Choline chloride-based solvents as alternative media for alginate extraction from brown seaweed

This study demonstrated an effective method for extracting alginate from the brown seaweed Ascophyllum nodosum using deep eutectic solvents (DES), achieving a higher yield than traditional alkaline extraction methods. Eight choline chloride-based DESs were tested, with DES ChCl:Urea (1:2) yielding the most alginate. The extraction conditions were optimized using response surface methodology (RSM), which identified the biomass to liquid ratio as the most significant factor influencing extraction efficiency. The optimized parameters resulted in a 74% extraction efficiency of alginate. Characterisation through FT-IR and size exclusion chromatography showed that the extracted alginate was comparable to that obtained via the conventional alkaline extraction method. Overall, DES extraction offers a more efficient and sustainable alternative to conventional methods, which typically extract only 10%–24.5% of total alginate.