Many technological solutions contain valuable components as waste and can become an additional source of rare-earth elements to meet the needs of modern production. The development of technologies based on commercially available and cheap sorbents reveals the possibility for rare earth recovery from various solutions. This paper provides research on using a combination of KU-2-8 and AV-17-8 ion exchangers in different molar ratios for cerium ions sorption from its nitrate solution. The mutual activation of the ion exchangers in an aqueous medium provides their transformation into a highly ionized state by the conformational and electrochemical changes in properties during their remote interaction. The ion exchange dynamics of solutions were studied by the methods of electrical conductivity, pH measurements, and atomic emission analysis of the solutions. The research showed that the maximum activation of polymers was revealed within the molar ratio of KU-2-8:AV-17-8 equal to 3:3. In more detail, in comparison to AV-17-8, this interpolymer system showed an increase in the sorption degree by more than 1.5 times after 6 h of interaction. Moreover, compared with KU-2-8, the same interpolymer system showed an increase in the degree of cerium ions sorption by seven times after 24 h of interaction. As a result, the total cerium ions sorption degree after 48 h of sorption by individual KU-2-8 and AV-17-8 was 38% and 44%, respectively, whereas the cerium ions sorption degree by the same interpolymer system in the molar ratio 3:3 became 51%. An increase in the sorption degree of cerium ions by the interpolymer system in comparison with individual ion exchangers can be explained by the achievement of a high ionization degree of ion exchangers being activated in the interpolymer system by the remote interaction effect.
Features of the extraction of yttrium and lanthanum with an intergel system based on hydrogels of polyacrylic acid and poly-4-vinylpyridine To predict the sorption activity and selectivity of hydrogels, the effect of mutual activation of polymer networks in the intergel system was studied. The intergel system of the hydrogel of polyacrylic acid ((hPAA)) and the hydrogel of poly-4-vinylpyridine (hP4VP), which was studied at a distance through the volume of the solvent in the absence of direct contact between the polymer networks, were chosen as the object of study. Intergel systems have been investigated using methods for measuring electrical conductivity, pH, and gravimetry. The mutual activation of La 3+ and Y 3+ ions with the intergel system in an aqueous medium was also studied. It has been established that as a result of the remote interaction of the studied hydrogels, their mutual activation occurs, leading to a significant change in their electrochemical and conformational properties. At certain ratios of acidic and basic hydrogels, a significant increase in the sorption of lanthanum and yttrium ions is observed in comparison with the initial hydrogels. These results indicate the appearance of ionized structures with optimal conformation, providing an optimal ligand environment around lanthanum and yttrium ions.
The paper deals with the sorption of lanthanum ions by an interpolymer system consisting of sulfonic cation exchanger KU2-8 and anion exchanger AV-17-8. To predict the sorption activity of the intergel system, the mutual activation of the KU2-8 sulfonic cationite with the AV-17-8 anionite in the aqueous medium was initially studied. Due to the mutual activation of hydrogels in the course of their remote interaction, the polymer macromolecules pass into a highly ionized state, which leads to a significant increase in the degree of extraction of lanthanum ions from polymer hydrogels in intergel vapors as compared to the initial polymers. We calculated the degree of extraction of lanthanum ions by the interpolymer system KU2-8: AV-17-8, the degree of binding of the polymer chain (in relation to lanthanum ions) with the initial ion exchangers and the interpolymer system KU2-8: AV-17-8. Based on the data obtained, a comparative analysis of the sorption of lanthanum ions by individual sorbents and an interpolymer system was carried out within the limits of the ratio KU2-8: AV-17-8 = 5: 1–1: 5. It has been established that the maximum degree of sorption of lanthanum ions by the KU2-8: AV-17-8 interpolymer system is observed within the ratio KU2-8: AV-17-8 = 2: 4 at 48 hours of remote interaction of the interpolymer system and is 54.73 mol. %, at which the degree of binding of the polymer chain is 6.15%
The remote interaction between a weak polyacrylic acid polyelectrolyte (gpac) and a weak polyethyleneimine polybase (gpei) is studied as a function of time at their different molar ratios and states in an aqueous medium. To predict the possibility of activation of the studied hydrogels, electrochemical properties were studied by conductometry and pH metry. During pH measurement, it was found that 24 hours of pH have the lowest values, indicating a high content of H+ ions in the aqueous medium. The dependence of the specific electrical conductivity, the maximum value at the ratio of 3:3 (PAC:PEI) and it coincides with the result of pH from the ratio of components. The obtained results indicate that significant changes in the electrochemical and conformational values of the initial macromolecules in the interpolymer system occur in this interpolymer system. Thus, studies have shown on the presence of a remote interaction between hydrogels and their mutual activation. With an increase in the content of one of the hydrogels in the solution, a significant increase in the swelling of hydrogels is observed in proportion to the concentration of the second component, which indicates their mutual activation.
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