption experiments. Fig. 5 shows results of adsorption experiments in which the selectivity of the polymer adsorbers is determined. For this purpose, the adsorbers are brought into contact with an aqueous solution containing various metals of the same mo- lar concentration. It can be seen clearly in the diagram at the ENVIRONMENT H N S NH2 O O N H N H O O OH P 4 5 100 0 Adsorbedmetalcontent[mol-%] P(VPS-co-MBA)- polymer P(N-ATU-co-MBA)- polymer Nd Ag Pb Cu 80 60 40 20 0 Adsorbedmetalcontent[mol-%] Sheep’s wool unmodiﬁed Sheep’s wool modiﬁed Organosolv- lignin unmodiﬁed Organosolv- lignin modiﬁed Au Hg Pd 100 80 60 40 20

2012|13 Annual Report Fraunhofer IGB

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