Host-Guest Interaction of Iodine with Zeolite A

Josip Bronića*, Lavoslav Sekovanić^b, Ana Mužic^a, Tomislav Biljan^c, Jasminka Kontrec^a and Boris Subotić^a

^aRuđer Bošković Institute, Bijenička 54, 10 000 Zagreb, Croatia
^bGeotechnical Faculty, University of Zagreb, Hallerova aleja 7, 42 000 Varaždin, Croatia
^cFaculty of Science, University of Zagreb, Strossmayerov trg 14, 10 000 Zagreb, Croatia

Absrtract
Introduction of I₂ molecules into zeolite A (sodium form) was made through a three-step procedure: water removal from zeolite, introduction of iodine via gas phase and removal of I₂ from ZA surface by dissolution in absolute ethanol. Interactions of zeolite A saturated with incorporated iodine vapor was studied by vibration spectroscopy (FT Raman and FTIR), DTG and XRD. Results show that about 50% of iodine exists in the framework voids of zeolite A in the form of elemental iodine (molecules, clusters, crystals) and the rest exists in the ionic forms. The ionic forms of iodine (formed by disproportionation of iodine) interact with the negatively charged aluminosilicate framework of zeolite A and with compensating sodium ions. The possible characters of interactions are also discussed.