TY - JOUR
T1 - Characterization of colored products formed during irradiation of aqueous solutions containing H2O2 and phenolic compounds
AU - Chang, Jonathan L.
AU - Thompson, Jonathan E.
N1 - Funding Information:
We would like to acknowledge the generous support Jonathan Chang received from the Welch Foundation as a summer scholar. Materials, instruments and supplies were provided by Texas Tech University and the State of Texas. The authors also wish to extend their gratitude to Vera Mainz, Haijun Yao, and Furong Sun of the University of Illinois, and David Purkiss of Texas Tech University for their rapid and organized approach to ESI–MS and NMR analysis of the samples.
PY - 2010/2
Y1 - 2010/2
N2 - Irradiation of aqueous (pH = 5) mixtures containing hydrogen peroxide (1 mM) and phenolic compounds (10 mM) were found to produce visible light absorbing solutions over the course of several hours. The kinetics and products of these reactions were studied by UV-VIS absorbance, electrospray mass spectrometry, FTIR, fluorescence, and NMR and compared to humic-like substances commonly found in atmospheric particulate matter. It was determined the reactions leading to formation of color are quite general to this compound class, and the reactions proceeded more rapidly with hydroxyl or methoxy substitution ortho to the phenolic OH. However, para substitution generally slowed formation of colored compounds compared to the unsubstituted form. Mass spectrometry confirms compounds of several hundred Da formed in the reaction mixtures. The IR spectra of the reaction products bear similarity to that observed for authentic aerosol humic-like substances. The results indicate radical coupling of phenols and methoxylated phenols in tropospheric waters may contribute to humic-like particulate matter.
AB - Irradiation of aqueous (pH = 5) mixtures containing hydrogen peroxide (1 mM) and phenolic compounds (10 mM) were found to produce visible light absorbing solutions over the course of several hours. The kinetics and products of these reactions were studied by UV-VIS absorbance, electrospray mass spectrometry, FTIR, fluorescence, and NMR and compared to humic-like substances commonly found in atmospheric particulate matter. It was determined the reactions leading to formation of color are quite general to this compound class, and the reactions proceeded more rapidly with hydroxyl or methoxy substitution ortho to the phenolic OH. However, para substitution generally slowed formation of colored compounds compared to the unsubstituted form. Mass spectrometry confirms compounds of several hundred Da formed in the reaction mixtures. The IR spectra of the reaction products bear similarity to that observed for authentic aerosol humic-like substances. The results indicate radical coupling of phenols and methoxylated phenols in tropospheric waters may contribute to humic-like particulate matter.
KW - Airborne particulate matter
KW - Brown carbon
KW - Humic-like substances (HULIS)
KW - Light absorbing carbon
KW - OH radical
UR - http://www.scopus.com/inward/record.url?scp=73749086983&partnerID=8YFLogxK
U2 - 10.1016/j.atmosenv.2009.10.042
DO - 10.1016/j.atmosenv.2009.10.042
M3 - Article
AN - SCOPUS:73749086983
VL - 44
SP - 541
EP - 551
JO - Atmospheric Environment
JF - Atmospheric Environment
SN - 1352-2310
IS - 4
ER -