1. Applied and Environmental Chemistry Department, University of Szeged, H-6720 Szeged, Rerrich Bela ter 1, Hungary; Colloid Chemistry Department, University of Szeged, H-6720 Szeged, Aradi Vértanuk tere 1, Hungary; and Nanostructured Materials Research Group of the Hungarian Academy of Sciences, H-6720 Szeged, Aradi Vértanuk tere 1, Hungary