ANÁLISE DAS VARIÁVEIS QUE INFLUENCIAM A ADSORÇÃO DA IVERMECTINA MEDIANTE CASCA DE BOCAIÚVA (Acrocomia aculeata) E MODELAGEM DO PROCESSO

Abstract

The advent of new substances, as well as new patterns of consumption, have grown with technological advances. The use of drugs increased in the last decades, and some effluent treatment plants no longer can withhold them, with may lead to resistant pathogenic organisms and fauna and flora endocrinological desregulation, especially ivermectin, a broadly used anthelmintic for both humans and animals since the 1980s. Its removal from effluents can be done by adsorption, a simple process when done in batches and economically advantageous and sustainable if used raw agroindustrial waste. Acrocomia aculeata epicarp is a residue from food, medical, cosmetic and fuel industries, and the palm fruit is present in South America’s savanna regions. The objective of this work is to access if the epicarp is a valid adsorbent in the process to remove ivermectin from aqueous solutions, and to evaluate the the process through experimental central composite design in order to take into account the effects of temperature, pH and adsorbent mass onto the efficiency and adsorbed amount of the batch adsorption. The adsorbent was characterized by its point of zero charge, 4,96; by FTIR and UV-Vis spectra; by SEM and TGA, which all have displayed behavior coherent with literature. The experimental design provided surface responses in which temperature and mass (both linear and quadratic equation terms) were statistically relevant, as well as the interation between pH and mass, and the pH for the adsorbed amount only, and the model adjustment obtained were 0,85 for both dependent variables. The method provided optimal conditions with the tool “desirability” as 40 °C, pH 9,0 and 0,3 g, resulting in 97,997% of removal and 5,92 mgadsorbate/gadsorbent adsorbed. The isotherm model that best fitted the experimental data was the Freudlich model, with R² = 0,94, and the kinects were better described by Elovich model, with R² = 0,997. The epicarp of Acrocomia aculeata proved to be an efficient adsorbent to remove ivermectin from aqueous solutions.