Anomalous Sorption of Neodymium and Praseodymium Ions by Intergel System Polyacrylic Acid Hydrogel – Poly-4-Vinylpyridine Hydrogel

Abstract

This paper is devoted to study of sorption properties (sorption degree, polymer chain binding degree) of intergel system hydrogel of polyacrylic acid (hPAA) – hydrogel of poly-4-vinylpyridine (hP4VP) in relation to neodymium and praseodymium ions. It was found that remote interaction of the polymers in intergel pairs provides significant changes of the electrochemical and volume gravimetric properties. Strong increase of the swelling degree of hPAA is observed at the ratio 17%hPAA-83%hP4VP; significant increase of swelling degree of hP4VP is observed at the ratio 83%hPAA-17%hP4VP. Individual hydrogels of PAA and P4VP do not have sufficiently high sorption properties – sorption degree of neodymium and praseodymium ions is not higher than 65 %, polymer chain binding degree is not higher than 55 %. High ionization of hPAA and hP4VP due to remote interaction effect provides significant increase (up to 30 %) of the sorption properties. Maximum sorption of neodymium and praseodymium ions occurs at the ratios 83%hPAA-17%hP4VP and 50%hPAA-50%hP4VP (sorption degree is 93.5 % and 93.6 %, respectively). The highest values of polymer chain binding degree (in relation to neodymium and praseodymium ions) are observed at the ratios 83%hPAA-17%hP4VP and 50%hPAA-50%hP4VP – binding degree is 73.2 % and 75.4 %, respectively. Remote interaction provides possibilities for creation of innovative sorption technologies for selective sorption of aimed rare-earth elements.