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| Prof. Ching-Hua
Huang, Environmental Engineering |
Research Interests
My research interests are in the area of Environmental Chemistry.
I am particularly interested in the reactivity, transformation and fate of emerging
contaminants and nanomaterials in natural and engineered aquatic systems. As the variety and quantity of
synthetic chemicals and new materials in use continue to grow, our
environment is being affected by ever-increasing number of contaminant
agents. The organic emerging contaminants that have been our focus include
endocrine disruptors, pharmaceuticals,
personal care products, and nitrosamine disinfection by-products, and the range of
compounds in investigation is continuing to expand. The typically low concentrations, unconventional
physicochemical properties and largely unknown reactivities of emerging
contaminants present new research challenges and demands. Our
group is particularly interested in the advanced chemical oxidation,
interfacial phenomena, and analytical development for emerging
contaminants and novel nanomaterials. One of our strong interest is to elucidate the
fundamental kinetics and mechanisms of
transformation reactions involving emerging contaminants and new
nanomaterials under environmental conditions. The ultimate goal is to build
the knowledge basis that allows us to predict the environmental fate of
numerous other potential contaminants..
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Transformation of
Emerging Contaminants with Metal
Oxides and Soils
Recent studies indicate that antibiotics and antibacterial agents are being released into the environment
from sewage effluent, land applications of animal waste and agricultural runoffs. The
presence of antibacterials in the environment may foster proliferation of
resistant pathogens and pose threats to human health. A better understanding of
the fate of these contaminants is imperative. Due to their high polarity and low
biodegradability, the interactions of antibacterials with soil minerals likely play a
critical role in their transformation and transport.
This project investigates the transformation of antibacterials with manganese, iron and
aluminum oxides, and oxide-rich soils with the aim of understanding these processes
mechanistically. Several important structural groups of antibacterials (e.g., phenolic,
fluoroquinolones, aromatic N-oxides, tetracyclines, etc.) are being systematically investigated. The
research objectives are to (1) identify antibacterials that are susceptible to metal
oxide-facilitated oxidation, (2) identify the oxidation products of
antibacterials, (3)
assess the structure-activity relationships for the oxidation of
antibacterials with metal
oxides, and (4) elucidate reaction kinetics, pathways and mechanisms. The research
approach utilizes novel analytical techniques and integrates kinetic and mechanistic
investigation with computational chemical modeling.
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Catalytic Reactivity
of Novel
Nanostructured Materials for Pollutant Degradation
Active research in nanotechnology in recent years has produced a range of novel nanosized
and nanostructured materials. The unique properties of these new
nanomaterials offer great promises in potential applications in
environmental pollution remediation.
We have been working collaboratively with Prof. Ken Sandhage at the School of
Materials Science and Engineering at Georgia Tech to explore the catalytic
reactivity of a group of innovative
nanostructured materials for potential applications in pollution
remediation. The nanomaterials (in titania or other mineral composition)
are synthesized via unique shape-preserving chemical conversion
processes of diatom silicate bioclastic structures. The resulted
nanomaterials consist of crystallite nanoparticles in well-controlled
and reproducible three-dimensional (3-D) shapes. Preliminary studies
have indicated enhanced catalytic activity of these nanomaterials and
their photocatalytic reactivity is also being explored.
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| (Advanced) Chemical
Oxidation of Emerging Contaminants
Our group has thus far investigated whether chlorination and
chloramination commonly employed
in water/wastewater treatment are effective at removing antibacterial
agents and whether potential
harmful by-products are being produced as a result of these treatment
processes.
Laboratory experiments are being conducted to investigate reaction kinetics and mechanisms
and to examine the relationships between compound removal, chemical properties, process
parameters, and water matrices. Results of this study will help establish a knowledge
basis to predict removal of related antibiotics and other emerging micropollutants by
chemical oxidation in water and wastewater treatment facilities and improve risks
assessment for antibacterial contaminants.
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Potential
Nitrosamine Formation under Water and Wastewater Treatment Conditions
Recent
studies have found N-nitrosamines, particularly N-nitrosodimethylamine (NDMA), as drinking
water contaminants due to reactions during chlorination and chloramination of water and
wastewater. The finding of nitrosamines as
disinfection by-products strongly indicate that these contaminants may be widespread in
many water treatment and distribution systems. The
highly carcinogenic effects of nitrosamines pose significant health risks to the
population. Regulations of nitrosamines in
water supplies are currently hindered by inadequate information regarding their formation
and health effects. Thus it is imperative to
obtain a better understanding of the formation, exposure and potential health effects of
nitrosamines through drinking water engineered pathways in order to develop means to
reduce formation of these compounds and minimize public exposure in drinking water
supplies.
This research project focuses on systematic investigation to determine
whether certain commonly used water treatment polymers may contribute to
nitrosamine formation in water and wastewater
treatment plants, identify factors that will enhance or reduce such a formation, and
elucidate the involved mechanisms. The study results will provide
the basis for strategies in minimizing nitrosamine formation and environmental health risks
associated with water treatment polymers.
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| Removal of Emerging
Contaminants by Membrane Processes
This project is a collaborative effort with Prof. Jaehong
Kim at the School of Civil and Environmental Engineering at Georgia Tech
to investigate the removal and mechanisms of ultrafiltration, nanofiltration
and reverse osmosis processes for hormones, antibacterials agents and
nitrosamines.
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Occurrence of Pharmaceuticals in the Environment
This earlier project involved assessing the occurrence of antibiotics/antibacterial
agents and
estrogenic hormones in water sources that were intended for indirect or direct water
reuse. The research efforts included (1) development of novel and robust analytical
methods (e.g., SPE and LC/MS) to quantify antibiotics in complicated water matrices, (2)
occurrence survey of antibiotics in municipal wastewater effluent and surface waters, and
(3) investigation of the fate and transformation of antibiotics through various
conventional and advanced water/wastewater treatment processes.
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