Kinetic modeling of the adsorption and desorption of metallic ions present in effluents using the biosorbent obtained from Syagrus romanzoffiana.

Abstract

In this study, the kinetic mechanism of adsorption and desorption, as well as the equilibrium isotherms, of four metallic ions (Cd2+, Cu2+, Ni2+, and Zn2+) mono and multicomponent were investigated. The biosorbent used was produced from Jerivá (Syagrus romanzoffiana-commonly known as queen palm) coconut. A kinetic model that considers macropore diffusion as a control step was solved. The finite volume method was used in the discretization of the equations, and the algorithm was implemented in the Fortran programming language. The equilibrium time for monocomponent adsorption was 5min; for the multicomponent tests, equilibrium occurred instantly (less than 2min of adsorption). The pseudo-second-order model presented the lowest mean of the sum of normalized errors (SNE) and represented the experimental data of mono and multicomponent adsorption and desorption. Single and multicomponent Langmuir model represented the adsorption isotherms. The maximum capacity of adsorption of metallic ions, both mono and multicomponent, was higher for copper, and the multicomponent adsorption proved to be antagonistic; the presence of co-ions in the solution reduced the removal of metals due to competition between these contaminants. The capture preference order was justified by the physicochemical properties of the ions, such as electron incompatibility and electronegativity. All these situations justified the maximum adsorption of Cu2+, followed by Zn2+, Cd2+, and Ni2+ in the mixture.