Vol. 115 (2009) ACTA PHYSICA POLONICA A No. 4 Proceedings of the Tenth Annual Conference of the Materials Research Society of Serbia, September 2008 Synthesis, Characterization and Application of Al,Fe-Pillared Clays P. Bankovi ´ c * , A. Milutinovi ´ c-Nikoli ´ c, N. Jovi ´ c-Jovi ˇ ci ´ c, J. Dostani ´ c, ˇ Z. ˇ Cupi ´ c, D. Lon ˇ carevi ´ c and D. Jovanovi ´ c Institute of Chemistry, Technology and Metallurgy, University of Belgrade Department of Catalysis and Chemical Engineering, Njegoˇ seva 12, 11000 Belgrade, Serbia Al,Fe-pillared clay was synthesized from domestic clay from Bogovina according to a common procedure: grinding, sieving, Na exchange, pillaring, drying and calcination. Two synthesized samples differing only in calcining conditions were prepared. Phase composition and textural properties of the starting clay and synthesized pillared clays were characterized using X-ray diffraction and physisorption of nitrogen. Catalytic tests were performed using sample with better textural properties being the one submitted to milder calcining conditions. Catalytic wet peroxide oxidative degradation of aromatic compounds phenol and tartrazine on the synthesized catalyst was confirmed showing better efficiency in the case of tartrazine. PACS numbers: 61.05.C-, 61.43.Gt, 61.46.-w, 68.43.-h, 82.65.+r 1. Introduction Pillaring is a process of smectite modification used to obtain materials that have found a wide range of ap- plications in catalytic, adsorption and separation pro- cesses. Common procedure for pillared clay (PILC) preparation is: swelling of smectite in water, exchange of the interlayer cations by partially hydrated polymeric or oligomeric metal cation complexes in the interlamellar region of the starting clay, drying and calcining of wet cake formed of expanded clay in order to have the metal polyoxocations transformed into metal oxide pillars [1]. One of the most promising solutions for the elimi- nation of pollutants from waste waters is catalytic wet peroxide oxidation (CWPO) using pillared clays. It has been proven as a method extremely effective under mild conditions for the degradation of organic pollutants par- tially or completely transforming them to CO 2 [2–4]. Moreover, hydrogen peroxide is a desirable environment friendly oxidizing agent since it is nontoxic and does not form any harmful by-products. The aim of the research presented in this work was to apply PILCs as catalysts in the CWPO of organic pollutants with goal of finding appropriate solutions for the environmental protection. The efficiency of CWPO is highly influenced by the properties of applied PILC catalyst. PILC properties are affected by various synthesis parameters such as solid– liquid ratio, clay origin, particle size, type of oligomeric * corresponding author; e-mail: predragb@nanosys.ihtm.bg.ac.rs metal cation or mixture of cations, intercalation condi- tions, temperature and duration of calcining etc. In this work the pillaring process was performed on 2 μm frac- tion of Bogovina-originated smectite clay. PILC catalysts based on Al PILC with Fe 3+ as active cation were syn- thesized where several synthesis parameters were main- tained constant such as clay size and origin, type of pil- laring cations and their ratio, cation/clay ratio etc. On the other hand, two extreme calcining sets of parameters found in literature [5, 6] were applied and their influence on the catalyst properties was investigated. Among the two obtained catalysts the one with better textural prop- erties was tested in the CWPO degradation of phenol and food dye tartrazine (presented in Fig. 1). Fig. 1. Structural formula of tartrazine. 2. Experimental Starting material was domestic clay from Bogovina [7, 8]. The 2 μm fraction of this clay with cation exchange capacity (estimated by ammonium acetate method) of 765 mmol kg −1 was used in further experiments and de- noted as raw clay. After transforming the original dom- inantly Ca form of smectite into its corresponding Na (811)