As an associated element, aluminum (Al(III)) has a negative effect on the purity of rare earth gadolinium (Gd(III)). Three pyridinium-based ionic liquids ([(CH₂)_nCOOHpyr][NTf₂], n = 3, 5, 7) were proposed as the solvent in liquid-liquid extraction for separation of the Al(III) impurity from Gd(III) in this study. The effect of pH value of the aqueous phase, diluent type, extraction time and temperature on the extraction separation of Al³⁺ from GdCl₃ solution were investigated systemically. The results show that the separation factor β of Al(III)/Gd(III) is up to 340 by adjusting the pH value of the aqueous phase which is higher than the values of other reported systems, and the removal efficiency of Al(III) could reach 97.1%, with the recovery efficiency of Gd(III) of 85.6% through one-time extraction using a mixture of ionic liquids [(CH₂)₇COOHpyr][NTf₂]-[C₄mim][NTf₂] as the extractant. The slope analysis and infrared spectroscopic characterization indicated that the extraction mechanism of Al(III) by the [(CH₂)₇COOHpyr][NTf₂]-[C₄mim][NTf₂] system follows the cation exchange mechanism. After the extraction, 0.08 mol/L hydrochloric acid aqueous solution was used to strip Al(III) from the ionic liquid phase, and complete recovery of Al(III) could be realized. The extraction efficiency of the [(CH₂)₇COOHpyr][NTf₂]-[C₄mim][NTf₂] system for separation of Al(III) is still more than 97.8% after recycling for 8 cycles.

作为伴生元素，铝 (Al(III)) 对稀土钆 (Gd(III)) 的纯度有负面影响。提出了三种基于吡啶鎓的离子液体 ([(CH ₂ ) _n COOHpyr][NTf ₂ ], n  = 3, 5, 7) 作为液液萃取的溶剂，用于从 Gd 中分离 Al(III) 杂质（ III）在这项研究中。系统研究了水相pH值、稀释剂种类、萃取时间和萃取温度对GdCl ₃溶液萃取分离Al ^{3+的影响。}结果表明，分离因子β通过调节水相的 pH 值，Al(III)/Gd(III) 的去除率高达 340，高于其他已报道的体系，Al(III) 的去除率可达 97.1%。通过使用离子液体[(CH ₂ ) ₇ COOHpyr][NTf ₂ ]-[C ₄ mim][NTf ₂ ] 的混合物作为萃取剂的一次萃取，Gd(III)的回收率为85.6% 。斜率分析和红外光谱表征表明[(CH ₂ ) ₇ COOHpyr][NTf ₂ ]-[C ₄ mim][NTf _{2对Al(III)的萃取机理}]体系遵循阳离子交换机制。萃取后，用0.08 mol/L的盐酸水溶液从离子液相中反萃取出Al(III)，实现了Al(III)的完全回收。[(CH ₂ ) ₇ COOHpyr][NTf ₂ ]-[C ₄ mim][NTf ₂ ]体系对Al(III)分离的萃取效率在循环8次后仍能达到97.8%以上。