Microwave Assisted Extraction of Raw Alginate as a Sustainable and Cost-Effective Method to Treat Beach-Accumulated Sargassum Algae

Abstract

This paper highlights the potential of Sargassum algae, recovered from raw beach seaweed wastes, as a valid source of valuable sodium alginate. Alginate is a biodegradable, highly attractive polysaccharide widely used in food, pharmaceuticals, and biomedicine applications. The aim of this work is to employ a new eco-sustainable and cost-effective extractive method to obtain alginate as a raw material from pollutant organic Sargassum seaweeds. Algae were exposed to microwave pre-treatment under static and dynamic conditions, and three different extractive protocols were followed: (a) conventional, (b) hot water and (c) alkaline method. All samples were characterized by GPC, SEM, FTIR/ATR and TGA. It was found that alginate’s best performances were obtained by the microwave dynamic pre-treatment method followed by alkaline extractive protocol. Nevertheless, the microwave pre-treatment of algae allowed the easiest breaking of their cell walls and the following fast releasing of sodium alginate. The authors demonstrated that microwave-enhanced extraction is an effective way to obtain sodium alginate from Sargassum-stranded seaweed waste materials in a cost-effective and eco-sustainable approach. They also assessed their applications as mulching films for agricultural applications.

Biosorption of Technologically Valuable Metal Ions on Algae Wastes: Laboratory Studies and Applicability

“…However, in order to avoid the use of organic solvents for the extraction of such active compounds, it is preferred to treat the algae biomass with concentrated alkaline solutions (NaOH or KOH). Concentrated alkaline solutions solubilize the polysaccharides in the cell walls and ionize most of the molecules inside the algae cells, thus allowing the extraction of these active compounds [24]. Algae wastes obtained after extraction are often incinerated or stored because they contain traces of alkaline solutions (even after have been washed several times), which reduces the possibilities of use for other purposes.…”

Alginate Cryogels as a Template for the Preparation of Edible Oleogels

“…Alginate is a naturally occurring polysaccharide found within the cell walls of brown seaweed and holds immense potential in various fields due to its unique properties and versatility [13]. This biocompatible and readily available biopolymer has the ability to form gels in an acidic environment and in the presence of divalent cations.…”