哈萨克斯坦褐煤腐植酸与金属离子的相互作用

Interaction of Metal Ions with Humic Acids of Brown Coals of Kazakhstan

本文研究了从埃基巴斯图兹盆地褐煤中分离出的腐植酸与Fe^(3+)、Cu^(2+)、Ni^(2+)和Co^(2+)的相互作用过程。结果表明,腐植酸对重金属离子的吸附取决于阳离子的浓度和性质,其吸附量大小依次为Fe^(3+)>Cu^(2+)>Ni^(2+)>Co^(2+)。随着腐植酸浓度的增加,离子和金属的收率提高。新吸收峰的出现以及羧酸根、羰基和羟基对应伸缩和变形振动吸收峰的位移证明了金属-腐植酸体系中离子交换和络合反应的发生。这些反应中的分光光度结果和由于腐植酸去质子化导致的溶液pH值降低也可以印证这些反应过程的发生。因此,基于腐植酸对金属阳离子吸附程度的数据、红外光谱法和分光光度法的分析结果,可以证明,Fe^(3+)、Cu^(2+)、Ni^(2+)、Co^(2+)与腐植酸之间的相互作用是通过给电子官能团的离子机制和络合机制实现的。用循环伏安法对Cu^(2+)-腐植酸体系进行的电化学研究也表明,腐植酸与铜阳离子间发生了相互作用。铜离子对腐植酸的修饰表明,固定在分散的腐植酸表面的铜具有电化学活性,这对于在修饰的玻碳-腐植酸电极上实现电催化反应非常重要。

This paper investigates interaction processes of the Fe^(3+),Cu^(2+),Ni^(2+),and Co^(2+) cations with humic acids isolated from brown coals of Ekibastuz basin.It was demonstrated that the sorption of heavy metal ions by humic acids(HA)depends on the concentration and nature of cations and decreases in the order of Fe^(3+)>Cu^(2+)>Ni^(2+)>Co^(2+);while increase in the concentration of humic acids(HA)results in the higher yield of ions and metals.The occurrence of ion exchange and complexation reactions in metalhumic acid systems is confirmed by the appearance of new bands and the shift of the absorption bands corresponding to stretching and deformation vibrations of carboxylate ions,C=O and OH groups.The occurrenceof these processes is also evidenced byspectrophotometric data,as well as adecrease in the pH of the solution due to deprotonation of humic acids during these reactions.Thus,based on the data on the degree of sorption of metal cations by humic acids,the results of infra-red spectroscopyand spectrophotometry ,it can be concluded that the Fe^(3+),Ni^(2+),Co^(2+),Cu^(2+) cations interact with HA by the ionic mechanism and by the complexation mechanism with electrondonating functional groups.Electrochemical studies of the Cu^(2+)-humic acid system carried out by the method of cyclic voltammetry also indicate the occurrence of the interaction of humic acid with copper cations.Modification of humic acid with copper ions shows the electrochemical activity of copper immobilized on the surface of dispersed humic acid,which is important for the implementation of electrocatalytic reactions on modified glassy carbonhumic electrodes.