Selective separation and purification of cerium (III) from concentrate liquor associated with monazite processing by cationic exchange resin as adsorbent

Abstract

The present study is directed to find the optimal conditions required for efficient separation and purification of Ce3+ as an analog for lanthanides from Fe3+, Th4+, and Zr4+ (interfering ions) using Amberlite IR120H (AIR120H) resin as a strongly cationic exchange adsorbent. The main factors affecting the separation processes had been investigated and optimized. Ce3+ (Ln3+) as an admixture with Fe3+, Th4+, and Zr4+ was successfully separated by batch and column techniques. The sorption efficiency (S, %) from different acidic media was in this order: HCl > HNO3 > H2SO4. In a quaternary mixture with Fe3+ and Th4+, the maximum separation factor between Ce3+ and Zr4+ was ~ 13 after 90 min of equilibration, and the sorption capacity of AIR120H resin for Ce3+ was 8.2 mg/g. The rate of adsorption was found to follow a pseudo-second-order kinetic model. Separation of the absorbed ions was achieved by desorption processes. Firstly, 98 ± 2% of loaded Ce3+ is fully desorbed by 1 M sodium acetate solution without interfering ions. Moreover, ~ 95% of Zr4+ is desorbed by 1 M citric acid solution. Finally, 85% of loaded Fe3+ and Th4+ ions are desorbed with 8 M HCl solution. The batch technique was applied to separate and purify Ln3+-concentrate in chloride liquor (LnCl3), coming from the caustic digestion of Egyptian high-grade monazite. However, the enhanced radioactivity in LnCl3 due to radium -isotopes (228Ra2+, 226Ra2+, 224Ra2+, 223Ra2+) and radio-lead (210Pb2+) is initially reduced by a factor of 92% (i.e., safe limit) by pH-adjustment. As result, it can be recommended that the sorption process by AIR120H resin is efficient and promising for exploring pure lanthanides from its minerals.

Reactivity of Rare-Earth Oxides in Anhydrous Imidazolium Acetate Ionic Liquids

“…Super-acidic ILs combined with a stream of chlorine gas also dissolve rare-earth oxides [11]; however, using a highly toxic gas does not achieve the aim of green chemistry. Nevertheless, there are also some existing reports on the direct dissolution of rare-earth oxides in ILs [12][13][14][15][16][17]. Water-stable ILs containing Brønsted acidic groups, in particular the very effective IL [Hbet][NTf 2 ] ([Hbet] + = betainium, [NTf 2 ] − = bis(trifluoromethylsulfonyl)imide), are much more suitable.…”