Natural biocides in antifouling paints

Abstract

Since the 1970’s Tributy tin based antifouling (AF) 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 However, due to serious environmental effects, these paints have been banned since 2008 and have been replaced by copper based antifouling paints with some success.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 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. Restrictions on the use of copper based AF paints have been initiated by many western countries and it is expected that these restrictions would only grow in the years to come. In addition, these coatings are usually incorporated with “booster biocides” such as Diuron, Irgarol, Seanine, etc to improve their efficacy. The booster biocides also significantly contribute to the existing environmental concerns. The search is therefore on for a “benign AF product” that affects target organisms only and exhibits low persistence in the aquatic environment. A few natural produces fill in to these requirements. In the Indian context, Neem and Karanjin exhibit biocidal properties which could be tapped as effective AF agents. This paper reviews the various natural products that show promise as AF agents and explores the possibility of incorporating these products in AF paint formulation.