A new method for the concurrent treatment of Cr­(VI)-contaminated wastewater and production of the useful I2 chemical was developed. The method is based on the redox reaction between Cr­(VI) and I– that occurs when an aqueous wastewater solution containing Cr­(VI) and I– is frozen, producing I2 and allowing for the effective removal of Cr. The redox reaction occurs primarily because of the accumulation of Cr­(VI), I–, and protons in the ice grain boundaries formed during freezing (i.e., the freeze concentration effect). This effect was verified by confocal Raman spectroscopy and the experiments varying I– concentration and pH. The reduction of Cr­(VI) (20 μM) was near complete after freezing at I– concentrations ≥ 100 μM, pH ≤ 3.0, and temperatures ≤ −10 °C. The freezing method (liquid cooling vs air cooling) had little effect on the final Cr­(VI) reduction efficiency but had a significant effect on the Cr­(VI) reduction rate. The freezing method was also tested with Cr­(VI)-contaminated electroplating wastewater samples, and simultaneous Cr­(VI) reduction and I2 production proceeded rapidly in a frozen solution but was not observed in an aqueous solution. Additionally, other substances in electroplating wastewater did not reduce the rate and final efficiency of Cr­(VI) reduction and I2 production. Therefore, the freezing/Cr­(VI)/I– system can be considered a feasible approach to water-energy nexus technology for simultaneous I2 production and Cr­(VI)-contaminated wastewater treatment.

<p>In this presentation, we will discuss the top down emission estimates of SO<sub>2</sub> and volatile organic compounds using mass spectrometers integrated on a research aircraft with a fast-meteorological sensor. The study area is four coal power plants, one steel mill, and one petrochemical industrial facility, located in the Tae-ahn Peninsular in South Korea 50 km away from the southern tip of the Seoul Metropolitan Area. We conducted 20 research flights to closely monitor emissions from each facility.  We will present detailed analysis of instantaneous emission rates to verify emission inventories to proceed their impacts to regional air quality, particularly towards the Seoul Metropolitan Area with a population of 25 millions, using a semi-Lagrangian photochemical box model.</p><p> </p>

No abstract

Abstract. Ketene, a rarely measured reactive VOC, was quantified in the emission plumes from Daesan petrochemical facility in South Korea using airborne PTR-TOF-MS measurements. Ketene mixing ratios as high as ~ 40–50 ppb were observed in the emission plumes. Emission rates of ketene from the facility were estimated using a horizontal advective flux approach and ranged from 84–316 kg h−1. These emission rates were compared to the emission rates of major VOCs such as benzene, toluene, and acetaldehyde. Significant correlations (r2 > 0.7) of ketene with methanol, acetaldehyde, benzene, and toluene were observed for the peak emissions, indicating commonality of emission sources. The calculated average ketene OH reactivity for the emission plumes over Daesan ranged from 3.33–7.75 s−1, indicating the importance of the quantification of ketene to address missing OH reactivity in the polluted environment. The calculated average O3 production potential for ketene ranged from 2.98–6.91 ppb h−1. Our study suggests that ketene has the potential to significantly influence local photochemistry and therefore, further studies focusing on the photooxidation and atmospheric fate of ketene through chamber studies is required to improve our current understanding of VOC OH reactivity and hence, tropospheric O3 production.

Abstract. A compound was observed using airborne proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) measurements in the emission plumes from the Daesan petrochemical facility in South Korea. The compound was detected at m/z 43.018 on the PTR-TOF-MS and was tentatively identified as ketene, a rarely measured reactive volatile organic compound (VOC). Estimated ketene mixing ratios as high as ∼ 50 ppb (parts per billion) were observed in the emission plumes. Emission rates of ketene from the facility were estimated using a horizontal advective flux approach and ranged from 84–316 kg h−1. These emission rates were compared to the emission rates of major known VOCs such as benzene, toluene, and acetaldehyde. Significant correlations (r2 > 0.7) of ketene with methanol, acetaldehyde, benzene, and toluene were observed for the peak emissions, indicating commonality of emission sources. The calculated average ketene OH reactivity for the emission plumes over Daesan ranged from 3.33–7.75 s−1, indicating the importance of the quantification of ketene to address missing OH reactivity in the polluted environment. The calculated average O3 production potential for ketene ranged from 2.98–6.91 ppb h−1. Our study suggests that ketene, or any possible VOC species detected at m/z 43.018, has the potential to significantly influence local photochemistry, and therefore, further studies focusing on the photooxidation and atmospheric fate of ketene through chamber studies are required to improve our current understanding of VOC OH reactivity and, hence, tropospheric O3 production.