Adsorção de ácido 2,4-diclorofenoxiacético em carvão ativado granular de resíduos de buriti (mauritia flexuosa l.): estudo em batelada e leito fixo. Orientador: Lênio José Guerreiro de Faria. 2024. 135 f.

Abstract

Pesticides, when applied responsibly, are essential for agricultural productivity, however, depending on their dosage or frequency of exposure, they can cause numerous problems for human health, in addition to the contamination of soil and surface or underground water. Following this problem, this manuscript aimed to evaluate the adsorption of the herbicide 2,4- dichlorophenoxyacetic acid (2,4-D) using physically activated granular carbon (CAT) and chemically activated granular carbon with ZnCl2 (CAQ) produced from the endocarp and endosperm of buriti (Mauritia flexuosa L.), typical fruit from the Amazon region. The adsorbents were characterized in terms their textural and physicochemical properties through the percentage of ash, moisture, specific surface area (SBET), pore volume (Vtotal), by SEM/EDS, XRD, FTIR spectroscopy, TGA/DTA, the surface functional groups, point of zero charge (pHPCZ) and the surface pH of the carbon. Batch adsorption tests were carried out to elucidate the influence of activated carbon dosage and the effect of solution pH. The adsorption mechanisms and the nature of the process were investigated by studying the kinetics, equilibrium and thermodynamics for the coal with the highest performance. The best results for adsorbate removal percentage were CAT (96.93%) and CAQ (92.46%) and the adsorption capacity CAT (29.00 mg.g-1 ) and CAQ (137.70 mg.g -1 ) within 24 hours, pH 2.0 and dosage of 0.25 g of CAT and 0.05 g of CAQ. The CAQ adsorbent showed superior results in removal and adsorption capacity, with its kinetics fitting the pseudo-second order model, with external diffusion being the determining stage of the adsorption process. The isotherms were satisfactorily fitted to the Sips model. The thermodynamic data revealed the endothermic, physical and spontaneous nature of the adsorption process. The adsorption on fixed bed confirmed that the adsorvent mass, concentration of solution and the inlet flow were influent in the adsorption process, highlighting the efficiency of simultaneous optimization tecnic, within the experimental region explored in this work. Both interactions showed that the charcoals produced present high yield, with the development of pores and surface groups, and excellent performance in removing the 2,4-D herbicide, promising substitutes for commercial carbons.