Adsorção de diclofenaco comercial por subprodutos da indústria de papel e celulose

Abstract

Medicines such as diclofenac are emerging pollutants that can have bioaccumulative and bioreactive characteristics, found in industrial or domestic effluents, and therefore have a high capacity to contaminate water bodies. The adsorption technique is being studied and used more frequently to remove these contaminants from effluents. The aim of this study was to evaluate waste from the pulp industry (grits and dregs) as adsorbents for diclofenac. The study was divided into the material characterization and analysis stage and batch adsorption tests. The by-products dregs and grits are composed of various chemical elements, mainly calcium, and have a rough morphology, obtaining PCZ values of pH>12 and 8.68, respectively. In the 2³ experimental factorial planning tests, it was concluded that the best conditions for the adsorbents were 0.5 g mass, pH 7.5 and a concentration of 10 mg.L-1 of DCF for dregs and 1.5 g mass, pH 7.5 and a concentration of 10 mg.L-1 of DCF for grits. The results were adjusted to the pseudo-first, pseudo- second order, Weber and Morris and Elovich kinetic models in which the equilibrium time for dregs was 45 min and for grits was 100 min, in which the adsorption system fitted the kinetic models well. For the isothermal tests, the maximum adsorption capacity for dregs was 54.966 mg.g-1 at 298 K and 51.2702 mg.g-1 at 303 K for grits, in which the system was better suited to both isothermal models with the highest adsorption capacity for dregs, while for grits the system was best suited to the Freundlich model, indicating a greater presence of chemical adsorption. As for thermodynamics, the adsorbents were endothermic, spontaneous, adsorption becomes more efficient with increasing temperature, as does the disorder of the system, however, dregs proved to be less efficient than grits. The studies indicate the enormous potential of dregs and grits materials as adsorbents for diclofenac and even other anionic emerging pollutants due to their good adjustment to the tests, short equilibrium time and satisfactory results in terms of adsorption capacity, as well as being sustainable and accessible materials, making it essential to invest in research into these materials for future application in the market and in industry.