Maruthamuthu, S. et al. - Teesside's Research Repository

Impedance
Impedance spectroscopy data are presented in table VI and figure 5. In the control
system, Rt value was 32.93 kΩ/cm 2 , whereas in bacterial system, the Rt value was in the
range of 16.37 and 19.02 kΩ/cm 2 . It indicates that corrosion is higher in low resistance
systems. The nature of the curve in Bacillus sp. system also indicates that the corrosion is
due to activation control. Electrochemical impedance spectroscopy was used by Hashem
(2002) to study the effect of ammonia residuals on the corrosion of copper in seawater
polluted with ammonia and suggested that ammonia enhances the attack by dissolving the
complex with copper ion.
FTIR
FTIR spectrum for cupronickel with and without bacteria is presented in figure 6.
In the control system, a peak at 2355cm-1 was due to metal hydride bond (M-H). Peaks at
1630 cm -1 and 1117 cm -1 were due to the presence of metal –O-C and C-O (alcoholic)
stretching vibrations. The other peaks at 3288 cm -1 and 627 cm -1 were due to the presence
of hydrogen bond (O-H) and C-X bond stretches. In the presence of AG1, a peak at 3517
cm -1 was due to the N-H stretching vibration. A peak at 2767 cm -1 was correspond to the
OH- for COOH stretch. The peaks at 2354 and 1757 cm -1 were due to the presence of
metal-hydride bond (M-H) and metal- C-O respectively. The peaks at 1604, 1491 and
1265 cm -1 were due to the presence of Metal- O-C / N-H bending, N-H bending and
primary N-H (amine) stretch vibrations respectively. Peaks at 964 and 818 cm -1
corresponded to the -CH- out of bending and adjacent hydrogen atom vibration
respectively. In the presence of AG3, a peak at 3200 cm -1 was due to the N-H stretching
vibration. A peak at 2357 cm -1 corresponded to the metal - H (M-H). The peaks at 1757,
1627 and 1257 cm -1 were due to the presence of Metal- O-C / N-H bending, N-H bending
and primary N-H (amine) stretch vibrations respectively. Peaks at 1127 and 615 cm -1
were due to the C-O (alcoholic) and C-H out of plane/C-X stretch. FTIR study reveals
that the presence of nitrogen based compound was due to the attachment of bacteria or
physiological activity of ammonia producers on cupro-nickel 90:10.
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