Adsorção do antibiótico sulfametoxazol em carvão ativado

Abstract

Contamination by several pollutants, including emerging pollutants, has led to the development of advanced technologies for sewage treatment and treatment for water supply. These pollutants cause environmental contamination and, as they do not have proven ecotoxicological effects, are not regulated by law; and thus, they are not monitored. An example of a group included in this category are drugs, widely used for human and veterinary use. Among these drugs, sulfamethoxazole is an antibiotic belonging to the sulfonamide family, commonly prescribed for the treatment of urinary infections, pneumonia, chronic bronchitis, meningococcal meningitis and toxoplasmosis. Thus, this work had the objective of analyzing the adsorptive potential of the activated carbon in the removal of the sulfamethoxazole drug in aqueous solution. For this purpose, the pH variables and the activated carbon mass were optimized through a complete 22 factorial experimental design with central points for an initial survey, later adjusted and the experimental design was applied central rotational compound 2² with central points and axial, its effect on the adsorptive process was evaluated. The statistical evaluation was based on analysis of variance and the study of the lack of adjustment. Subsequently, the adsorption tests were carried out, evaluating the kinetics, isotherms and thermodynamics of the process. Optimization by the desirability function indicated that the ideal conditions for the process were mass equal to 0.023 g of activated carbon and pH equal to 5.6, with a removal percentage of 73.8%. The contact time to reach the equilibrium of the process is 360 minutes, reaching an efficiency of 92.17% removing 4.53 mg.g-1. The experimental data were adapted to the kinetic model of pseudo-first order. For the adsorption isotherms, the Langmuir model best described the experimental data, indicating removal efficiencies between 96 and 98%, reaching maximum adsorption capacities were 39.67, 54.23 and 51.91 mg.g-1 for temperatures of 25, 35 and 45°C. The thermodynamic parameters indicated that the biosorption process is spontaneous, favorable and endothermic. Thus, activated carbon showed a favorable performance for sulfamethoxazole removal.