1. Department of Colloid Chemistry, University of Szeged, Aradi Vt. 1, H-6720 Szeged, Hungary, Department of Organic Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary, Research Institute of Chemical and Process Engineering, University of Pannonia, Egyetem u. 10, H-8200 Veszprém, Hungary, and MOL Hungarian Oil and Gas Plc, E&P, New Technologies and R&D, P.O. Box 37, H-6701 Szeged, Hungary