Sorption of ferrous iron by EPS from the acidophilic bacterium Acidiphilium Sp.: A mechanism proposal

The aim of this work was to assess the uptake of Fe(II) by extracellular polymeric substances (EPS) from the acidophilic bacterium Acidiphillium 3.2Sup(5) . These EPS were extracted using EDTA. EPS of A. 3.2Sup(5) loaded in sorption tests with Fe(II), were characterized using the following experimental techniques: scanning electron microscopy (SEM) with energy dispersive X-ray microanalysis (EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The experimental results indicate that EPS adsorb ferrous iron according to Freundlich model with a metal sorption uptake of K = 1.14 mg 1-1/n L 1/n g -1 and a sorption intensity of 1/ n = 1.26. In addition, ferrous iron sorption by EPS took place by preferential interaction with the carboxyl group which promotes the formation of ferrous iron oxalates (FeC 2 O 4 ). Since the interaction reaction was reversible ( Log K = 0.77 ± 0.33), that means that the cation sorption can be reversed at convenience.