A novel synthesis of NaA zeolite encapsulated iron(III) Schiff base complex: Photocatalytic oxidation of direct blue-1 dye with hydrogen peroxide

The complex of FeIII2[2-(hydroxy-benzeylidine)-amino]benzoic acid has been encapsulated in pores of NaA zeolite by two different synthesis procedures, namely a zeolite synthesis method in the presence of preformed iron complex (FeIIIL/Aen) and a solid–solid-type reaction (FeIIIL/Ass). The preparations were characterized by using powder XRD, mid-FTIR, Mössbauer spectroscopy, TGA/DTGA, sorption and surface texture measurements. These results have been compared with those obtained for neat complex. The carbon and iron percentages obtained by elemental analysis indicate a mononuclear structure of the complex with 1Fe:1L proportion. Analysis by Mössbauer confirmed that FeIII acquires distorted octahedral structure of the encapsulated complex, with a number of iron ions being formed as α-Fe2O3 in FeIIIL/Ass. The compatible physicochemical data of solids have indicated a better complex encapsulation for sample prepared by the zeolite synthesis method. The complex in FeIIIL/Aen serves to impart structural order to the inorganic NaA network where the integrity of the matrix was confirmed by FTIR, XRD and texture studies. The resulting host/guest compound including H2O2/UV is active system for the oxidative color removal of direct blue-1 in aqueous heterogeneous suspensions with very low catalyst/substrate ratio. The heterogenized complex especially FeIIIL/Aen is significantly more stable than the corresponding homogeneous complex over prolonged reaction time, and therefore a better catalyst than the homogeneous one.