The corrosion of metals potentially reduces the shelf life of the infrastructure assets. Hence, it is necessary to reduce the corrosion to save considerable amount in structure. The organic corrosion inhibitors show the environmental toxicity which urged search for eco-friendly green corrosion inhibitors. Exopolysaccharide from Aureobasidium pullulans was studied with regard to its potential application as green inhibitor of corrosion. Isolation of A. pullulans was carried out from spinach. Biochemical and molecular characterizations of A. pullulans spi 10 were carried out. Pullulan production was maximum on fifth day of incubation. Pullulan precipitation was carried out by using isopropyl alcohol. The study of the corrosive stability of steel samples was conducted by the gravimetric method. The rate of corrosion, the degree of protection, and coefficient of protection were studied. With pullulan coating, the rate of corrosion was 0.348 × 10−3 g/cm2 .hour, which is approximately five times less than that of corrosion rate of steel plate without any protection (control). The degree of protection shown by biofilm (A. pullulans) is 24%, whereas the degree of protection governed by pullulan is 77%. The results reveal that biofilm of A. pullulans spi 10 and pullulan are both reliable and environment friendly green inhibitors that mitigate corrosion.
Key words: Corrosion, exopolysaccharide, pullulan, degree of protection.
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