Sargassum, a type of large brown seaweed, has been in the news lately, with a massive blob that’s visible from space and threatening ocean life. A recent grant from the U.S. Environmental Protection Agency is funding research at Florida Tech that could address the issue, while also helping solve another problem in our water.
Toufiq Reza, an assistant professor of chemical engineering in the Department of Biomedical and Chemical Engineering and Sciences, along with research students Cadianne Chambers, Swarna Saha, Savannah Grimes and Josh Calhoun, were part of the research paper, “Physical and morphological alteration of Sargassum‐derived ultraporous superactivated hydrochar with remarkable cationic dye adsorption.” The paper was published in the May edition of Springer Nature’s Biomass Conversion and Biorefinery journal.
The paper is part of a three-year, nearly $400,000 EPA grant to examine different uses of sargassum. It explains that the team can produce biochar from sargassum that can filter water. Though the team has tested model dye in this paper, they plan to extend their research for other applications including harmful algal bloom remediation and nutrient recovery in the future.
While sargassum has been around for centuries (Christopher Columbus is credited with the first written account after he encountered it in 1492), and you’ve probably seen bits of brownish seaweed on the beach – it sometimes smells like rotten eggs – the quantities in the ocean and washing up on shores are a more recent phenomenon. There are multiple reasons behind the increased amount of sargassum, including global warming that intensifies sargassum production and nutrient runoff making its way to ocean water and overfertilizing the seaweed growth.
More sargassum is expected to show up on Florida shores in the future, inspiring the team to explore more positive uses of the abundant seaweed.
“In the next couple of years, we’ll be seeing much more sargassum coming into our way. It’s not a common practice to utilize sargassum,” Reza said. “We go to a beach and then we see a little bit of sargassum just dried out. That doesn’t bother us that much, but when it started to come as a foot-tall sargassum wave, that’s where it gets more alarming.”
Sargassum in the lab is labor intensive. Because it contains salt from the ocean, it is washed with tap water first, then put in a freezer for preservation. Next, it goes through hydrothermal carbonization, a thermochemical process that uses heat and pressure to convert biomass and organic waste (such as the sargassum being used) into solid hydrochar. Lastly, the solid char goes through pyrolysis, where it is heated in a high-temperature, oxygen-free chamber into a biochar that is used to filter water.
For Swarna Saha, a first-year doctoral student, her goal as a researcher is to identify an environmental problem and come up with a sustainable solution. Having grown up in Bangladesh around textile factories that generate dyes that pollute the surface water, she was inspired to work on solutions that improved water quality with biochar.
“I came in the project when we were experimenting on dye adsorption and saw how a tiny amount of biochar changes the color of the water,” she said. “For me, seeing the results made me the happiest. When we saw that our biochar is effective, that is the biggest achievement for me. That made me happy.”
Cadianne Chambers, a second-year doctoral researcher, was motivated by her home country of Jamaica and its massive issues with sargassum. Chambers has heard accounts of fishermen unable to go out to sea because of the sargassum buildup. A popular destination for summer vacation, Jamaica is facing serious environmental and economic problems with waves of sargassum.
“A team in Jamaica saw that article and they reached out to us, and they’re trying to cultivate sargassum. They want us to teach them how to make export-quality hydrochar and biochar, which could help solve their environmental problem and generate revenues,” Chambers said. “So, everything is just connecting nicely and I’m hoping to continue our collaboration with them. If it’s something that I can go home and put my PhD research to work and help the community, that would be really satisfying.”