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Mechanism and kinetics of neutralization of copper-containing solutions with modified red slurries of alumina production

L.A. Pasechnik, I. S. Medyankina, S. A. Bibanayeva, S.P. Yatsenko

Institute of Solid State Chemistry of the Ural Branch of RAS, Yekaterinburg, Russia

DOI: 10.26456/pcascnn/2020.12.681

Abstract: Methods for modification red mud (RM) by treatment with hydrochloric acid and by carbonization to obtain sorption materials for extracting metals from acidic solutions are proposed. Modification of the RM by carbonation increases the area and volume of pores in the carbonized red mud (CRM), that leads to a higher sorption capacity up to 246 mg/g with simultaneously neutralization of the copper solution from 1,5 to 4,5 pH. The acid treatment leads to less positive effects on the extraction of copper. The sorption kinetics is described by both pseudo-first-order (R2 > 0,96) and pseudo-second-order (R2 > 0,98) equations, which determine the equivalent contributions to the overall speed of the process of the mass transfer and the ion interaction stages. A mechanism was studied and it was found that surface diffusion processes at the «solid-liquid» interface turn into the mass transfer of Cu2+ ions and chemical interaction with functional groups on the surface and inside the particles of modified muds. For the initial mud, these processes are almost equivalent. Desorption of copper with water and a solution of ethylenediaminetetraacetic acid (EDTA) has shown that the strength of bonds in the structure of CRM–Cu  and the stability of surface triple complexes Cu–EDTA–CRM are higher than for Cu–EDTA–RM. The potential have been demonstrated of creating sorption materials by used industrial waste, in particular alkaline red slurries, and their applications for the absorption of toxic metals from acidic wastewater for mutual neutralization and utilization of industrial waste from metallurgical industries – solid, gaseous and liquid.

Keywords: red mud, surface modification, acid treatment, carbonation, sorption, desorption, copper(II) ions.

Bibliography link:

Pasechnik, L.A. Mechanism and kinetics of neutralization of copper-containing solutions with modified red slurries of alumina production / L.A. Pasechnik, I. S. Medyankina, S. A. Bibanayeva, S.P. Yatsenko // Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials. – 2020. – I. 12. – P. 681-696. DOI: 10.26456/pcascnn/2020.12.681. (In Russian).

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