Abstract
Sulphur-modification of matter confers improved heavy metal affinity and
could be exploited in the treatment of heavy metal contaminated water.
This paper is aimed at comparing the selective liquid-liquid Ag+
sorption capacities of normal and thiolated: palm oil (PO), palm kernel
oil (PKO) and soybean oil (SBO), respectively. The vegetable oils were
modified with 1-heptanethiol and the thioether-functionalized (TF) oils
were utilized for the removal of Ag+ present as contaminant in water,
while the unmodified oils acted as controls. Liquid-liquid equilibrium
contact time was determined to be 6 hours. The result achieved after
equilibration, revealed the effectiveness of TF oils in the removal of
Ag+ from a 600 ppm AgNO3 (aq). While TF-SBO reduced the cation
concentration to a level less than the detection limit, TF-PKO only
showed appreciable sorption capacity (below 30 %) compared to the
sorption-inactive normal oils. The order of Ag+ sorption capacity
(TF-SBO > TF-PO > TF-PKO) was ascribed to the
various levels of unsaturation of fatty acid chains encountered in the
lipids, since higher number of sorption-active TF sites is achievable
with greater degree of fatty acid unsaturation. On that note, highly
unsaturated vegetable oils (such as that of Glycine max) were
recommended.