Synthesis of hydrogel from sugarcane bagasse extracted cellulose for swelling properties study

Insolubility of cellulose in common solvent had been a challenge in generating cellulose hydrogels. In the present work, hydrogels from sugarcane bagasse extracted cellulose and modify with synthetic polymer, poly (vinyl alcohol) (PVA) and cross-linker, glutaraldehyde (GA) was synthesize. Cellulose was isolated from sugarcane bagasse via pre-treatment with 4 vol% sulphuric acid (H2SO4) and 10 wt% sodium hydroxide (NaOH) solution. The cellulose extracted was dissolved in ZnCl2/CaCl2 solution at 65 ℃ to fabricate self-standing cellulose hydrogel without cross-linker. Another cellulose hydrogel was generated and immersed into 5 wt% GA solution to cross-link the cellulose chains. To improve the stability and swelling properties of cellulose, PVA was introduced into the hydrogel by using GA to cross-link cellulose chains with PVA chains. The resulting hydrogels were characterized with Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy and solid state 13C Nuclear Magnetic Resonance (NMR) spectroscopy for structural determination. Three self-standing cellulose-based hydrogels, including regenerated cellulose (RC), GA cross-linked cellulose (C-GA), followed by PVA and GA cross-linked cellulose (C-GA-PVA) were successfully generated from ZnCl2/CaCl2 dissolution system and each hydrogel possessed different physical aspects. The occurrence of chemical cross-linking reaction between cellulose, GA and PVA was further evidenced by the data analyzed from ATR-FTIR and NMR spectra. The swelling degree of hydrogels generally increase after the addition of PVA and GA into cellulose suspension, showing 52 % (RC), 80 % (C-GA) and 135 % (C-GA-PVA). C-GA-PVA possessed the best swelling capability and potential for possible application as water reservoir in agriculture.