Separation of oil from oil water emulsion by the use of alginate gel encapsulated iron oxide and graphene oxide nanoparticles

Abstract

Crude oil is used extensively around the world as a source of energy and as a means of producing various petroleum products. However, apart from being an excellent energy source, crude oil can also be a major pollutant in the form of oil spills. Crude oil spills can occur on land and in the ocean during the drilling, production, transportation or storage stages. While it is possible to reduce the damage caused to the environment by an oil spill, it is almost impossible to completely remove the adverse effects. New techniques need to be developed to clean-up oil spills at higher rates and with increased efficiency. The use of nanoparticles (NPs) for oil spill clean-up has gained popularity in recent years. This research focuses on the use of alginate gel as an immobilizing agent for nanoparticles that are then used for the removal of heating oil from an oil-water mixture. Iron Oxide and Graphene Oxide Nanoparticles were immobilized using sodium alginate in calcium chloride. The concentration of the nanoparticles was varied from 1 g/L to 5 g/L. The immobilized nanoparticles were then added to an oil-water mixture which was prepared by spiking heating oil in methanol and adding the solution to deionized water to achieve uniform distribution. 10 mL samples containing residual oil were extracted from the heating oil and water mixture at regular intervals and were analyzed for the residual oil. Measurements were carried out for residual hydrocarbons using Gas Chromatography/Mass Spectroscopy (GC/MS), Fluorescence Spectroscopy and Ultraviolet--visible spectroscopy (UV-Vis). Results from GC/MS show the highest percentage of oil being removed from the mixture by 2 g/L iron oxide (77%) and 2 g/L graphene oxide (81%) NPs. Analysis for residual hydrocarbons based on the time of contact showed promising results, with 75% of oil removed in 70 minutes. Further, based on the data obtained it was observed that the nanoparticles reached saturation after 70 minutes and were unable to remove additional quantities of oil from the mixture. Changing the nanoparticles from Iron Oxide to Graphene Oxide increased the amount of oil removed by 4%. This research will assist future development of oil spill clean-up and water treatment techniques that make use of nanoparticles as sorbents.