Desenvolvimento e caracterização de adsorvente de baixo custo para a adsorção de metais pesados em efluentes

Abstract

In this study, the removal of Ni2+, Cu2+, Cd2+ and Zn2+ ions from industrial effluent was investigated using a new adsorbent coconut of Jerivá (Syagrus romanzoffiana). This adsorbent can be used for the removal of toxic metallic ions present in effluents. The surface functionality, morphology, crystallinity, thermal stability and charge of the Syagrus romanzoffiana was studied. The BET and BJH tests were conducted with the objective of knowing the surface area of the studied material, pore volume, pore size distribution and particle irregularity. The Scanning Electron Microscopy (SEM) analysis was performed with the purpose of obtaining the micrographics of the physical structure. The adsorption assays showed that the adsorbent developed has affinity for the studied metals. By adsorption isotherms, the best fit to the experimental data was the Langmuir isotherm (R2 = 0.96) and the highest adsorption capacity was found for Ni2+ followed by Cu2+, Cd2+ and Zn2+. The tests were performed at three different temperatures where the adsorption presented endothermic behavior. This can be attributed to the increase in the number of active sites on the surface of the adsorbent resulting in an increased temperature. The adsorption was energetically favorable (1 <nf <10 and 0 <RL <1). The thermodynamic parameters such as ΔHo, ΔSo and ΔGo have confirmed the favorable to the ions Ni2+, Cd2+ e Zn2+ but not spontaneous endothermic process to Cu2+, and this new adsorbent can be used to remove heavy metals from the water supply. For the multicomponent system, the adsorbent of the Jerivá coconut had an antagonistic effect in the adsorption process with Cu2+, followed by Zn2+ Cd2+ and Ni2+, the order of preference for uptake is justified based on the electronegativity value, hardness/oftness, ionic rays, hydration energy and electronic affinity, etc. of metal ions.