A Lignin-containing Hemicellulose-based Hydrogel and its Adsorption Behavior

A lignin-containing hemicellulose-based hydrogel was prepared from acylated hemicellulose and acrylic acid by free radical polymerization reaction, initiated by ammonium persulfate and N,N,N',N'-tetramethyl-ethane-1,2-diamine in the presence of sodium lignosulfonate. Sodium lignosulfonate present in the hydrogel, when grafted by poly(acrylic acid), was identified as an interpenetrating polymer network form, while that not grafted by poly(acrylic acid) was identified as a semi-interpenetrating polymer network form. Both the swelling ratio and the adsorption capacity were dependent on sodium lignosulfonate dosage. The adsorption behavior of the hydrogel was evaluated. The maximum adsorption capacity towards methylene blue, a model dye, was 2691 mg/g. The adsorption kinetics and isotherm were well fitted by pseudo-second-order kinetics and Langmuir isotherm model, respectively. The hydrogel reveals an approximately 80% adsorption efficiency after fourth recycle. This hydrogel is a promising material for dye wastewater treatment.