Modified tannin extracted from black wattle tree as an environmentally friendly antifouling pigment

- The use of modified black wattle tannin as antifouling pigment was investigated.
- 13C NMR analysis confirm the modification of tannin (cleavage of interflavonoid bond).
- Immersion tests shows the high antifouling efficiency of TAN coating until 7 months.
- The use of tannin can eliminate the release of toxic biocides to the environment.

The use of modified black wattle tannin as an antifouling pigment is reported in this work. A mixture of tannin adsorbed in activated carbon (soluble fraction of tannin) and low soluble fraction of tannin was used as an antifouling pigment. The soluble rosin resin was used as a paint matrix. 13C NMR analysis confirm the modification of black wattle tannin through the cleavage of tannin interflavonoid bonds. FTIR spectra indicate the presence of tannin in the formulated antifouling coating even after 7 months of its exposure in a marine environment. Water contact angle analysis shows the hydrophilic characteristic of the tannin antifouling coating surface. Immersion tests at Badalona Port in the Mediterranean Sea shows the high antifouling efficiency of the TAN coating, comparable to commercial paint, until 7 months. The use of a natural black wattle tannin, without its complexation with metals, can eliminate the release of metals and other toxic biocides to the marine environment.