Environmental Engineering Reference
In-Depth Information
(a)
(b)
(c)
Outer membrane
O
-
•
OH
O
-
•
OH
Peptidoglycan
Cytoplasmic membrane
Outer membrane
Peptidoglycan
Cytoplasmic membrane
FIGURE 25.11
Photokilling of bacteria through membrane damage. (From Sunada, K. et al.,
Environ. Sci. Technol
., 37, 4785, 2003.)
Intact cell
Reversible cell damage
Protein
RNA
K
+
K
+
Leakage of large molecules
Leakage of ions and
small molecules
irreversible cell damage
CO
2
H
2
O
Minerals
Degradation of cellular
components
Complete
mineralization
FIGURE 25.12
Mechanism of bacterial killing. (From Foster et al.,
Appl. Micro. Biol
., 90, 1847, 2011.)
25.12 Photocatalytic Degradation of
E. coli
Using
Nitrogen-Doped Titanium Dioxide
Photocatalysis is an effective technology for removing pathogens from water. It has many
advantages compared with the conventional disinfection methods. Chlorine is known to
react with organic matter present in water and produce organochlorine products. These
compounds are carcinogenic in nature. Other methods such as UV treatment and ozo-
nation are expensive, and these methods cannot be used as sustainable water treatment
methods in rural areas. Heterogeneous photocatalysis is highly eficient in removing
organic compounds and microorganisms from water.
