Gleichgewicht und Kinetik der Sorption von Schwermetallionen an reinem und polymermodifiziertem Goethit

Abstract

The thesis deals with the reaction of the heavy-metal ions Pb"2"+, Cd"2"+ and Ni"2"+ with pure goethite as well as with polymethacrylic acid (PMA) modified goethite. Subject of investigations are the charging behaviour of the oxide goethite, the equilibrium and the chemical kinetics. The results obtained are interpreted by means of two surface complexation models. Potentiometric titrations of goethite at different ionic strengths have shown that in the pH range between 3.0 and 6.0 the surface is positively charged. The charging behaviour is described quantitatively well by the triple layer model (TLM). All pH-dependent adsorption isotherms of Pb"2"+, Cd"2"+ and Ni"2"+ on goethite at constant ionic strength show the same S-shape course. Due to the increased screening of charge with increasing ionic strength the adsorbed amount of heavy-metal ions on goethite also rises. Lead ions - in general - show a higher affinity to goethite than cadmium and nickel ions. (orig.)Available from TIB Hannover: RA 831(3802) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman