METHODS AND CHARACTERISTICS FOR OBTAINING SULFONATED CELLULOSE USING COTTON LINT

This study presents a controlled synthesis method for sulfonated cellulose (SCel) derived from cotton lint, an abundant agricultural by-product in Uzbekistan. By systematically varying the molar ratio of sodium bisulfite to anhydroglucose units (AGU), reaction temperature, and duration, a series of SCel samples with a tunable degree of substitution (DS) ranging from 0.15 to 0.65 was successfully produced. The chemical modification and structural evolution were thoroughly investigated using Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance ( NMR, HSQC), X-ray diffraction (XRD), and thermogravimetric analysis (TGA/DTG/DSC). FTIR and NMR analyses confirmed the successful introduction of sulfonate groups (), with primary substitution occurring at the C6 position and secondary substitution at C2/C3 at higher DS levels. XRD results indicated a progressive decrease in crystallinity index from 78% to 41% with increasing DS, reflecting the amorphization of the cellulose structure due to sulfonate group incorporation and hydrogen bond disruption. TGA demonstrated a significant enhancement in thermal stability, with the onset decomposition temperature increasing by up to 30°C compared to native cellulose. The synthesized SCel materials, with tailored DS and improved thermal properties, show high potential for applications in demanding environments, such as high-temperature drilling fluids, adsorbents, and functional polymer composites.