RESUMO
In this study, silica and functionalized silica materials (3-aminopropyl and 3-mercapto derivatives) were successfully used for the removal of the pesticides bentazone and imazapyc from aqueous solutions. Adsorbent materials were characterized by BET isotherms and FT-IR spectroscopy (confirming the functionalization), and their equilibrium adsorption capacity was evaluated at different ionic strengths. It is observed that the maximum adsorption capacities decrease in the order 3-aminopropyl-derivative > silica >3-mercaptopropyl derivative. An increase in ionic strength produces an enhancement in the removal of pesticides. All isotherms are Ib-type and follow the Langmuir model, suggesting a monolayer physical adsorption process.
Assuntos
Dióxido de Silício , Poluentes Químicos da Água , Adsorção , Benzotiadiazinas , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier , ÁguaRESUMO
In this study, commercial activated carbons (GAB and CBP) were successfully used for the removal of two phenoxy acetic class-herbicides, 4-chloro-2-methyl phenoxy acetic acid and 2.4-dichlorophenoxy acetic acid (MCPA and 2.4-D) from aqueous solution. The adsorbent materials were characterized, and their equilibrium adsorption capacity was evaluated. The results suggest that the microporous properties of GAB activated carbon enhanced the adsorption capacity, in comparison to CBP carbon. Thus, the increasing in the ionic strength favored the adsorption removal of both pesticides, indicating that electrostatic interactions between the pollutant and the adsorbate surface are governing the adsorption mechanism, but increasing pH values decreased adsorption capacity. Experimental data for equilibrium was analyzed by two models: Langmuir and Freundlich. Finally, computational simulation studies were used to explore both the geometry and energy of the pesticides adsorption.