Investigating Lanthanide Extraction with Varying 1-Alcohol Concentrations

Lns were extracted via solvent extraction, where equal volumes of organic and aqueous phases were used. Organic phases included 0.04 M TODGA (accounted for 97 wt%) with 1-alcohol PMs in n-dodecane, descriptions are listed in Table 1. As evident in Table 1 there are several gaps when comparing the concentration of 1-alcohol selected. 1-Octanol has been the most studied PM in literature, so a wide range of concentrations were selected (5, 10, 15, and 30 vol%) to further investigate the relationship between various 1-octanol concentrations. The concentrations of 10 and 15 vol% 1-alcohol were not selected for 1-hexanol, 1-decanol, and 1-dodecanol because the aim of this work was to determine the trend between varying 1-alcohol alkyl chain length at low and high concentrations. The low concentration of 5 vol% 1-alcohol was selected because 5 vol% is commonly used in literature to understand the fundamental chemistry in DGA systems. A high concentration of 30 vol% 1-alcohol was chosen as it is relevant to industrial applications. However, at 30 vol% 1-dodecanol a white precipitate formed at the interface during pre-equilibration. As 1-dodecanol has a melting point of 26 °C and the experiments were performed at room temperature (21 °C), this caused 1-dodecanol to form a precipitate. Since a precipitate formed, this prevented data collection for the 30 vol% 1-dodecanol system, and comparison between various 1-alcohol alkyl chain lengths with 1-dodecanol systems. The selected organic phases were pre-equilibrated with 1 M HNO₃ for 5 min at 2000 rpm and centrifuged for 5 min at 2800 rpm. A 0.85 mL aliquot of the pre-equilibrated organic phase was contacted with 0.85 mL of 3 mM Ln(NO₃)₃ in 1 M HNO₃ for 5 min at 2000 rpm and centrifuged for 5 min at 2800 rpm. Each Ln was individually contacted in triplicate for error analysis to evaluate trends in co-extracted solutes (Ln³⁺, H⁺, and H₂O) and FT-IR data across the period. Following extraction, the organic phase was removed for analysis with Karl Fischer (KF), FT-IR, and potentiometric titration.