Adsorção De Fármacos A Partir Do Resíduo Da Casca Da Acácia-Negra (Acácia Mearnsii De Wild) Moído, Tratado E Transformado Em Carvão Ativado

Abstract

One of the polluting sources from unwatered or not properly treated disposal is domestic sewage, which contains numerous residues of compounds that are used daily by the population. Among the various existing methods for the treatment of effluents that serve to complement the conventional treatment, adsorption stands out, where the solid surface used as an adsorbent can be either synthetic or of natural origin. Given this scenario, this work aimed to use the residue of black wattle bark used in the extraction of tannin, which generates around 70% of residue, as an adsorbent medium and raw material for the production of activated carbon for the removal of nimesulide. , an anti-inflammatory widely used by the population mainly because it is not necessary to use an average prescription. The material was ground, dried, impregnated with H3PO4 and followed by pyrolysis in an inert atmosphere of nitrogen to produce activated carbon. The adsorbents were characterized in terms of their specific mass, porosity, particle diameter, specific surface area (BET) and immediate analysis of moisture, ash, volatiles and fixed carbon. TGA and XRD analyzes were also performed, which showed that the adsorbents had a reduction in crystallinity and decomposition of hemicellulose after chemical and thermal treatments. The surface area of the coal produced was 153.4 m²/g and the particle diameter was 149.28 µm. The carbon produced was analyzed under two different conditions for the removal of nimesulide, where the kinetic results for both the model that best fit was the pseudo second order, reaching equilibrium in 10 min when using an adsorbent dose of 0. 5g/L and an initial concentration of 35 ppm of nimesulide (condition 1 defined by preliminary tests). For a dosage of 0.1g/L of adsorbent and a concentration of 50ppm of nimesulide (condition 2 defined through an experimental design) equilibrium was reached in 45 min. The isotherm that best described the first condition was the Langmuir model reaching a maximum adsorption capacity of 518.20 mg/g and the Sips model for the second condition with a maximum adsorption capacity of 4382.3 mg/g. In the continuous adsorption analyses, in a fixed bed, the carbon produced was saturated in approximately 7h and obtained a fixed bed adsorption capacity of 674.04 mg/g. The parameters used in the second condition, defined through an experimental design 2³, showed that studying the main variables of influence in the adsorption process and their respective effects, before the analysis, is of great importance to improve the conditions of the adsorption process and thus achieving a higher maximum adsorption capacity. From the results obtained, it is possible to state that the performance of activated carbon produced from black wattle bark residues has positive results and has the potential to be applied as an adsorbent in the treatment of water contaminated with nimesulide.