Polymeric hydrogels obtained using a redox initiator: Application in Cu(II) ions removal from aqueous solutions

摘要

Poly(acrylic acid-co-acrylamide) hydrogels were prepared via free-radical solution polymerization, crosslinked with ethylene-glycol-dimethacrylate, potassium persulfate/ammonium bisulfite as the initiator, and applied in the removal of Cu(II) ions from aqueous solutions. Molar ratios of acrylamide/acrylic acid moieties and the amount of crosslinking agent were varied to determine the swelling capacities of hydrogels and maximum metal uptake. Polymerization kinetics was investigated by ~1H-NMR. Hydrogel physicochemical properties were characterized by nitrogen sorption measurements, elemental analysis, FTIR, and X-ray photoelectron spectroscopy (XPS). Swelling results indicated that hydrogels were swollen up to 27,500%. Hydrogels showed equilibrium Cu(II) adsorption capacities of 211.7 mg g~(-1) and fast kinetics (～20 min). Langmuir isotherm fitted adsorption equilibrium data. FTIR and XPS results helped in elucidating the presence of monodentate copper complex on the surface of hydrogels. A simple synthesis route of hydrogels using the redox initiator suggests the potential application in the removal of toxic metals from aqueous streams.