Solution properties of cellulose sulfate in [Emim]Ac and shaping into composite absorbent materials

Solution properties of cellulose sulfate in [Emim]Ac and shaping into composite absorbent materials
Wenqian Li^a, Zhaomei Wang^*a, Manfeng Li^a
aSchool of Food Science & Engineering, South China University of Technology, Guangzhou, Guangdong Province, 510640, P.R. of China


^*Correspondence should be addressed to ZW (Tel: [phone]; Email: [e-mail])


Abstract
Cellulose sulfates (CS) with varied degree of substitution (DS) were prepared via sulfating modification, resulting in an enhanced solubility in the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim]Ac). CS having DS of 0.42 with solubility of 14.7 g/100g in [Emim]Ac was selected for rheological measurements furtherly. The exponents of specific viscosity versus CS concentration for dilute, semi-dilute disentangled and entangled regimes showed similar values of polymers in a θ solvent. Meanwhile, CS-[Emim]Ac showed a typical property of a polyelectrolyte solution according to the overlap concentration (c*) 0.2 wt% and the entanglement concentration (c_e) 3.0 wt% respectively. The activation energy analysis indicated that the stability of CS-[Emim]Ac solution was highly dependent on temperature. CS-[Emim]Ac solution with concentration 5 wt% was mixed with chitosan in 1:1 (w/w) to produce composite beads (22.1 µm) and magnetic microsphere (1.0 µm) by ball dropping and emulsification-solvent evaporation methods, respectively. The magnetic microsphere showed remarkable adsorption capacity for bovine serum albumin owing to the particle size effect as well as the synergistic effect of nano Fe₃O₄ with the maximum adsorption value of 780 mg/g.
Keywords: Cellulose sulfate, Ionic liquids, Solution property, Adsorption