Qualitative Assessment of PC88A and HBTA Extractants in Lithium Recovery Processes Using Solvent Extraction

Abstract

This study compares the solvent-extraction behavior of lithium (Li) using the cost-effective extractant PC88A (2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester) and the more expensive extractant HBTA (4,4,4-Trifluoro-1-phenyl-1,3-butanedione). PC88A achieved an optimal extraction rate of 37.6% at pH 5.43, with a maximum rate of 41.4% at pH 7.80. It required six stages at a 5/1 O/A ratio (organic phase-to-aqueous phase ratio) for 98% extraction and three stages at a 15/1 ratio for 100% extraction. In contrast, HBTA showed an optimal extraction rate of 86.2% at pH 6.23 and a maximum rate of 92.9% at pH 11.95. HBTA achieved 100% extraction with three stages at a 1/1 O/A ratio and 98% with one stage at a 5/1 ratio. By applying McCabe–Thiele methods, this study figured out that to achieve a 98% lithium extraction rate at 5/1 of O/A ratio, PC88A requires 6 stages, whereas HBTA achieves the same extraction rate in just 1 stage. This result indicate that a sixfold difference in efficiency if these extractants used in the counter-current solvent-extraction process. These findings reveal HBTA’s striking superiority over PC88A in terms of efficiency. Future studies should include evaluations of equipment and extractant costs, and overall efficiency.