Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and some long chain aliphatic sulfoxides

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl pyrazolone-5 (HPMBP) and aliphatic sulfoxides of varying basicities, viz di-isoamyl (DIASO), di-n-hexyl (DHSO), di-n-septyl (DSSO), di-n-octyl (DOSO), di-n-nonyl (DNSO), di-n-decyl (DDSO) or di-n-undecyl (DuDSO) sulfoxide has been studied at 30±0.1°C. Extraction with some of these sulfoxides has been studied at various fixed temperatures also. The organic phase equilibrium constant (log Ks) has been found to increase with the basicity of the sulfoxide up to DOSO beyond which there is a gradual decreasing trend which has been attributed to the effect of possible steric hindrance (spatial) involved in the bonding of the higher sulfoxides (greater than 8 carbon atoms) with UO₂ (PMBP)₂ chelate. This has been supported by thermodynamic data involved in these systems. The entropy values for sulfoxides with eight or more carbon atoms are much more negative as compared to the lower sulfoxides and are also in contrast to HTTA and BTFA systems with these sulfoxides studied earlier.