Hydrophobic Pollutant Removal from Water (Prof. Yuping Bao and Prof. C. Heath Turner)
Water pollution is a great concern to the public, and
the pollution are often a mixture of both organic and
inorganic
contaminants.
Hydrophobic
organic
contaminants are often introduced into the groundwater
and the environment as a result of industrial spills, such as
the recent oil spill in the Gulf of Mexico. This spill has
been a major disaster, significantly affecting the state of
Alabama. It is expected that many years (even decades)
will be required for the environment to recover, and the
low water solubility of these oil components delay the
recovery. It is a great challenge to remove the oil efficiently, without disturbing the ecosystem.
Here, we hypothesize that modified mesoporous silica nanoparticles can be used as a
reservoir to remove oil and other hydrophobic water contaminants. The strategy is to synthesize
silica nanoparticles with hydrophobic pores and water soluble surfaces, as shown. The rationale is
that water soluble silica nanoparticle can be well dispersed in water, and the inner hydrophobic pores
can allow hydrophobic molecules to be sequestered inside, for removal or further treatments. The
large surface areas of the inner pores provide high adsorption capacity for the hydrophobic oil
molecules. This structure design has been widely used for the delivery of hydrophobic drugs in drug
delivery applications. Furthermore, silica commonly exists in nature, particularly in the sea, and it is
environmentally-benign.
The REU student will synthesize the mesoporous silica nanoparticles using the famous Stober
method using tetraorthosilicate (TEOS), which results in
controlled pore sizes (4-15 nm) and particle diameters of up
Hydrophobic
to 500 nm.
The hydrophobic modification can be
pores
performed either during or post synthesis, using silanes of
type R-Si(OEt)3 with alkyl or aryl R groups. The REU
student will perform the surface modification by
introducing charged surface groups, such as phosphate.
Finally, a layer of TiO2 will be deposited on the silica
Hydrophilic
surfaces
nanoparticles surfaces, which absorbs UV light, providing a
means to break down the organic contaminants. The rate of 500 nm
diffusion, adsorption, and transport of the hydrophobic
molecules will be investigated using simulation methods. Silica nanoparticles: (a) Scanning electron
In particular, the REU student will use a well-developed microscope, and (b) schematic drawing of
simulation package (DL-POLY), which can be used to internal structures.
perform molecular dynamics simulations of transport in
the silica pores. These molecular dynamics simulations can be used to extract transport properties,
using time-correlation functions and other computational analysis techniques. Overall, this project
provides the student with a great opportunity to learn about the synthesis and characterization of
porous materials, as well as the function and utility of molecular simulation methods.