Removal of Cu(II), Ni(II) and Zn(II) from aqueous solutions using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) gel: sorption kinetics and characterization

Removal of Cu(II), Ni(II) and Zn(II) ions from aqueous solutions was studied by using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) gel. The gel was prepared by free radical polymerization at 60 degrees C for 24 h in the presence of the ammonium peroxodisulfate and N, N'-methylenebis( acrylamide) as the initiator and the cross-linker, respectively. The effect of initial metal ion concentration (25-100 mg/L) on the removal efficiency and the sorption process were investigated by batch method. At initial concentration of 25 mg/L, the removal efficiencies were found to be higher and too close to each other (95%-95.5%), whereas lower removal efficiencies (65.8%-72.0%) were determined at an initial concentration of 100 mg/L, for all the metal ions investigated. Sorption data of Cu(II), Zn(II), and Ni(II) ions on the gel showed good fit to the pseudo-second order type kinetics. PAMPS exhibited slightly higher selectivity for the sorption of Zn(II) from ternary solutions at higher concentrations. Characterizations of the poly(2-acrylamido-2-methyl-1-propanesulfonic acid) gel before and after the sorption process were carried out by Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), environmental scanning electron microscopy (ESEM), and zeta (zeta) potential measurements. PAMPS gel was found to be charged negatively at pH values between 3 and 9.