Research and Educational Activities of the MI
Lab
Our research and education centers
on physicochemical/biological processes emphasizing nanomaterials and
membrane technologies for water safety and sustainability. Ongoing/previous
research and educational topics are described as follows:
Current Projects
This research exploits the promising properties of
graphene oxide (GO) nanomaterials to synthesize a radically new class of
layered water purification membranes and to surface-modify existing membranes
for exceptional performance. Experiments are designed to determine and
optimize critical parameters that control water flux and selectivity of GO
membranes, elucidate the photocatalytic and antifouling mechanisms of
GO-based composite materials, and investigate the performance of GO membranes
in removing representative water contaminants. The education plan includes
recruiting underrepresented students, outreaching to K-12 students and STEM
teachers, directing undergraduate teams for scheduled showcases in
multi-level exhibitions, developing new courses emphasizing state-of-the-art
technology, and revitalizing existing courses on engineering sustainability.
This research is
to develop, test, and study a novel membrane separation system that holds great
promise as the next-generation, highly sustainable water purification
technology for emergency and/or household drinking water supply.
The experiments
are designed to test the hypothesis that the resistance of membranes modified
by PEMs towards biofouling is controlled by its anti-adhesive and
antimicrobial properties. PEM parameters (e.g., constituent polyelectrolytes
and NPs and number of bilayers within PEMs) will be systematically varied in
order to investigate their influence on the anti-adhesive and antimicrobial
properties of the membranes. To probe the membrane’s anti-adhesive
properties, the kinetics of bacterial deposition on the membrane during
filtration, as well as the adhesive forces between a bacterium and the
membrane surface, will be measured. The antimicrobial properties of the
membranes will be studied through the enumeration of bacterial colonies on
the membrane surface and by using a fluorescent dye technique to detect
deposited cells with damaged membranes. The biofouling resistance of
membranes modified by PEMs will be evaluated by monitoring the permeate flux
decline in long-term filtration experiments with bacteria suspensions.
Another component of this research will be to investigate the effects of the
above-mentioned PEM parameters on the rate of unintended NP leaching.
Finally, this research will examine several physical and chemical methods for
the in situ regeneration of PEM-NP assemblies on membrane surfaces and
evaluate the performance of the regenerated membranes.
Completed Projects
This project
integrates molecular simulation and multiscale
experimental characterization to achieve a molecular-level understanding of
the fouling of reverse osmosis and nanofiltration (RO/NF) membranes. RO/NF
membranes are increasingly being used for water separation and desalination.
However, the performance of RO/NF membranes is severely hampered by the
long-standing problem of colloidal/organic fouling. Development of efficient
fouling-mitigation strategies and highly fouling-resistant membranes relies
on the fundamental understanding of membrane-foulant
interactions. However, current experimental studies attempting to understand
the effects of membrane properties on fouling often draw inconsistent
conclusions. In addition, current efforts to develop antifouling materials
are mostly based on experimental trial-and-error, which is tedious,
expensive, and time-consuming. Therefore, we urgently need a more efficient
approach to designing new antifouling materials. Towards this goal, we will:
(1) develop a novel hybrid molecular simulation approach that is specifically
fit for simulating the long-time binding events between foulants and membrane
surfaces; (2) conduct multiscale experimental
characterization, including nanoscale interaction
force measurement by atomic force microscopy, microscopic direct-observation
of foulant-deposition on membrane surfaces, and
macroscopic characterization of long-term membrane fouling behavior; and (3)
integrate experimental measurements and molecular simulations to achieve a
molecular-level understanding of membrane fouling, thus greatly facilitating
the design of novel antifouling membranes.
This
Nanotechnology Undergraduate Education (NUE) in Engineering program at the
George Washington University (GWU) develops a program that prepares
undergraduate engineering students for careers or graduate studies in the
design of systems and devices employing biological nanotechnology. This goal
will be accomplished by infusing bio-nanotechnology into GWU's undergraduate
engineering degree programs with new content, in the form of new courses and
new laboratory experiments. With strong institutional support, faculty from
the Mechanical and Aerospace Engineering, Electrical and Computer
Engineering, and Civil and Environmental Engineering departments are
collaborating to develop six new courses along with a set of ten laboratory
experiments to enhance existing courses. Mi is developing a new undergraduate
course on applications of nanotechnology in environmental engineering and
their impacts on environmental sustainability. In addition, She is enhancing
an existing undergraduate hydraulics lab course by adding new experiments on
micro and nanoscale behavior of fluids.
 
NWRI-AMTA Fellowship for Membrane Technology (09/01/2010 - 08/31/2012, $20,000, awarded to Yaolin Liu, Doctoral Student in CEE, with Dr. Mi as
advisor)
Under the project
entitled “Biofouling of Forward Osmosis Membranes: Mechanisms and Fouling
Control,” Yaolin is systematically investigating
the fundamental issues related to the biological fouling of membranes in the
forward osmosis process. She is also developing novel anti-fouling strategies
through nanocomposite synthesis and surface modification.
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