Journal Articles
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Item Need of natural biocides in antifouling paints for prevention of marine pollution(International Journal of Innovation Research & Development, 2015-07) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S."Antifouling paints were developed to prevent marine growth on ship hulls in the middle of the 19th century. As they were designed to continuously leach biocides at the paint/seawater interface which were the predominant means of controlling fouling for a vast majority of the vessels, over a period of years in the latter part of the last century there has been a marked improvement in the effective life of antifouling paints. Different types of antifouling paints came into being but after a particular breakthrough when self- polishing paints were developed in 1960s. Due to its controlled leaching rate, the self -polishing paints containing TBT was a huge success. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. It was observed that the extensive use of copper based antifouling paints has led to the accumulation of copper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. Foul release coatings are biocide-free –works on a foul release basis by providing a very smooth, low-friction surface which reduce the strength of adhesion of fouling. However, they are applicable only to high- speed, high-activity vessels, in addition to other issues such as high cost, difficult, application procedure and are easily prone to mechanical damage. Biocides from natural products appear to be the only viable alternative in the foreseeable future to protect ship hulls from fouling. This paper reviews the possible natural products that have the potential to be incorporated in to commercial antifouling paints and explores their range of activity"Item Failure analysis of antifouling paints on ships hull(NISCAIR-CSIR, India, 2014-11) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Fouling on ships hull occurs due to the attachment of barnacles, mollusks and other aquatic organisms on the underwater area of the hull. This leads to increased drag, fuel consumption, resulting in unscheduled dry-docking. Recent advances in antifouling (AF) paints, in general, offer protection against fouling in about 95 % of the vessels immersed surface. However, the remaining area which amounts to 5% or less of the total area does get fouled. Although this level of fouling has marginal impact on the routine performance of the vessel, it is a predominant vector for the transmigration of invasive species which is a serious environmental concern. Virtually all ocean going vessels are coated with antifouling paints, predominant among them are “Self polishing coatings”. These coatings depend on the shear forces on the hull surface caused by the motion of the vessel for the paint to “polish” away and release a biocide at a predetermined rate that results in the hull to be essentially fouling free. Currently hulls are coated with a uniform layer of antifouling paints. However, computational fluid dynamics (CFD) analysis conducted on various types of vessels have indicated that there are certain “hotspots” where shear stresses and therefore the polishing rates are exceedingly high which would polish the AF paints at a much faster rate and ultimately result in the failure of the AF coating. The analysis also indicates that these hotspots primarily depend on the profile of the vessels, its speed and its draft. The current practice of a uniform coat of AF paint does not take into account the fact that there are certain areas of the vessel where the polishing rates are excessive. A possible solution to this issue is to first identify these hotspots and suitable paint schemes/formulations are to be applied in these areas. Such painting schemes would prevent the premature failure of the AF coating in general and significantly reduce the risk of transmigration of invasive species.Item Environmentally friendly antifouling paints and painting schemes(International Journal of Innovation Research & Development, 2012-12) Joshi, Madhu; Mukherjee, A.; Misra, S. C.; Ramesh, U. S.Since the 1970's Tributyl tin based antifouling paints were widely used to control fouling on ships hulls. These coatings offered up to 5 years of foul-free hulls and were the most effective antifouling paints ever produced. However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success. However, the extensive use of copper based antifouling paints has led to the accumulation of cooper and its compounds in the marine environment particularly in the vicinity of ports and harbors and is beginning to pose a serious environmental problem. This paper explores the possibility of incorporating environmentally friendly biocides in antifouling paints that exhibit a low persistence in the marine environment particularly those biocides that are available in the Indian context. Another serious problem facing the marine environment is the issue of Invasive species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of non indegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupts the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. Although this fouling does not affect the overall performance of the vessel, would however, be a vector for the transportation of Invasive species. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper attempts to identify such areas using CFD simulations and suggest that special paint schemes must be incorporated in these niche areas.Item Control of biocorrosion to prevent the propagation of invasive species(Indian Maritime University, Chennai, 2010-09) Joshi, Madhu; Mukherjee, A.; Ramesh, U. S.; Misra, S. C.Biocorrosion or biofouling on ships hull occursdue to the attachment of barnacles, mollusks and other aquatic organisms on the surface of ships which leads to increase in fuel consumption, reduction of the vessels speed, premature failure of the hull, etc. Recent developments in antifouling paints, in general, prevent fouling in about 95% percent of the vessels underwater surface, which ship operators find satisfactory as far as the routine vessel operation is concerned. However, this is not sufficient to prevent the transport or invasion of alien species. In recent years the issue of invasive marine species has been receiving considerable attention due to the fact that introduction of nonidegenous species or non-native species transmigrated from other areas to coastal waters often results in the reduction and even extinction of the native species and thereby severely disrupting the natural marine ecosystems. The predominant vector for the transport of nonindigenous species in marine environments has been shipping. While ballast water receives the most attention, hull fouling is now considered to be the most significant means for translocation of these organisms. For example, 90 percent of the 343 marine alien species in Hawaii are thought to have arrived through hull fouling Certain niche areas of the vessel such as bow thrusters, sea chest, stern tube, rudder etc. are the likely areas to be heavily fouled. In addition, the other areas that are likely to be fouled are on locations where antifouling paint has been worn of due to excessive shear and bending of the hull. This paper reviews the various antifouling strategies and aims identify areas on the hull surfaces of certain classes of vessels that are prone to fouling by excessive shear and bending and identify suitable antifouling treatments to further reduce the risk of transportation of alien species.