Estudo de remoção do benzeno, tolueno, p-xileno e o-xileno dissolvidos em água por adsorção em organosílica periódica mesoporoso (PMO).

Abstract

This study evaluates the Periodic Mesopores Organosilicas (PMO) synthesized by co-condensation of 1,4-bis(trietoxysilil)benzene (BTEB) and feniltrietoxysilane (FTE) in different mole fractions, under acidic conditions using triblock copolymer Pluronic P123 as template and in the presence of inorganic salt (KCl), to adsorption of aromatic compounds in aqueous synthetic solution. The molar composition of the synthesis followed the synthesis equation: xFTE :29,58-xBTEB: 1.0 P123: 226.75 KCl: 38HCl: 12583H2O, where x ranged from 0 to 11.83, as designating the solids obtained as PMO1,0; PMO0,8; and PMO0,6, whose index indicates the fraction of BTEB in the composition of the mixture. Structurally, it was observed that incorporation of FTE to process generates PMOs with reduced thermal stability, with lower values of surface area and pore volume and lower hydrophilic character. The measures for small angle of X-ray diffraction, the transmission microscopy and the isotherm of nitrogen adsorption and desorption showed that the products are hexagonally ordered cylindrical pores and has dimensions of meso/macro complementary. The tests for removal of aromatic compounds dissolved in water, the PMO1,0 and PMO0,6 exhibited efficient adsorption capacity of benzene, toluene, p-xylene and o-Xylene (BTXs). In the adsorption experiments with PMO0,6, in batch study, the capacity of removing benzene (0,84 mg.g-1), toluene (0,93 mg.g-1), p-xilene (1,00 mg.g-1) e o-xilene (0,86 mg.g-1) were lower than those obtained in the tests adsorption column: benzene (1,15 mg.g-1), toluene (1,26 mg.g-1), p-xilene (1,25 mg.g-1) e o-xilene (1,15 mg.g-1). The kinetic mechanism of adsorption is primarily identified as pseud-second order and the isotherms can be represented by Redlich-Peterson and Temkin models.