Highly Efficient Interception and Precipitation of Uranium(VI) from Aqueous Solution by Iron-Electrocoagulation Combined with Cooperative Chelation by Organic Ligands

• Published in: Environmental science & technology 2017-12, Vol.51 (24), p.14368-14378
• Main Authors: Li, Peng, Zhun, Bao, Wang, Xuegang, Liao, PingPing, Wang, Guanghui, Wang, Lizhang, Guo, Yadan, Zhang, Weimin
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Chelates; Chelation; Chemical precipitation; Coagulation; Contaminants; Efficiency; Electrocoagulation; Elution; Flocculation; Impurities; Interception; Iron; Ligands; Low concentrations; Macromolecules; Oxides; pH effects; Precipitation; Purification; Strategy; Uranium; Wastewater; Wastewater treatment; Water Pollutants, Radioactive; Zeta potential
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/acs.est.7b05288

A new strategy combining iron-electrocoagulation and organic ligands (OGLs) cooperative chelation was proposed to screen and precipitate low concentrations (0–18.52 μmol/L) of uranium contaminant in aqueous solution. We hypothesized that OGLs with amino, hydroxyl, and carboxyl groups hydrophobically/hydrophilically would realize precuring of uranyl ion at pH < 3.0, and the following iron-electrocoagulation would achieve faster and more efficient uranium precipitation. Experimentally, the strategy demonstrated highly efficient uranium­(VI) precipitation efficiency, especially with hydrophilic macromolecular OGLs. The uranium removal efficiency at optimized experimental condition reached 99.65%. The decrease of zeta potential and the lattice enwrapping between U-OGLs chelates and flocculation precursor were ascribed to the enhanced uranium precipitation activity. Uranium was precipitated as oxides of U­(VI) or higher valences that were easily captured in aggregated micelles under low operation current potential. The actual uranium tailing wastewater was treated, and a satisfied uranium removal efficiency of 99.02% was discovered. After elution of the precipitated flocs, a concentrated uranium solution (up to 106.52 μmol/L) with very few other metallic impurities was obtained. Therefore, the proposed strategy could remove uranium and concentrate it concurrently. This work could provide new insights into the purification and recovery of uranium from aqueous solutions in a cost-effective and environmentally friendly process.