Kinetic and Isotherm Studies of Ni2+Adsorption on Poly(methacrylic acid) Synthesized through a Hierarchical Double-Imprinting Method Using a Ni2+ Ion and Cationic Surfactant as Templates
journal contributionposted on 2013-06-26, 00:00 authored by Fernanda Midori de Oliveira, Bruna Fabrin Somera, Emerson Schwingel Ribeiro, Mariana Gava Segatelli, Maria Josefa Santos Yabe, Evgeny Galunin, César Ricardo Teixeira Tarley
A novel poly(methacrylic acid) material (IIP/CTAB) was prepared by a hierarchical double-imprinting process with Ni2+ ion and cationic surfactantcetyltrimethylammonium bromide (CTAB) as templates, and it was employed to adsorb Ni2+ ions from aqueous medium. Other poly(methacrylic acid) materials single-imprinted (IIP/no CTAB) and nonimprinted (NIP/no CTAB) were investigated in adsorption studies. All the synthesized polymers were characterized by FTIR, SEM, and nitrogen adsorption–desorption isotherm. The maximum Ni2+ adsorption capacities of IIP/CTAB and NIP/no CTAB were found to be 33.31 and 18.64 mg g–1, respectively, at pH 7.25. The relative selectivity coefficient (k′) values for Ni2+/Cu2+, Ni2+/Mn+, Ni2+/Co2+ and Ni2+/Pb2+ systems were higher than 1, thus confirming the significant improvement in the selectivity of the polymer. The kinetic data were described very well by the pseudo-second-order model, thereby confirming the chemical nature of the Ni2+ adsorption (chemisorption), whereas the dual-site Langmuir–Freundlich equation provided the best fit to the isotherm data, suggesting the existence of two kinds of adsorption sites (with low and high binding energies) on the polymer surface. The high chemical stability of IIP/CTAB was verified with 300 Ni2+ adsorption–desorption cycles using 1.0 mol L–1 HNO3 as stripping agent.