Application of Langmuir and Freundlich models in the study of banana peel as bioadsorbent of copper (II) in aqueous medium

Abstract

Contamination of water by heavy metals is still a major risk of pollution. Considering this scenario, adsorp-tive processes and various adsorbent materials have been used for decontamination. Among the synthetic materials and bioadsorbents used, the synthetics are efficient in the removal of metals in aqueous solution, however they add a high cost compared to bioadsorbents. The bioadsorbents are generally derived from agroindustrial biomass and have been noted for being abundant, renewable and cost-effective for the remedi-ation of effluents with heavy metals in the ionized form. Among the bioadsorbents, the banana peel contains functional groups capable of adsorbing heavy metal ions in aqueous medium. Thus, this work describes the method of preparation and characterization of the banana peel flour through the techniques of Scanning Elec-tron Microscopy (SEM), Dispersive Energy of x-ray (EDX) and Fourier Transform Infrared Spectroscopy (FT-IR), as well as studies of the adsorptive capacity of this bioadsorbent for the Cu (II) ion in aqueous solu-tions. The adsorption studies were carried out by evaluating experimental adsorption isotherms as a function of contact time, pH, temperature and Cu (II) ion concentration in the solution by batch technique. The experimental isotherms were submitted to the mathematical models of Langmuir and Freundlich isotherms. The maximum adsorption capacity achieved by the FCB was 15.1 mg of Cu (II) per gram of FCB, adjusted pH at 5 and very fast saturation time, around 10 minutes. The Langmuir isotherm was the model that best fitted the copper (II) adsorptive process by FCB and the filling of the active sites was around 98.7%.