Metal organic frameworks as sorption media for volatile and semi-volatile organic compounds at ambient conditions

In this research, we investigated the sorptive behavior of a mixture of 14 volatile and semi-volatile organic compounds (four aromatic hydrocarbons (benzene, toluene, p-xylene, and styrene), six C-2-C-5 volatile fatty acids (VFAs), two phenols, and two indoles) against three metal-organic frameworks (MOFs), i.e., MOF-5, Eu-MOF, and MOF-199 at 5 to 10 mPa VOC partial pressures (25 degrees C). The selected MOFs exhibited the strongest affinity for semi-volatile (polar) VOC molecules (skatole), whereas the weakest affinity toward was volatile (non-polar) VOC molecules (i.e., benzene). Our experimental results were also supported through simulation analysis in which polar molecules were bound most strongly to MOF-199, reflecting the presence of strong interactions of Cu2+ with polar VOCs. In addition, the performance of selected MOFs was compared to three well-known commercial sorbents (Tenax TA, Carbopack X, and Carboxen 1000) under the same conditions. The estimated equilibrium adsorption capacity (mg.g(-1)) for the all target VOCs was in the order of; MOF-199 (71.7) > Carboxen-1000 (68.4) > Eu-MOF (27.9) > Carbopack X (24.3) > MOF-5 (12.7) > Tenax TA (10.6). Hopefully, outcome of this study are expected to open a new corridor to expand the practical application of MOFs for the treatment diverse VOC mixtures

Short and Long-Term Temporal Changes in Air Quality in a Seoul Urban Area: The Weekday/Sunday Effect

We present evidence on the short-term differences in airborne pollution levels in terms of weekday/weekend (WD/WN) and weekday/Sunday (WD/Sun) intervals. To this end, we analyzed the hourly data of important pollutants (nitric oxide (NO), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO)) using the data acquired in the Yong-San district of Seoul, Korea from 2009 to 2013. For each week, the pollutant ratio (Rw) was estimated through either WD/WN or WD/Sun. Here, a week is defined as Sunday through Saturday, WD as Monday through Friday and WN as Sunday and Saturday. The WD/Sun Rw geometric means (and range) were 2.02 (0.27–15.5) for NO, 1.29 (0.49–5.7) for NO2 and 0.89 (0.17–7.2) for O3 while the fraction of Rw (WD/Sun) > 1 were 81, 71 and 38%, respectively. NO and CO levels were much higher in October through March (during Autumn and Winter) than April through September (during Spring and Summer), reflecting the potential effect of fuel consumption (e.g., in terms of use patterns of nationwide city natural gas). Thus, we provide a broader interpretation on the occurrence patterns of the major pollutants (e.g., NO, NO2, O3 and CO) in relation to temporal changes in man-made activities