Trace metals in water from crude oil: Surfactant and humic acid-enhanced partitioning.

摘要

All crude oil contains trace metals with nickel (Ni) and vanadium (V) generally being the predominant elements. These trace metals were formerly only considered a concern from the perspective of the fuel cracking process. The metals are generally complexed as porphyrins. The first step in our process was to determine how we could detect the free metal ions and porphyrin bound metals at expected low concentrations and in a speciated form. In addition, we were interested in whether surfactants enhanced the partitioning of trace metals to the water phase as the solubility would increase and thus pose other concerns as surfactants are used in remediation techniques. Finally we did a test with humic acids as a potential mechanism for the environment itself to release these metals to the groundwater.; Our research developed new methods for using ion chromatography (IC) with vanadium. This thesis discusses the perfecting of this detection and other methods utilized, with a special emphasis on Raman spectroscopy. The goal of our analysis was to answer questions on whether or not partitioning effects of trace metals could produce a potential toxic hazard in crude oil spills. We show that surfactants, such as Brij-35, when added to the water in contact with crude oil, tend to enhance the release of complexed metals into the water phase. In the natural environment, humic acids appear to have the capability to perform in a similar manner to surfactants; to cause the release of tightly bound porphyrin metals from crude oil.; Boscan crude oil was run in batch reactors using de-ionized water as the aqueous phase to look for partitioning effects. These studies show insignificant partitioning in experiments with time frames of one month to over two years. Brij-35 surfactant added did show an increased partitioning effect, but in a phorphyrin form and not as ionic metals. Subsequent humic acid experiments indicated that the environment has its own natural “solubilization” effect in releasing metals to groundwater. This seems particularly significant in areas of chronic spills, or even acute spills if the metal concentration is high and the oil comes into contact with water with high concentrations of humic substances.