Evaluation of tannin from Rhizophora apiculata as natural antifouling agents in epoxy paint for marine application

•We investigate the potential of tannin in mangrove bark as antifoulant agent.•We improve a commercial epoxy paint to become an antifouling paint.•Increasing quantity of tannin will increase the antifoulant performance.•The mangrove bark extract was sensitive to all the target bacteria. Development of non-toxic or less toxic paints has become a target for researchers due to the awareness of the impacts from the use of toxic antifouling paints. One of the modern alternatives to produce an environmental friendly paint is by using natural products. This study investigated the mangrove, Rhizophora apiculata tannin derivatives (zinc tannate) for antifouling properties by incorporating the powdered extract with different amount in epoxy paint formulation. The antifouling activity of zinc tannate was proved by antifouling crystal violet assay and the specimens have been exposed in seawater environment. The initial and final weights of mild steel were recorded to obtain the mass accretion which indicates the weight of biofouling settlement over the specimen surface. The effectiveness of this antifouling agent depends on the amount of zinc tannate in the paint and their leaching rate in seawater. Low concentration of zinc tannate (2.736mg/ml) was found sufficient to inhibit the growth of bacteria, Bacillus cereus.