Preparation of Reed Hemicelluloses-based Hydrogels and its Highly Effective Adsorption of Heavy Metal Ions
2015, 35 (4):
Reed hemicelluloses-based hydrogel was prepared by free radical polymerization using acrylic acid(AA) as monomer and N, N, N', N'-tetramethylene ethylene diamine(MBA) as crosslinking agent. The chemical structure was characterized by FT-IR and the adsorption of heavy metal ions(Pd2+, Cd2+, and Zn2+) was also investigated. The effects of AA and MBA dosages, pH value, contacting time, and initial concentration of metal ion on the adsorption capacity were studied. At the same time the adsorption kinetics and adsorption mechanism of metal ions were discussed. The results showed that the adsorption capacity was influenced by AA and MBA dosages and pH value, and increased with the increase of pH value. The adsorption equilibrium time was approximately 60 min when the hemicellulose was 1.0 g, MBA was 0.1 g, and AA was 9 g. The maximum adsorption capacities of Pd2+, Cd2+, and Zn2+ were 699, 521, and 265 mg/g, respectively. The adsorption process was an ion-exchange mechanism. This suggested that the adsorption kinetics fitted the pseudo-second-order model and the adsorption followed the Langmuir model. Furthermore, reed hemicelluloses-based hydrogel also exhibited highly efficient adsorption of metal ions after 8 repeated adsorption/desorption cycles as the adsorption capacity of Pd2+, Cd2+, and Zn2+ were 616, 479 and 243 mg/g, and the recovery of Pd2+, Cd2+, and Zn2+ were 96.7%, 97.1% and 97.6%, respectively.
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