UNAM researchers use sargassum for construction

Researchers at the Centre for Applied Physics and Advanced Technology of the National Autonomous University of Mexico (UNAM) are utilizing sargassum, a type of seaweed, in the production of construction panels and biofilters. The goal is to repurpose this marine compound, giving it a “second life”.

Lead researcher, Miriam Estévez, and her team have been conducting laboratory-level investigations on sargassum for over a decade. They’ve found that sargassum contains numerous phytochemicals, including carotenoids such as fucoxanthins, which have various medical applications, including anticarcinogenic properties. The team has also used sargassum extracts for green synthesis.

The researchers aim to address the issue of large amounts of sargassum washing up on Caribbean beaches, by creating a construction material with unique properties. This material can be easily incorporated into current production lines for panels and used to create filters for removing contaminants.

Large quantities of sargassum are shipped from the Institute of Marine Sciences and Limnology of Puerto Morelos, Quintana Roo, to Querétaro. Here, the dried seaweed is treated to remove all contaminants and prevent decomposition before being used by the researchers.

The team has received approximately a ton and a half of sargassum for their prototypes. Each panel requires at least five kilos of dry sargassum, equivalent to 60 kilos of wet seaweed. The panels, made of gypsum, sargassum, and organic fibers, contain no additives. They can be fully recycled, with 60% of the panel being reusable after its lifecycle ends. Furthermore, the panels are highly flexible, fire retardant, and reportedly keep spaces cooler.

The team has also developed biofilters, prototypes containing treated sargassum that can absorb various contaminants. These include colorants, pharmaceutical residues, heavy metals, herbicides, sulfates, phosphates, fats, and oils. These biofilters are more cost-effective than commercial filters, as they repurpose waste into a filtering material. This system could also be adapted to other filtration methods.

In 2023, the Marine Secretariat collected 57,000 tons of sargassum. However, most of this seaweed cannot be collected and ends up on beaches where it decomposes, causing issues such as unpleasant odors and changes in the landscape color. As it decomposes, it consumes large amounts of oxygen, leading to anoxia and the emission of toxic gases.

The sargassum-based panel and biofilter are not yet available for sale, and their cost has not been determined. The researchers believe that the panel will be competitive against other products on the market. It meets all ASTM standards for construction but is handmade rather than mass-produced. Despite this, researcher José Luis López Miranda from UNAM believes that the product will be affordable once regulations are in place.