Research Interest
Novel Upconversion Phosphor Materials for Visible-Light Activated Disinfection
Our group is pioneering in developing sustainable technologies for water and surface disinfection with the ultimate goal of applying them to the developing world where proper infrastructure lacks. We are the first to report in the literature on the development and verification of lanthanide-doped silicate-based upconversion phosphors that convert visible light to germicidal UV light to effect disinfection. We are also developing a highly innovative approach of employing organic upconversion phosphors that shift the frequency of incident light through sensitized triplet-triplet annihilation. Polymers containing a pair of organic sensitizers and emitters serve as host materials that enable sub-bandgap sensitization of semiconductor photocatalysts. These composite materials exhibit high-efficiency upconversion to generate UV from visible light or blue light from green light.
Environmental Implication and Application of Carbonaceous Nanomaterials
The environmental impact of fullerenes, both C60 and carbon nanotube (CNT), is of great concern due to projections for wide spread application and bulk production in near future. Recent discoveries that C60 forms nano-scale water-stable aggregates upon release to water and that CNT forms stable aggregates with natural organic matter have redefined our view on their environmental impact as potential water contaminants. Our group studies dispersion characteristics of fullerenes in natural water, their interaction with natural water constituents, and their chemical (e.g. ozone and radicals) and photochemical reactivity. Our more current research involves application of fullerene's phototochemical reactivity for application in water treatment.
High-Pressure Membrane Processes for Emerging Contaminant Treatment
Our group studies transport mechanism of several emerging water contaminants through nanofiltration and reverse osmosis membranes with the ultimate goal of better designing the membrane processes for effective water reclamation and reuse. Contaminants of interest include hormone such as 17beta-estradiol, selected human and veterinary antibiotics, such as sulfamethoxazole, trimethoprim, erythromycin, ciprofloxacin, and carbadox, various nitrosamines disinfection by-products and their precursors, boron in seawater and engineered nanomaterials.
Ozone Disinfection Process Design and Optimization
Optimizing ozone disinfection processes to provide adequate inactivation of Cryptosporidium parvum oocysts (i.e., the pathogen with the greatest resistance to chemical disinfectants) with minimum production of disinfection by-products such as bromate has been very challenging to many water treatment utilities. We use a computer simulation, full-scale field testing, and laboratory experiments to develop a better design tool for ozone disinfection processes. Recently, we have been developing 3-dimensional laser induced fluorescence technique to visualize and quantify the mixing conditions in ozone reactors and UV disinfection reactors.
Solving Real World Engineering Problems
Our group has been involved in various real world projects as demanded by local governments, utilities, and engineering companies. For example, we studied the problem of unexpectedly low monochloramine stability in the water treatment facility of the City of Tampa, FL and successfully provided a solution that immediately impacted current treatment practices. In another project, a novel emulsion liquid membrane process to treat organic and metallic contaminants from industrial wastewater was developed. We also have investigated water quality in the Gwinnett County distribution system networks through model simulation as well as field sampling and laboratory experiments. More recently, we focus on novel disinfection and water treatment technologies based on membrane processes and novel catalyst materials for application in developing world.
Research Projects
1.
Quantitative Insights on Environmental Implication of Functionalizing
Fullerenes, National Science Foundation, $310,000, 2012-2015
2.
Optimizing Upconversion Phosphor Materials for Antimicrobial Surface
Coating, Hwaseung T&C, $879,630, 2011-2014
3.
Converting Visible Light to UVC: Lanthanide Upconversion Nano-Phosphors for
Light-Activated Biocidal Surface Development, National Science Foundation,
$318,939, 2011-2013
4. Laboratory and Field Scale Evaluation of the Homespring Central Water Purifier Phase II, GE Foundation, Co-PI: Kevin Caravati and Joseph Hughes, 2010, $200,000
5.
Developing Novel Surface Immobilized Photocatalysts Using Functionalized
C60,
National Science Foundation, $159,713, 2010-2012
6.
Coagulation-Ceramic
Membrane Filtration Processes for U.S. Surface Water Treatment: the Effect
of Coagulation and Membrane Fouling, Water Research Foundation, 2010-2012,
$20,000 from Water Research Foundation and $60,000 from Cash Contribution
and $10,000 in-kind contribution from GS Engineering &
Construction Corporation
7.
Developing Surface Disinfection Techniques For Human Norovirus Indicators,
Co-PI: Min Cho, Centers for Disease Control and Prevention (CDC), 2010,
$9,990
8.
Boron Rejection
Simulation In Full-Scale Seawater Reverse Osmosis Systems, GS Construction &
Engineering, Subcontracted under Korea Institute of Construction Technology
(KICT), 2009-2010, $76,500
9. Laboratory and Field Scale Evaluation of the Homespring Central Water Purifier, GE Foundation, Co-PI: Kevin Caravati and Joseph Hughes, 2009, $80,000
10.
Evaluation of Computational Fluid Dynamics Modeling Approaches Applied to
Ozone Contactor Design, USEPA, PI: Thorsten Stoesser, Co-PI: Jaehong Kim,
2009-2010, $14,043
11.
Developing a Novel Membrane Pore Size Analysis Technique Using Quantum Dots,
Korea Institute of Industry Technology, 2008-2009, $40,000
12.
Development of Automation Control System for Sequential Disinfection
Processes, Korean Ministry of Environment, Subcontract Under Korea Institute
of Construction Technology (KICT), 2008-2011, $250,000
13.
Removal of Emerging Contaminants by Reverse Osmosis Membranes, Korean
Ministry of Construction and Transportation, Subcontracted Under Korea
University,
2007-2012, $351,064
14. Visualization and Quantification of UV Dose and Mixing in UV Reactors by 3D Laser-Induced Fluorescence, American Water Works Association Research Foundation (Unsolicited Program), Co-PI: Philip Roberts, Thorsten Stoesser, Harold Wright, and Kyunghyuk Lee, 2007-2009, $257,251
15.
Design, Construction, and Feasibility Testing of a
Computer-Automated Remote-Controlled Pilot-Scale Drinking Water
Treatment System & Practical Application of a
Distribution System Model,
Gwinnett County, GA, Subcontractor: Dr. James Amburgey, University of South
Carolina at Charlotte, 2007-2008, $120,780
16.
Investigating Mixing in Baffled Ozone Contactors Using 3-D Laser Induced
Fluorescence and Reactive Transport Model, USEPA, Co-PI: Philip Roberts,
2006-2007, $14,677
17.
Optimization of Ozone Contactor Design and Operation Parameters through
Laser Induced Fluorescence, Hankuk Engineering, Co., LTD., Co-PI: Philip
Roberts, 2006-2007, $35,000
18. Fate and Transformation of C60 Nanoparticles in Water Treatment Processes, USEPA Science to Achieve Results (STAR) Grant, Co-PI: Joseph Hughes, 2005-2008, $426,013
19.
A
Computer-Based Design of New Ozone Contactor Treating Paldang Dam Reservoir
Water, Shinwoo Engineering, 2005, $10,759
20.
Heavy Metal And Ionic Species
Removal From Phosphoric Acid Solutions:
Phase I – Emulsion Liquid Membrane, Tata Chemicals, Ltd., 2005-2006,
$45,278
21. Boron Rejection by Reverse Osmosis Membranes: National Reconnaissance and Mechanism Study – Phase I., Bureau of Reclamation, US Department of Interior, 2004-2006, $125,885
22.
Removal of Emerging Trace Organic Contaminants in Surface Water by
Ultrafiltration and Nanofiltration, Saehan Industries, Inc., Co-PI:
Ching-Hua Huang, 2004-2005, $45,000
23.
Water Quality and Treatment Process Study I. Understanding the fate of
organic matter at the DLT Water Treatment Plant of Tampa City, City of
Tampa, FL. Subcontract under Gannett Fleming, as Co-PI, PI: Michael Perdue,
2004-2006, $89,081
24. Water Quality and Treatment Process Study II. Evaluation and Assessment of Biological GAC filters at the DLT Water Treatment Plant of Tampa City, City of Tampa, FL. Subcontract under Black & Veatch, 2004-2006, $99,436
25.
Lanier Filter Plant Treatment Process and Distribution System Study,
Gwinnett County Public Utilities, Gwinnett County, GA, Co-PI: James
Amburgey, 2004-2005, $68,004
26.
M/DBP Model for the Optimization of Full-Scale Process Design and Operation:
Enhancing the Ozone Contactor Simulation Software, USEPA, subcontract under
University of Illinois at Urbana-Champaign, 2004, $16,325