Araújo G C L, Lemos S G, Ferreira A G, Freitas H, Nogueira A R A
Grupo de Análise Instrumental Aplicada, Embrapa Pecuária Sudeste, Caixa Postal 339, 13560-970 São Carlos, SP, Brazil.
Chemosphere. 2007 Jun;68(3):537-45. doi: 10.1016/j.chemosphere.2006.12.054. Epub 2007 Feb 5.
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 0.14M HNO(3). 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 0.5M CH(3)COONH(4) medium at pH 6.5. For LRM the sorption was also studied in 0.5M KNO(3) medium. The acid pre-treatment increased the sorption capacity (SC) for all ions studied. For the KNO(3) medium, Cu(II) and Fe(III) sorption was higher than in CH(3)COONH(4) 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 (1)H 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.
在本研究中，使用巴伊亚雀稗根材料来阐明酸浸预处理和吸附介质对金属吸附的影响。将磨碎的巴伊亚雀稗根用0.14M HNO₃浸提。浸提后的根材料（LRM）和未浸提的根材料（NLRM）用于在pH 6.5的0.5M CH₃COONH₄介质中对Ni(II)、Cu(II)、Al(III)和Fe(III)进行流动吸附。对于LRM，还在0.5M KNO₃介质中研究了吸附情况。酸预处理提高了所研究的所有离子的吸附容量（SC）。对于KNO₃介质，Cu(II)和Fe(III)的吸附高于在CH₃COONH₄中的吸附，并且Ni(II)等温线模型的类型发生了变化。Freundlich模型是描述金属离子吸附的最具代表性的等温线模型。¹H NMR光谱显示LRM和NLRM之间存在差异，酸碱电位滴定表明酸浸提过程影响了根材料的吸附位点，因为LRM仅发现两个主要吸附位点（酚类和胺类，均能吸附阳离子），而NLRM发现了五个吸附位点（两个羧基、胺类和两个酚类）。
