Biomedical Engineering Reference
In-Depth Information
1.4.3.2 Water Remediation
Iron NPs that contain a small amount of palladium have been shown to transform harmful products
in groundwater into less harmful end products (He and Zhao 2005). For example, the NPs are able
to eliminate organic chlorine, a carcinogen, from water and soil contaminated with chlorine-based
organic solvents that are normally used by dry cleaners. The NPs facilitate the chemical reactions
that change the solvents to benign hydrocarbons.
1.4.3.3 Sensors
Owing to the dynamic surface of NMs, they make exceptional sensors that are susceptible to small
changes in the concentration of the species (Luo et al. 2006). Applications such as the detection
of anthrax and the quantification of chromium in wastewater have been demonstrated using NPs
(Alagarasi 2011, Wang et al. 2004b).
1.4.3.4 Fuel Cells
Electrochemical fuel cells translate chemical energy into electricity. The electrodes are mainly
responsible for the channeling of energy, making their surface area important. Another factor
that plays a key role in the performance of the fuel cell is the electrocatalyst. In an ideal structure,
an electrode must have a large surface area for a maximized contact with the catalyst, reactant
gas, and electrolyte, thereby facilitating gas transport, supply, and good electronic conductance
(Alagarasi 2011).
Microbial fuel cells (MFCs) have been used in the generation of electricity by utilizing bacte-
ria. In MCFs, bacteria oxidize the substrate (sugar, starch, or alcohols) to generate electricity and
clean water by ridding the waste water of those compounds (Figure 1.8) (Liu et al. 2004). This
allows for a significant reduction in sanitation costs and the purification of domestic and industrial
e
-
e
-
Glucose
e
-
e
-
H
+
MED
red
NAD
+
H
2
O
MED
+
NADH
CO
2
O
2
NAD
+
H
+
H
+
Bacterium
Anode
Cathode
FIGURE 1.8
Schematic representation of microbial fuel cell. The bacterium in the cell either directly or
indirectly transfers electron to the electrode resulting in the production of electricity in this setup. (Reprinted
with permission from Rabaey, K., and W. Verstraete. 2005.
Trends in Biotechnology
23(6):291-298.)
