Extraction of Cu(II) from aqueous solution using di-2-ethylhexylphosphoric acid (D2EHPA) diluted in cooking palm oil: Optimization using response surface methodology (RSM)

This study aimed to develop an optimal condition of Cu(II) extraction from aqueous solution using cooking palm oil as a potential organic solvent. Response surface methodology (RSM) based on central composite rotatable design (CCRD) was used to optimize the two important process variables namely pH equilibrium (pH
_eq
) and D2EHPA concentration for the Cu(II) extraction. The adequacy of the model was examined, and it was found to be statistically significant. The optimum condition for the Cu(II) extraction was as follows: 4.48 pH
_eq
and 76.00 mM D2EHPA concentration. The optimum predicted percentage Cu(II) extraction was 99.58% and the actual value was 98.08%. The above results shows that the RSM study based on CCRD is adaptable for Cu(II) extraction studied and thus cooking palm oil are potential as greener substitutes for the conventional petroleum-based organic solvents.