Remoção de amoxicilina usando borra de café como adsorvente

Abstract

The disposal of pharmaceuticals into the environment has been of great environmental concern. With the technological evolution in the techniques of residue analysis in samples has also in-creased the detection and the fear of contamination of effluents. Every day, enormous amounts of antibiotics are consumed and disposed of in the world. All these molecules are discharged into rivers and lakes that may be contaminated. There are several methods available for the removal of organic products from liquid effluents, and adsorption stands out as an excellent alternative for this purpose. The production of soluble coffee by the industry produces a con-siderable amount of organic material with no practical use. Therefore, the carbonaceous resi-dues from the coffee production chain are presented as potential materials for the production of low-cost adsorbents. In this context, this work studied the adsorption of amoxicillin using coffee grounds as adsorbent. For this, the coffee grounds were treated and characterized by XRD, XRF, SEM and thermogravimetry. The adsorption of amoxicillin was evaluated for the effects of pH of the medium (4.0 - 8.0), temperature (27 - 31 ºC), stirring speed (10 - 250 rpm). The results showed that for pH 7.0, 100 rpm stirring and temperature of 27°C, the antibiotic showed the highest adsorption yields. In addition, measuring the nonlinear fits to determine Langmuir, Redlich-Peterson and Freundlich isotherms, the results were satisfactory and consistent. Equi-librium tests were performed to analyze the adsorption kinetics of amoxicillin on coffee grounds. Langmuir, Freundlich and Redlich-Peterson isotherm models were tested. The best fits occurred for the Freundlich model, because this isotherm best fits non-ideal systems, with heterogeneous surfaces where adsorption occurs in multi-layers and for non-uniform surfaces being applied to the case in question. Finally, the results indicated that the adsorption conditions studied presented a great potential to solve the contamination of industrial effluents by amoxi-cillin and that the use of coffee grounds is an excellent adsorbent for this treatment.