Study of kinetic and structural characteristics of membranes in purification process of copper-containing solutions by electrodialysis

Abstract

This paper presents the analyzed results of the study of structural and kinetic characteris-tics of ion-exchange membranes MA-40, MK-40, PC Acid 60 and CM(H) (RALEX®) during sep-aration and concentration of copper-containing solutions in the electrodialysis process. In partic-ular, the sizes of amorphous and crystalline regions of the membrane material structure and the degree of crystallinity were determined, the retention factor of cation Cu2+ and anions NO3- and SO42- were calculated. It was found that for mA-40 and MK-40 membranes the structure of the membrane material changes during water saturation, what in turn can affect the kinetics of mass transfer through the membrane. In addition a low sensitivity of membrane material to mechanical and thermal loads under cyclic operating conditions is detected. This is confirmed by the coinci-dence of diffraction angles at which peaks of dry and water-saturated samples of membranes are observed, and by a non-significant change in the x-ray degree of crystallinity of the membrane material within 5-7% in the smaller side for water-saturated samples. The data, which were ob-tained during this work, indicate a relatively good cleaning of copper-containing solutions by elec-trodialysis from extraneous ions (NO3- and SO42-) at high values of Cu2+ cations concentration. In the initial section, slightly less than 90% of Cu2+ cations are retained, while NO3- and SO42- anions remain significantly less - about 16.7% and 25.7%, respectively. It should be noted that the most optimal parameters of electrodialysis are required for maximizing the efficiency of concentration.