Date/Time
Date(s) - 27/02/2020
1:30 pm - 2:30 pm

Environmentalfate and degradation of organic contaminants: From priority pollutants toemerging ones

Date:                             Thursday, February 27, 2020

Time:                              1:30p.m.  

Place:                             ABB 165

Abstract: 

In 1977, U.S. EPA included 126 compounds intheir Priority Pollutant List based on their toxicity, occurrence in theenvironment, and availability of analytical methods at the time. Polycyclicaromatic hydrocarbons (PAHs) and chlorinated hydrocarbons (CHCs) are the twomajor groups in the list. PAHs are generated from incomplete combustion ofcarbonaceous materials such as fossil fuels and biomass and are a well-knowngroup of carcinogens. Surface soil is the major sink for PAHs in theenvironment, and soil particles can enter human digestive tract viaunintentional ingestion. An in vitro digestive model with a third-phaseabsorptive sink was developed and used to assess the bioaccessibility of PAHsin soot/soil after ingestion, which highly improves the risk assessment on PAHexposure. CHCs, on the other hand, are widely used in the industry andprevalent in most contaminated groundwater. CHCs tend to appear in thenonaqueous phase liquids at the bottom of the aquifers, and thus require insitu source zone treatments. Sulfidated nanoscale zerovalent iron (S-nZVI)particles have been developed to degrade various CHCs and show great promisefor in situ remediation of contaminated groundwater. With the development of analyticalchemistry and the advances in instrumentation, a huge number of emergingcontaminants have been detected in the environment. Per- and polyfluoroalkylsubstances (PFASs) are the most concerning emerging contaminants in recentyears because of their toxicity, bioaccumulative potential, and persistency.PFASs are often encountered together with CHCs in groundwater. The potentialdegradation and interaction of nZVI with PFASs was characterized. Thedegradation mechanism and reaction pathways of representative PFASs duringsulfate radical based advanced oxidation processes were successfully addressedby using density functional theory (DFT) calculations in synergy withexperimental kinetics data.