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Molecular Characterization of Dissolved Organic Matter and Its Subfractions in Refinery Process Water by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
journal contribution
posted on 2015-12-17, 08:16 authored by Yongyong Li, Chunming Xu, Keng H. Chung, Quan ShiDissolved organic matter (DOM) in
oil refinery process water was
fractionated by XAD-8 resin techniques into four subfractions: hydrophobic
acid (HOA), hydrophobic base (HOB), hydrophobic neutral (HON), and
hydrophilic substance (HIS) fractions. Negative and positive electrospray
ion (ESI) Fourier transform ion cyclotron resonance mass spectrometry
(FT-ICR MS) was used to characterize the composition of DOM and its
subfractions. Compounds with multi-oxygen atoms were found to be predominant
in DOM by either negative or positive ESI analysis, which are similar
in composition to most other treated water samples. The DOM in the
HOA fraction had a similar molecular composition to that of raw process
water by negative ESI analysis. The DOM in the HOB fraction had a
low molecular weight (MW) when analyzed by positive ESI, and basic
nitrogen compounds, such as N1 class species, were found
to be predominant. The DOM in the HON fraction was predominantly O2 class species. The DOM in the HIS fraction had a relatively
wide MW distribution. All of the compounds of DOM in the HIS fraction
exhibited low double bond equivalents (DBE) and low carbon numbers.
The results showed that the use of the XAD-8 resin fractionation technique
is valuable for characterizing trace quantities of DOM components
in process water because their spectral peaks would otherwise be obscured
by other abundant peaks. The origin and determination of chlorine-containing
compounds, which are abundant in the negative ESI mass spectra of
HOB, were discussed.