Synthesis of Sulfate Chitosan using a Sulfuric-Acid Method Based on Chitosan Obtained from Non-Commercial Artemia parthenogenetica Cysts from the Aral Sea

The study reports the synthesis and physicochemical characterization of sulfated chitosan (SCh) obtained from chitosan isolated from non-commercial Artemia parthenogenetica cysts of the Aral Sea using a sulfuric acid-mediated sulfation method. The obtained SCh was a dark-brown powder containing 9.21% sulfur and exhibiting a degree of substitution of 22.0%. Elemental analysis and FTIR spectroscopy confirmed the incorporation of sulfate groups into the chitosan structure. Characteristic sulfate-related absorption bands were observed at 1032 and 1385 cm⁻¹, corresponding to O–S–O and sulfate-group stretching vibrations, respectively. Size-exclusion chromatography revealed that the obtained SCh consisted predominantly of low-molecular-weight fractions of approximately 1.0 and 3.0 kDa, indicating partial degradation of the chitosan chains under the acidic conditions of the sulfation process. The obtained results demonstrate the feasibility of producing low-molecular-weight SCh from non-commercial Artemia parthenogenetica cysts of the Aral Sea.