Valorisation of the

Only a few varieties out of the 12,000 algal species recorded worldwide have been studied in literature to develop green biopolymers. To the best of our knowledge, there are no reported studies so far on alginate biopolymer extraction using Sargassum obovatum (SO). This study therefore reports for the first time the main composition of SO as well as the main alginate characteristics extracted from SO. SO was characterised in terms of moisture, ash, crude fats, crude protein and total carbohydrates using respective standard methods. Sodium alginate was then extracted from dry SO (particle size range: 0.589 – 0.833 mm) using a green acid treatment to determine its maximum crude yield. Finally, the key properties of the extracted sodium alginate were determined in terms of FTIR, viscosity and colour analyses. The high carbohydrates content (50.79%) suggests that SO can be a viable source of alginate. FTIR confirmed that alginate was successfully extracted, and a high crude yield (70.88%) of low-viscosity (4.03 cP) alginate was obtained. SO can thus be collected to extract alginate for use in areas where low-viscosity biopolymers are required, such as biosorbents for heavy-metal adsorption from wastewater effluents, in textile printing or for encapsulation purposes through spray-drying.