Remoção de contaminantes da indústria do petróleo por adsorção com paligorsquita: uma avaliação cinética e termodinâmica

Abstract

Palygorskite (Pal) is a low-cost clay mineral material and was investigated in this study as a novel adsorbent to study the contaminants removal process from the petroleum industry by the adsorption process. This clay mineral was characterized by X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analysis (TG/DTG/DSC), zeta potential (Ϛ) and N2 adsorption/desorption isotherm analyses by BET and BJH methods. Palygorskite textural properties (specific surface area 156 m2 .g-1 , total pore volume 0.36 cm3 .g1 ) and specific surface chemistry activity with several metals, as Fe2+, Mg2+ and Al3+ according to XRF analysis, were crucial to efficient contaminants adsorption. This material was used in raw and modified forms to evaluate the adsorption capacity. Several kinetic, as pseudo-first order, pseudo-second order, Elovich, intraparticle diffusion and Boyd diffusion; equilibrium as Langmuir, Freundlich, Temkin and Dubinin-Radushkevish isotherms; and thermodynamics (ΔH°, ΔGº e ΔS°) models were used to assess the experimental data. The results showed high correlation to the pseudo-second order kinetic model for the adsorbates (R2 > 0.99), suggesting a chemisorption process as the determining step. Isotherm data were used to evaluate the equilibrium experimental data, which permits to obtain maximum adsorption capacity calculated from the Langmuir isotherm (R2 > 0.97), where it can be observed that Pal presents an improved in the dye removal capacity (14.285 mg.g-1). The Pal adsorbent showed good adsorption potential, standing out for being an abundant clay mineral in nature, environmentally safe, and with high possibility of its applications in adsorption and catalysis processes.