Effect of pre-treatment and supporting media on Ni(II), Cu(II), Al(III) and Fe(III) sorption by plant root material

In this work Paspalum notatum root material was used to elucidate the influence of acid leaching pre-treatment and of sorption medium on metal adsorption. Ground P. notatum root was leached with 0.14 M HNO3. Leached root material (LRM) and non-leached root material (NLRM) were employed to flow sorption of Ni(II), Cu(II), Al(III) and Fe(III) in 0.5 M CH3COONH4 medium at pH 6.5. For LRM the sorption was also studied in 0.5 M KNO3 medium. The acid pre-treatment increased the sorption capacity (SC) for all ions studied. For the KNO3 medium, Cu(II) and Fe(III) sorption was higher than in CH3COONH4 and the type of the Ni(II) isotherm’s model changed. The Freundlich model was the most representative isotherm model to describe metallic ions sorption. The 1H NMR spectra showed differences between LRM and NLRM and the acid-basic potentiometric titration elucidated that acid-leaching procedure affected the root material sorption sites once only two predominant sorption sites were found for LRM (phenolic and amine, both able cations sorption) and five sorption sites (two carboxylic, amine and two phenolic) were founded for NLRM.