1. Department of Inorganic Chemistry, University “Politehnica” of Bucharest, Str. Gh. Polizu nr. 1, Bucharest 011061, Romania; Department of Physical Chemistry, University of Bucharest, Bd. Elisabeta nr. 4-12, Bucharest 030018, Romania; and Department of Environmental Protection and Inorganic Technology, University “Politehnica” of Bucharest, Str. Gh. Polizu nr. 1, Bucharest 011061, Romania