ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

Ahmed M. Shahr El-Din, Hoda E. Rizk, Emad H. Borai, and El Sayed M. El Afifi

Analytical Chemistry and Control Department, Hot Laboratories and Waste Management Center, Egyptian Atomic Energy Authority, Cairo, Egypt

E-mail: ahmhoda@gmail.com

Received: 10 October 2022  Accepted: 21 December 2022

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.

Keywords: Lanthanides; Extraction chromatography; Separation; High-grade monazite

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02643-w

Chemical Papers 77 (5) 2525–2538 (2023)