Environmental Engineering Reference
In-Depth Information
The effect of biofouling on various polymers and composites such as: PU, SR, polyester
(PET), GFRP, CFRP and SF placed for a period of one year in marine waters at a
depth of one meter was studied by Sudhakar and co-workers. These materials are
used widely in marine applications. SR with the lowest surface energy was the least
fouled [11]. The maximum barnacle attachment was seen on a hard surface (GFRP)
and the minimum was seen on a lexible surface (SR). Attachment of barnacles and
polychaetes are positively correlated with surface energy. Fouling load is positively
correlated with surface energy and hardness. The average temperature, pH, salinity
and dissolved oxygen of the sea water at the location during the study period were 28
± 2.04 ºC, 8.18 ± 0.08, 30.67 ± 4.16 (ppt) and 4.57 ± 0.31 (mg/l), respectively [11].
Surface hardness also affects the fouling of the surface. Hard surfaces lead to a higher
bioilm ( Table 4.4 ), than soft surfaces (correlation coeficient = 0.68, p<0.05). Surface
energy and surface hardness seem to positively affect the attachment of barnacles
(correlation coeficient of 0.87 and 0.79, respectively, Table 4.4 ). Similar results were
observed by Becker [20], on PC, polytetraluorethylene (PTFE), and copolymers made
from PTFE, and perluoro compounds and by Crisp and co-workers [21] on slate.
The literature mentions that hard hydrophilic surfaces enhance the attachment of
barnacles [6]. Surface energy positively affects the attachment of polycheates.
Table 4.4 Correlation coeficients between surface properties of the substrates
and bioilm at the end of 2 months of immersion of the polymers and
composites mentioned in Table 2.1, in the Bay of Bengal, South India
(p values <0.05 are reported here)
Bioilm parameters measured
Surface roughness
Surface hardness
Surface energy
Fouling load
0.68
0.93
Total viable count
0.58
Chlorophyll a
0.45
TSS
-0.73
0.57
0.48
Adenosine triphosphate
0.56
0.82
Barnacles
0.87
0.79
Polychaetes
0.72
Table 4.4 shows the correlation coeficients of the surface properties of the polymers/
composites with hardness, surface roughness and surface energy on biofouling. A
 
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