Have you ever observed the attachment of an animal to a ship’s hull? Animals such as shells, barnacles, gravestones, and snails can stick to the hulls of ships or other structures around the harbor, forming a crust that is difficult to clean.
This condition is called biofouling, which has a very detrimental impact. Because, in addition to physically destroying the structure, the accumulation of these animals can also slow down the ships because it increases the weight of the ship and add more friction with water. As a result, ships need more fuel to reach normal speeds to compensate for the presence of the crust.
This problem inspired two students from Indonesia to look for materials that could overcome them. I Made Wiratathya Putramas and Carolline Mathilda Nggebu, developed antifouling paint, which can prevent animals attaching to ships.
This paint is based on leaf extract obtained from two species of mangrove plants, Rhizophora apiculata and Sonneratia alba.
“From the sources we read, journals and articles, the two types are the most potential because they contain active compounds needed to prevent biofouling,” said the two young researchers.
They also explained that these two mangrove species were very abundant and easily found on the coast.
Natural Anti-Biofouling Paints
The process of making antifouling paint consists of several stages.
The first stage was collecting leaves from both mangrove species, followed by maceration (extracting the active compound from the sample) using three different organic solvents, namely n-hexane, isopropyl alcohol, and methanol.
Next is a series of tests on the active compounds, including phytochemical tests, Fourier-Transform Infrared Spectroscopy (FTIR) analysis, and Gas Chromatography Mass Spectrometer (GCMS) analysis.
After that, the effect of active ingredient extracts was tested on the ability of Pseudomonas aeruginosa and microfouling of sea snail Littorina scutulata.
This active ingredient is then formulated as a paint mixture, which is then carried out field tests for its use directly on ships. The result, it was seen that the extracts of the two mangrove plants had the ability to inhibit the attachment of organisms, both microfoulers such as bacteria, and macrofoulers such as sea snails.
This is because in the two leaves of the mangrove plants, there are alkaloid compounds, flavonoids, saponins, tannins, quinones, and triterpenoids that protect the surface of the ship from the accumulation of bacteria which can lead to accumulation of other organisms.
Previously, most antifouling paints used tributyltin (TBT) compounds. However, this compound is toxic and can endanger the population of shellfish and other mollusks. The findings of this environmentally friendly mangrove leaf extract are expected to be a solution to these problems.
This research made the two students win the 4th ISEF 2019 Intel Grand Award in Phoenix, Arizona, for the Earth and Environmental: Life Sciences category. Their scientific work is entitled Potential Identification and Application of the Rhizophora apiculata and Sonneratia Alba as Bio Antifouling Agent for Antifoulant Paints.
However, they say that there are still many things that need to be improved and refined to improve the effectiveness of this formula. “There is a lot that needs to be improved and done so that bio-antifouling is effective and ready to be marketed. The extraction method, for example, can be modified with solvents or different methods, ” as said by Made.
They still need to identify the compounds that most play a role in antifouling and how to obtain them, so that later other compounds can be disposed of so that they are not mixed in paint. Meanwhile, for general marketing and use, further field testing is needed to determine paint performance in the long run.