Caracterização e estudo da viabilidade na aplicação de adsorventes como amostradores utilizados para coleta de naftaleno e formaldeído

Abstract

Biochar, or biochar, is a material with adsorbent characteristics consisting of fine and porous particles, with high carbon content, relatively high resistance to decomposition, and presence of functional groups in its peripheral structure, producing from the pyrolysis of vegetal biomass. Like the biochar, the clays present fine particles, that is, high surface area, besides presenting high surface load, and high capacity of cation exchange. Therefore, these materials have been investigated for their ability to remove some organic pollutants. In contrast to industrial development, concern about the emission of gaseous pollutants is increasingly present, and consequently there is a growing need for the development of gas samplers, such as formaldehyde and naphthalene. In this work the possible use of these adsorbent materials (biochar, clay and activated biochar) as naphthalene and formaldehyde samplers, characterized them by infrared spectrometry (FTIR) and electron scanning microscopy (SEM), and analyzing the washing effect of these materials and their adsorption via spectrophotometry in the ultraviolet-visible region. Biochar was produced from castor bean pyrolysis, and its use is seen as an alternative to the disposal of this solid residue. The activation of the biochar was carried out with solution of nitric acid heated in reflux system. The clay in turn is an organophilic and hydrophobic clay. Despite the adsorption of the compounds of interest, no analytical method was found to allow them to be used as samplers. The washes of the materials made it impossible to use them for naphthalene sampling, since they exhibited absorption of wavelength close to or equal to that of the compound of interest. The use of the biochar as a formaldehyde sampler was evaluated, but it was not possible to perform the desorption of the analyte, which would make it unfeasible to use it as a sampler. However, the use of activated biochar, despite having better adsorption results and higher porosity, did not present desorption using the viable solvent for chromotropic acid analysis. Infrared biochar and clay spectra presented the presence of some organic groups and the scanning electron microscopy images allowed to observe an increase of the pores when compared the biochar with the activated biochar and some morphological differences between the analyzed materials.