Heavy metal sorption using thiolated oils of Elaeis guineensis and Glycine max

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 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 a contaminant in water, while the unmodified oils acted as controls. The 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 simulated water. While TF-SBO reduced the cation concentration to a level less than the detection limit, TF-PKO only showed appreciable sorption capacity (below 30%) relative to the normal oils. The order of Ag+ sorption capacity (TF-SBO > TF-PO > TF-PKO) was ascribed to various levels of unsaturation of fatty acid chains encountered in the lipids. A higher number of sorption-active TF sites is achievable with a greater degree of fatty acid unsaturation. On that note, highly unsaturated vegetable oils (such as that of Glycine max) were recommended.