Poly(methacrylic acid)-graft-Ni3Si2O5(OH)4 multiwalled nanotubes as a novel nanosorbent for effective removal of copper(II) ions

Abstract

Abstract Ni 3 Si 2 O 5 (OH) 4 nanotubes (NTs) are synthesized by a facile one-pot hydrothermal reaction, and further functionalized by grafting of poly(methacrylic acid) (PMAA) brushes via distillation-precipitation polymerization. The resultant PMAA-grafted NTs are used as a novel nanosorbent to uptake copper(II) ions. Success in each functionalization step is ascertained by the characterization of TEM, FTIR, XPS, SEM and TGA. Batch adsorption results indicate that the adsorption of the pristine and PMAA-grafted silicate NTs is fairly fast and the equilibrium is established within 20 min, and the kinetics follow the pseudo-second-order mechanism, evidencing chemisorption as the rate-limiting step. The best interpretation for the equilibrium data is given by Langmuir isotherm, and the maximum adsorption capacity is 2.13 mmol g −1 (136 mg g −1 ) at pH 5 and 25 °C. The successive adsorption-desorption studies reveal that the PMAA-grafted silicate NTs are readily regenerated, and keep their adsorption and desorption efficiencies constant over five cycles. The Ni 3 Si 2 O 5 (OH) 4 - g -PMAA NTs could be directly reduced via hydrothermal reaction to achieve magnetic property for easy separation. With the inherent advantages of pH-sensitivity of PMAA, large surface area and magnetic properties of Ni 3 Si 2 O 5 (OH) 4 NTs, the PMAA-grafted silicate NTs offer a promising and highly efficient nanocomposite sorbent to remove heavy metal ions from aqueous solution.