Related Experiment Video
Updated: Jan 25, 2026

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet VUV Synchrotron Radiation
Published on: October 30, 2012
Degradation of iodinated disinfection byproducts by VUV/UV process based on a mini-fluidic VUV/UV photoreaction
1College of Environment, Zhejiang University of Technology, 18 Chao-wang Road, Hangzhou, 310014, China; Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 18 Shuang-qing Road, Beijing, 100085, China.
Abstract:
This study investigated the VUV/UV photodegradation of three iodinated disinfection byproducts (I-DBPs), namely, triiodomethane (TIM), diiodoacetamide (DIAcAm) and triiodoacetic acid (TIAA), based on a mini-fluidic VUV/UV photoreaction system (MVPS). The pseudo-first-order rate constants (k) of TIM, DIAcAm and TIAA under VUV/UV irradiation (1769, 1301 and 1174 m2 einstein-1, respectively) were higher than those under UV irradiation (1003, 832 and 766 m2 einstein-1, respectively). The enhancement of photodegradation could be attributed to the indirect HO• oxidation rather than the direct VUV photolysis. As a whole, compared with the indirect HO• oxidation, the direct UV photolysis had a relatively greater contribution to the degradation of the three I-DBPs, especially DIAcAm and TIAA (ca. 57% and 60%, respectively). The two electron-withdrawing groups in DIAcAm and TIAA (i.e., acylamino and carboxyl) decreased the electron density of the C-I bonds, thus weakening the electrophilic attack of HO•. The iodine in the three I-DBPs was released to form I- and a small fraction (< 6%) of I- was oxidized to IO3-, indicating that HO• preferred to break the C-I bonds rather than oxidize I-. The direct UV photolysis proceeded via H2O-catalyzed deiodination reactions, while the indirect HO• oxidation proceeded via deiodination reactions along with HO• addition. The VUV/UV photodegradation of the three I-DBPs was more favored at an acidic pH but inhibited by the water matrix components (i.e., NOM, Cl- and alkalinity) to different extents.
Related Concept Videos
UV–Vis Spectrum
The UV–Vis spectrum of a molecule is the plot of its absorbance versus wavelength. The plot is drawn by taking molar...
UV–Vis Spectrometers
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency,...
UV–Vis Spectroscopy of Conjugated Systems
One of the factors influencing λmax is the extent of conjugation in...
UV–Vis Spectroscopy: Woodward–Fieser Rules

