Abstract
Encapsulation of [Fe(CN)(6)](4-) and [Fe(CN)(6)](3-) complexes in the intracrystalline pores of ZSM-5 zeolite, (FeL)-L-II/Z and (FeL)-L-III/Z respectively, by the zeolite synthesis method was reported. The modified zeolites were characterized by powder XRD, FT-IR and UV-vis spectroscopy. The nitrogen adsorption isotherms allow for the evaluation of pore structure of the complex-modified zeolites, whereas the thermal analysis (TGA/DTA) measurements provide insight into the decomposition products of the immobilized complexes. The modified zeolites exhibited smaller pore volumes and surface areas as compared with those of unpromoted ZSM-5, suggesting the inclusion of iron cyanides inside the interconnecting channels of ZSM-5. While the ferricyanide complex enhanced the formation of highly crystalline zeolite, the ferrocyanide one resulted in a lesser effect. The electronic spectra of the colloidal species developed when (FeL)-L-III/Z brought in contact with an aqueous solution of [Fe(CN)(6)](3-) exhibit absorptions attributed to CN- -> iron charge-transfer. New bands at 294 and 319 nm due to d-d transitions of Fe-III tetrahedral monomeric moieties were emitted concurrently under successive adsorption of [Fe(CN)(6)](aq)(3-) over (FeL)-L-III/Z, along with a broad band at 555 nm assigned to polymeric [Fe-II-C-N-Fe-III] of Prussian blue (PB). The FT-IR spectra of Fe-III/L-III/Z devoted to the adsorption of an aqueous solution of [Fe(CN)(6)](3-) showed a band at 2092 cm(-1) assigned to the C-N stretch in the Fe-II-CN-Fe-III linkages. The vibrations attributable to Fe-O -Si bonding along with hydrocarbon and nitroprusside appeared only in the spectrum of (FeL)-L-III/Z, thus was found to be strong evidence for the mutual interaction between [Fe(CN)(6)](3-) and the latter sample. (C) 2013 Elsevier B.V. All rights reserved.