1. Chemistry Department, Faculty of Science , Al-Azhar University , Nasr City, P.B. 11884 , Cairo , Egypt
2. Inorganic Chemical Industries and Mineral Resources Division , National Research Centre (NRC) , Giza , Egypt
3. Chemistry Department, Faculty of Science , Al-Azhar University , Nasr City, P.B. 11884 , Cairo , Egypt , Tel.: +(002) 0100 87 53 656, e-mail: