Adavodi Roshanak, Zuffranieri Adriana, Romano Pietro, Rahmati Soroush, Vegliò Francesco
Department of Industrial and Information Engineering and Economics (DIIIE), Engineering Headquarters of Roio, University of L'Aquila, 67100 L'Aquila, Italy.
Materials (Basel). 2025 Aug 15;18(16):3826. doi: 10.3390/ma18163826.
The growing demand for ultra-low sulfur fuels has intensified interest in recovering strategic metals from the large volumes of hazardous hydrodesulfurization catalysts that are discarded yearly. This work evaluates a task-specific ionic liquid, tri-n-octylammonium bis(2-,4-,4-trimethylpentyl)-phosphinate [TOA][Cy272], synthesized by the acid-base neutralization of tri-n-octylamine and Cyanex 272. FT-IR spectroscopy confirmed complete proton transfer and the formation of a stable ion pair. Liquid-liquid extraction tests were conducted with synthetic Co-Ni-Mo solutions (0.1-2.5 g/L each), a varying ionic liquid concentration (10-50 vol%), pH (1.5-12.5), and organic/aqueous ratio (1:1). At 35 vol% of ionic liquid and pH 2, the extraction efficiency for Mo reached 94%, with separation factors βMo/Ni = 12 and βMo/Co = 7.5; Co and Ni uptake remained ≤15%. Selectivity decreased at higher metal loadings because of ionic liquid saturation, and an excessive ionic liquid amount (>35%) offered no benefit, owing to viscosity-limited mass transfer. Stripping studies showed that 1 M NHOH stripped about 95% Mo, while leaving Co and Ni in the organic phase; conversely, 2 M HCl removed 92-98% of Co and Ni, but <5% Mo. Overall Mo recovery of about 95% was obtained by a two-step extraction/stripping scheme. The results demonstrate that [TOA][Cy272] combines the cation exchange capability of quaternary ammonium ILs with the strong chelating affinity of organophosphinic acids, delivering rapid, selective, and regenerable separation of Mo from mixed-metal leachates and wastewater streams.
对超低硫燃料日益增长的需求，使得从每年大量废弃的危险加氢脱硫催化剂中回收战略金属的关注度不断提高。本研究评估了一种特定任务离子液体，即通过三正辛胺与Cyanex 272酸碱中和合成的三正辛基铵双（2,4,4-三甲基戊基）次膦酸酯[TOA][Cy272]。傅里叶变换红外光谱证实了质子的完全转移和稳定离子对的形成。采用合成的Co-Ni-Mo溶液（各0.1 - 2.5 g/L）、不同的离子液体浓度（10 - 50 vol%）、pH值（1.5 - 12.5）以及有机相/水相比例（1:1）进行液 - 液萃取试验。在离子液体浓度为35 vol%且pH值为2时，Mo的萃取效率达到94%，分离因子βMo/Ni = 12，βMo/Co = 7.5；Co和Ni的萃取率保持在≤15%。由于离子液体饱和，在较高金属负载量下选择性降低，并且过量的离子液体用量（>35%）由于传质受粘度限制而无益处。反萃研究表明，1 M的NHOH可反萃约95%的Mo，而Co和Ni留在有机相中；相反，2 M的HCl可去除92 - 98%的Co和Ni，但Mo的去除率<5%。通过两步萃取/反萃方案，Mo的总回收率约为95%。结果表明，[TOA][Cy272]结合了季铵离子液体的阳离子交换能力和有机次膦酸的强螯合亲和力，能够从混合金属浸出液和废水流中快速、选择性且可再生地分离Mo。
