High extraction efficiency of N,N,N′,N′-tetracyclohexyldiglycolamide for Sr(II): An experimental and crystal structure study

doi:10.1016/j.cjche.2024.09.015

Abstract

Abstract: To improve the ability of diglycolamide extractants for the extraction of Sr(II) from high-level waste liquid, N,N,N',N'-tetracyclohexyldiglycolamide (TCHDGA) was proposed and studied to extract Sr(II) from nitrate media. TCHDGA was prepared and characterized by ¹H nuclear magnetic resonance spectroscopy (NMR), ¹³C NMR, and fourier transform infrared spectroscopy (FT-IR). Various factors affecting extraction were studied systematically. In just 20 s, the extraction rate can reach approximately 98.2%. The extraction capacity of cyclohexyl-substituted extractant TCHDGA is tens of times higher than that with linear or branched chain alkyl. The chemical structure of the complex has been demonstrated to be [Sr 3TCHDGA]·(NO₃)₂, based on FT-IR, X-ray photoelectron spectroscopy (XPS), and crystal structure analysis. The crystal belongs to the monoclinic system, space group P21, and a strontium ion coordinates with nine oxygen atoms, all of which contribute from TCHDGA. The stripping rate can reach over 99% when using distilled water or 0.50 mol·L^-1 oxalic acid as stripping agents.

Key words: Strontium, TCHDGA extractant, Extraction, Crystal structure

摘要： To improve the ability of diglycolamide extractants for the extraction of Sr(II) from high-level waste liquid, N,N,N',N'-tetracyclohexyldiglycolamide (TCHDGA) was proposed and studied to extract Sr(II) from nitrate media. TCHDGA was prepared and characterized by ¹H nuclear magnetic resonance spectroscopy (NMR), ¹³C NMR, and fourier transform infrared spectroscopy (FT-IR). Various factors affecting extraction were studied systematically. In just 20 s, the extraction rate can reach approximately 98.2%. The extraction capacity of cyclohexyl-substituted extractant TCHDGA is tens of times higher than that with linear or branched chain alkyl. The chemical structure of the complex has been demonstrated to be [Sr 3TCHDGA]·(NO₃)₂, based on FT-IR, X-ray photoelectron spectroscopy (XPS), and crystal structure analysis. The crystal belongs to the monoclinic system, space group P21, and a strontium ion coordinates with nine oxygen atoms, all of which contribute from TCHDGA. The stripping rate can reach over 99% when using distilled water or 0.50 mol·L^-1 oxalic acid as stripping agents.

关键词: Strontium, TCHDGA extractant, Extraction, Crystal structure

Xiujing Peng, Ling Li, Haiyin Yu, Riming Hu, Jianhui Su, Miaomiao Zhang, Yu Cui, Xuchuan Jiang, Guoxin Sun. High extraction efficiency of N,N,N′,N′-tetracyclohexyldiglycolamide for Sr(II): An experimental and crystal structure study[J]. Chinese Journal of Chemical Engineering, 2025, 77(1): 1-9.

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