Corn oil can remove heavy metals from water

RESEARCHERS have developed a process using vegetable oil to extract heavy metals such as lead or mercury from water.

A team from the Agricultural Research Service’s (ARS) National Center for Agricultural Utilization Research (NCAUR) in Illinois, US has been investigating safe ways to remove metal contaminants from liquids, solids, and gases and has created and patented a chemical method to modify vegetable oils into “functionalised” vegetable oils that separate heavy metal ions from water.

The team say using vegetable oil as a cleaning agent has its advantages as it is biodegradable, nontoxic and derived from renewable sources.

When the functionalised oil is mixed with water contaminated with toxic heavy metals, certain atoms in the oil bind to the heavy metals, pulling them out of the water. The clean water can then be separated from the heavy-metal-containing oil, and the oil can then be safely removed from the environment.

Rex Murray, research leader at NCAUR’s Bio-Oils Research Unit, said: “We analysed the amount of metal removed by different functionalised oils. Corn oil worked better than canola oil. We believe a different fatty-acid content in corn oil leads to its better metal-binding capabilities.”

The experiments were conducted at laboratory scale and the results show that the sulphide-modified corn oil absorbed 90% of the heavy-metals within 80 minutes.

The team believes the sulphur component in the thioether groups may be electron donors, thereby attracting the positive metal ions. This would explain why modified corn oil – which contains a greater number of thioether chains – works best.

The team says the research promises that modified vegetable oils would be a safe method to help clean up heavy-metal waste in the future.

The next step for the team will be to determine the effectiveness and ability of vegetable oils to extract other metals from solutions.