Remoção de Cu2+, Cd2+ e Zn2+ utilizando esferas de sílica funcionalizada com EDTA: estudo em batelada e coluna

Abstract

Inorganic matrices have been used as adsorbent mate rial for removal of chemical pollutants in aquatic systems, due to its good adsorption capacity for physical and chemical stabilities and this work was synthesized silica spheres functionalized with EDTA in order to remove metal ions in aqueous solution . The kinetics of adsorption of the ions under study (Cu2 +, Cd2 + and Zn2 +) was performed at pH 5.5 at a concentration of 60 mg L-1, where it was observed that equilibrium is reached very fast, about 10 minutes, indicating that limiting step of the adsorption process may be the chemisorption, as evidenced by the best fitting model for the pseudo-second order. The adsorption isotherms were subjected to linear and nonlinear model for comparison, using the error function SSE and R2 as a reference. The study of simple and multielement ions was carried out at pH 5.5, concentrations ranging from 10-300 mg L-1, where the data were submitted to the models of Langmuir, Freundlich, Temkin and Redlich-Peterson. The results showed a better fit to the Langmuir model, which argues that the adsorption sites are homogeneous and monolayer adsorption. The maximum sorption capacities observed in studies of equilibrium for the system mono and multielement follow the order Cu2 + > Zn 2 + > Cd2+. For comparison model method was used Akaike's where proved that the Langmuir model is the best. With respect to the study of adsorption column, the breakthrough curves indicate that saturation occurs in the same volume of 35 mL. The use of the eluent 0.1 M HCl, allowed to recover 100% of the adsorbed ions. The column was used for three cycles to verify their potential use, and it was proved that in the three-cycles can recover 100% of the metals, which means an optimum efficiency of the spheres of silica-APTS-EDTA.