Comparative characterization study of a natural zeolite and the same zeolite modified Paloma Vinaches 1 , Hugo M. B. Eustáquio 1 , Vanessa C. de Souza 1 , Sibele B. C. Pergher 1, * 1 Laboratório de Peneiras Moleculares LABPEMOL. Instituto de Química. Universidade Federal de Rio Grande do Norte (UFRN). Campus de Lagoa Nova. CEP: 59078-900. Natal (RN). Brazil. *sibelepergher@gmail.com Introduction Zeolites are crystalline tectosilicates constituted by (SiO 4 ) and (AlO 4 ) tetrahedra connected through the O atoms of their vertices (1). These materials can be found in nature or can be synthesized and they have a wide range of applications including catalyses and adsorption (2). Modified natural zeolites are already applied in metallic cations adsorption like Cu(II), Pb(II) and Mn(II) (3, 4) and are useful in catalysis, for example in photocatalytic degradation of methylene blue (5), heterogeneous catalyse to produce biodiesel from low quality oil (6) and synthesis of various 2- amino-4H-chromene derivatives (7) . The purpose of this work is to study the characterizations of a natural zeolite and the same zeolite modified to increase the knowledge of them, in order to start an evaluation for future works. Experimental Two powder samples of a natural zeolite and this natural zeolite modified were provided for testing for future applications by Celta Brasil company. X-ray diffractograms were obtained in a Bruker D2 Phaser diffractometer from 5º to 45º employing Cu radiation (λ= 1.54 Å) , a Lynxeye detector (192 channels) and 0.02 mm divergent slot. Composition was evaluated by an x-ray fluorescence spectrometry (EDX-720, Rh target). Dynamic thermogravimetric analysis was performed in a Netzsch TG 209F3 equipment in an alumina sample cup under a nitrogen atmosphere from 25°C to 900°C at a velocity of 10°C/min. Results and Discussion Firstly, to know the composition of the samples an x-ray fluorescence spectrometry analysis was performed and results are present in Table 1. A higher quantity of manganese is clearly observed in the composition of the modified natural zeolite. A decrease in the silica, iron oxide and alumina percentage also appeared. Other elements are found in the modified zeolite probably due to process of the modification. Table 1. Composition of the zeolites. Composition (oxide form) Natural Zeolite Modified Natural Zeolite SiO 2 56.1 38.6 Fe 2 O 3 14.1 10.0 Al 2 O 3 12.2 8.0 CaO 5.4 8.5 SrO 3.8 2.3 K 2 O 2.8 2.1 ZrO 2 2.6 1.6 MgO 1.3 0.6 BaO 0.8 0.6 TiO 2 0.6 0.3 MnO 0.1 16.8 CuO 0.1 0.1 ZnO 0.1 0.1 SO 3 - 9.1 Tb 4 O 7 - 1.1 YO 3 - 0.1 Second characterization performed was x-ray diffraction. Resulting diffractograms were analyzed with the Bruker’s program Diffrac-EVA (8) and are shown in Figure 2. Clipnotilolite and mordenite were the main phases identified in the diffactogram. Other phases were difficult to be assigned due to the high quantity of phases mixtured with the most representatives. The crystallinity of the samples was also calculated with the program mentioned: 63% for the natural zeolite and 69% for the modified one. The XRD results complement the characterization by fluorescence. The rationale for the higher levels of manganese oxides found in the modified samples is in the methodology usually applied to modified natural clinoptilolite. Placed in contact with the oxidants potassium permanganate and hydrochloric acid, there is deposition of larger quantities of magnesium oxides on the surface of the zeolitic material (3, 9, 10). These oxides have large surface areas, and high affinity for metal ions, which can lead to think of an efficient route for elimination of pollutants (11).