Adsorption analisys of tio2 prepared by pechini method

ADSORPTION ANALISYS OF TiO2 PREPARED BY PECHINI METHOD
P. C. Ribeiro*, D. A.Vieira, A. C. F. M. Costa, L. Gama and H. L. Lira
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Departament of Materials Engineering, Federal University of Campina Grande, Campina Grande, PB, Brazil

Titanium dioxide (TiO2) is a semiconductor which is found in three different crystalline structures, anatase (tetragonal), rutile (tetragonal) and brookite (orthorhombic). The TiO2 is a material used in several applications, such as: biomaterials, pigment, optical device, electronics, membranes and photocatalyst to remove organic pollutants, thus numerous researches in the chemical synthesis of this material has been done. Among these methods the Pechini technique outstands. The aim of this work is to characterize the TiO2 prepared by Pechini method by nitrogen adsorption. The powder was prepared with citric acid/metallic cations proportion of 1:1 and 7:1. From the isotherms gas adsorption of TiO2 it was possible to obtain the textural characteristics of the powder. The estimation of surface area and adsorption/desorption isotherms of the sample was done by BET method. This technique is also used to estimate the particle size by using the equation proposed by Reed [2]. Figure 1 show the adsorption/desorption isotherms of TiO2. It can be observed that TiO2 powders present mesopores with diameter between 2 and 50nm and isothermal type V, with hysteresis type II based on IUPAC classification. It can be also observed that the sample 1:1 and 7:1 present good value of surface area (47.49 and 43.94 m2/g, respectively) and this can give the preparation of particles with 30 and 32nm of size, respectively. The results confirms that the Pechini method is promissory to the TiO2 mesoporous preparation, with nanometric particle size and the increase in citric acid/metallic cations can reduce the surface area and consequently increase the particle size.
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60 Volume adsorbed (cc/gSTP) 50 40 30 20 10 0,0 0,2 0,4 0,6 P/Po 0,8 1,0 Sample 1:1