Polymer inclusion membranes (PIMs) exhibit great potential in the separation and recovery of valuable materials from wastewater and secondary resources. In this work the effect of alkyl chain configuration of the functional carriers on the physicochemical properties and permeability of PIMs was investigated. Three tertiary amine isomers with different alkyl chain configurations were selected as carriers: trioctylamine, triisooctylamine, and tris(2-ethylhexyl)amine. Operating conditions like carrier contents, feed solution pH, phenol concentration, and stripping solution properties were also investigated. The results obtained in this study indicate that tertiary amines with less branched alkyl chains perform better phenol transport efficiency. Furthermore, the transport efficiency decreased rapidly with increasing steric hindrance of the carriers. Trioctylamine-based PIM displayed optimal extraction efficiency of 92.8 % and stripping efficiency of 90.8 % due to its lower steric hindrance, higher hydrophilicity, and larger crystallinity. Phenol extraction and stripping efficiencies remained above 85.7 % and 80.8 % after 8 cycles, demonstrating excellent stability.
Zirconium (Zr) and hafnium (Hf) are very important in nuclear and high-temperature applications, but their similar physical and chemical properties bring great challenges to separation. The current extraction methods have defects, such as low efficiency at high metal concentration. In this article, a zirconium (Zr)/hafnium (Hf) solvent extractive separation from sulfuric acid solutions using trioctylamine (TOA) as the extractant was researched at room temperature. The aqueous solution is prepared using zirconium sulfate (containing Hf), and the concentration of metal ions (Zr4+and Hf4+) was about 1.096 mol·L−1. The effects of the aqueous acidity, the concentration of TOA, the contacting time, and the organic to aqueous O/A ratio on the separation of Zr and Hf were investigated. It is observed that the Zr can be extracted in the organic phase selectively, and the optimal conditions were: TOA concentration of 40 vol%, organic to aqueous O/A ratio of 3, contacting time of 5 min. Under these conditions, the single-stage extraction rate of Zr is 61.23%, while the Hf is almost not extracted. The mechanism of Zr extraction by TOA was studied through the saturation capacity and slope methods. Based on the results, it is believed that the structure of the extracted complex may be [R3NH]2[Zr(SO4)3]. This study provides a new approach for the development of industrialized Zr-Hf separation.
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