Extraction of Iron (II) and Nickel (II) ions from Aqueous Solution using Palm Kernel Oil as a Green Extractant

A phase mediated, solvent extraction process was used in the removal of Fe (II) and Ni (II) ions from aqueous solutions. The organic phase was constituted with palm kernel oil (PKO) and the aqueous phase was equally modified with ethylenediaaminetetraacetic acid (EDTA), as a chelating agent. Gas Chromatography Mass Spectrometry (GC-MS) and Flame Atomic Absorption Spectrophotometry (FAAS) were used to analyse the chemical composition of the PKO and the concentration of the metal ions present in the aqueous solutions, after the extraction procedures, respectively. The results from the GC-MS showed that the PKO consisted of fatty acids, mainly tridecanoic acid (32.16 %), pentadecanoic (18.02 %), dodecanoic (16.13 %), and hexadecenoic acid (12.4%). The concentrations of the metal ions after our extraction procedures were used to evaluate the percent extraction efficiency and the distribution ratio. High values of percent extraction efficiency, in the range of 97.37 – 99.21 percent and 97.19 – 99.78 percent, were achieved for the removal of Fe (II) and Ni (II) ions respectively. Equally, the values of the distribution coefficient were in the range of 37.03 – 124.93 as well as 34.57 – 459.79 for the removal of Fe (II) and Ni (II) ions. The percent extraction efficiency and the distribution coefficient increased with increase in initial concentration of these metal ions in the aqueous solution as well as with the volume of PKO that served as the organic phase. This was due to an equilibrium position shift in the direction that favoured the removal of the Fe (II) and Ni (II) ions from the aqueous phase. The presence of EDTA caused a further increase in the case of the extraction of Fe (II) ions but minimal effect was noted in the case of Ni (II) ions. The results obtained revealed that PKO, with or without a chelating agent, can serve as an excellent green extractant for the removal of Fe (II) and Ni (II) metal ions from aqueous solutions.