Copper Sorption by Coal Substances from Aqueous Solutions

Abstract

<p>The copper cations sorption by brown coal, humic acids and residual coal samples after the extraction of humic acid was studied by using the methods of spectroscopy FT-IR, EPR, Solid State CP/MAS <sup>13</sup>C-NMR. Samples of lignite (brown coal) of the Tisulsky deposit (TL) of Kansk-Achinsk brown coal basin (Russia), its naturaloxidized form (NOLF), as well as samples of the humic acids (HA) extracted from them, and the residual coal after the extraction of humic acids (RC) were used as sorbents. The copper cations sorption process by the investigated samples depends on contribution of several mechanisms in varying degrees. It may be an ion exchange; complexation with the functional groups of the electron donor; complexation to form the bond Me<sup>z+</sup> – HA due to the presence of the free π-electrons on the surface. The quantity of adsorbed copper cations depends on the functional and structural composition of the investigated samples. The copper cations sorption by the coals, humic acids and residual coals reduces the number of paramagnetic centers in the samples and the intensity of the NMR spectra. The copper cations sorption by HA from TL is determined by the significant contribution of the ion exchange process. HA from NOLF; initial TL and NOLF; RC TL and RC NOLF sorb copper cations mainly due to the formation of complexes with individual functional groups and the negatively charged surface portions. The data of <sup>13</sup>C-NMR and EPR studies have shown that the aromatic structures make the main contribution to the complexation.</p>