Extraction and characteristic properties analyses of sodium alginate derived from the Sargassum oligocystum brown seaweed alga of the Bay of Bengal

Sodium alginate extracted from Sargassum oligocystum brown seaweed alga is an important blue economy development process of the Bay of Bengal. In the present study, sodium alginate was extracted from the brown seaweed alga collected from the Cox’s Bazar coastal area of the Bay of Bengal. The extracted product was characterized with the Ultraviolet-visible (UV–visible) spectrophotometer, Fluorescence spectrophotometer, Fourier transform-infrared radiation (FT-IR) spectrophotometer, X-ray diffractometer (XRD), and Scanning electron microscope (SEM). The product yield was optimized with different pH levels and the maximum yield was obtained at 32.5 % at pH 10.96. The moisture, and ash content of the extracted product was measured and found at 13.25 % and 4.35 %, respectively. The viscosity of the extracted product was obtained at 60.1 mPs. The UV–visible spectrophotometry showed different absorbance peaks found at 234 nm, 240 nm, 250 nm, and 264 nm which assigned the extracted product of sodium alginate, and the maximum absorption peak lies at 276.7 nm which assigned flavonoids, and their derivatives of alginates. The fluorescence spectrophotometry demonstrated a strong emission peak at 460 nm with higher intensity (200), indicating the presence of sodium alginate. The FTIR showed the characteristic peaks that demonstrated different functional groups of sodium alginate. The XRD pattern demonstrated 0.24 crystalline indexes indicating the semi-crystalline product in nature. SEM showed clear fibrils of sodium alginate morphology indicating the absence of impurity materials.