Adsorção de 2,4 D a partir de soluções aquosas em carvão ativado comercial e zeólita natural funcionalizados com surfactantes

Abstract

The presence of pesticides in the environment can cause contamination in various ecosystems, mainly soils and water bodies, contributing to environmental imbalance. The 2,4 D herbicide is the 2nd best-selling pesticide in Brazil, used to control the growth of weeds. Considering the harmful capacity of this compound when in an aqueous environment, technologies are being sought for its removal, and among the possibilities, adsorption stands out. As an objective, the present study sought to investigate the application of activated carbon and zeolite, as well as its functionalization with surfactants, for the treatment of 2,4 D in water, through the determination of adsorption isotherms for low concentrations. After adsorption, the residual 2.4 D in solution was detected by High Performance Liquid Chromatography coupled to the Ultraviolet detector (HPLC-UV). Using a dosage of 10 gads L-1 and starting from an initial concentration of 20 mg L-1, commercial activated carbon was able to adsorb 2.4 D, resulting in values lower than the Maximum Allowed Values stipulated in legislation for water potability. Regarding the maximum adsorption capacity at equilibrium, experimental values were obtained of 1.08 mg g-1 for the natural zeolite clinoptilolite, 0.77 mg g-1 for the zeolite functionalized with Sodium Dodecyl Sulfate (SDS), 1,30 mg g-1 for zeolite with Cetyltrimethylammonium Bromide (CTAB), 11.4 mg g-1 for commercial activated carbon, 3.54 mg g-1 for carbon functionalized with SDS and 3.02 mg g-1 for carbon functionalized with CTAB. Regarding the adjustments to the experimental data, the BET and Langmuir models presented the best adjustments. Among the adsorbent materials studied with and without functionalization, adsorption with activated carbon without functionalization proved to be the best alternative for removing this pollutant from water.