Fluorescence spectra of mineral oil-water intermixture

Abstract

Using highly pure water disposed by Milli-Qlabo purifying system of United States as background water, employing RF540 fluorescence spectrometer and selecting fourteen wavelengths as excitation wavelengths, this paper measured and analyzed excitation spectra and fluorescence spectra of oil-water intermixtures with different concentrations from eight domestic mineral crude oils, seven imported mineral crude oils and eight mineral product oils. Experiment results show that: all of these oils can emit fluorescence in broad range of excitation spectra, but the fluorescence quantum efficiency is different; optimal excitation wavelength is 254nm, while more effective excitation wavelength is 360nm, and the corresponding optimal fluorescence detection wavelengths are 360nm and 460nm; with the increment of concentration, relative intensities of fluorescence also increase linearly, which shows that they have obvious positive correlation and the correlation coefficient is above 0.9. Thus using fluorescence method to directly measure the content of mineral crude oil and product oil in water is feasible. Based on the experimental work, combining transfer characteristic of optical fiber, the ranges of optimal excitation wavelength and detection wavelength of mineral oil in water are confirmed, which founds for the on-line fluorescence measurement with optical fiber of micro-content of mineral oil in water.