The Production and characterization of alginate from Sargassum wightii Greville ex J. Agardh.: Exploring diverse acid treatments and analytical techniques

Abstract

Alginate is a naturally occurring polysaccharide polymer having very distinct and useful characteristics feasible across multiple sectors including agriculture, food, textile and pharmaceuticals serves as an emulsifier, film former, thickener, stabilizer, viscosifier, gelling agent, and therapeutic agent. The seaweed Sargassum wightii (Phaeophyceae) sourced from the Gulf of Mannar was utilized to produce sodium alginate. The seaweed underwent treated with five different acids: H2SO4, HCl, CH3COOH, HNO3, and C6H8O7 to achieve the high-quality alginate, with sulfuric acid yielding the highest at 401±13.11 mg/g. The FTIR and 1H NMR spectroscopic studies were elucidated the chemical properties of extracted alginates. The FTIR results revealed the presence of -OH, O-C-O, C-OH, and C-H groups in the extracted alginate samples. 1H NMR spectroscopic studies revealed the composition of mannuronic and glucuronic acid residues, with acetic acid accounting for the high M/G ratio of 0.85. Additionally, the DLS spectroscopy was employed to determine the particle size, polydispersity index and scattering index of alginate samples, and TGA analyses revealed that extracted alginate samples exhibit good thermal stability, with citric acid representing the highest.