A novel ion exchange-electrodialysis hybrid system to treat rare-earth oxalic precipitation mother liquid: Contamination reduction, efficient Y3+ recovery, and acid separation

• Published in: Desalination Vol. 565; p. 116815
• Main Authors: Zhou, Hengcheng, Zheng, Zhi, Chen, Yongjing, Wan, Yinhua, Sun, Jiaxuan, Zhang, Tianci, Chen, Dongdong, Shi, Shaoyuan, Ju, Peihai
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.11.2023
• Subjects: Acid separation; Ion exchangers; Membrane fouling; Rare earth recovery; Selective electrodialysis; CC; DOM; REEs; Acid separation; REOP; Selective electrodialysis; SED; Ion exchangers; Rare earth recovery; R-T; W-R-T; Membrane fouling; DC
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2023.116815

A novel ion exchange process combined with selective electrodialysis (SED) process has been demonstrated to not only efficiently recover low concentration rare-earth elements (REEs) and separate hydrochloric acid, but also significantly reduce membrane fouling. Two resins with different functional groups were selected for pretreatment and recovery of Y3+ from Y rare-earth oxalic precipitation (Y REOP) mother liquor. CH-93 resin showed a Y recovery rate of over 94 %, and the Y recovery efficiency remained above 90 % after 5 cycles. The mother liquor treated with resin (R-T) and the untreated mother liquor (W-R-T) were subjected to acid separation via SED, and membrane fouling was systematically evaluated. Compared with W-R-T group, the hydrochloric acid recovery efficiency of R-T group increased by 21.01 % (12 V), and the unit energy consumption decreased by 54.30 % (12 V). The results of 3D fluorescence excitation-emission matrix (3D-EEM) and fluorescent region integration (FRI) showed the dissolved organic matter (DOM) on AEM and CEM in R-T group both decreased by >45 %. The AEM of W-R-T group showed the highest fluorescence intensity ratio in V region (36 %), indicating humic acid-like substances were the main cause of AEM fouling. Generally, this study provides a new approach for the resource utilization of REOP mother liquor. [Display omitted] •Ion exchange combined with SED was confirmed to be efficiently Y element recover and hydrochloric acid separation.•CH-93 resin can significantly reduce unit energy consumption and the membrane fouling of electrodialysis.•32 % of the dissolved organic matter in the Y REOP mother liquor was accounted for humic acid-like substances.•The removal of DOM by resin was quantified via fluorescence regional integration (FRI) method.