Covalent surface modification of α-MnO2 nanorods with l-valine amino acid by solvothermal strategy, preparation of PVA/α-MnO2-l-valine nanocomposite films and study of their morphology, thermal, mechanical, Pb(ii) and Cd(ii) adsorption properties

Abstract

The surface of α-manganese dioxide (α-MnO₂) nanorods was modified chemically with L-valine amino acid by a solvothermal strategy. The α-MnO₂ nanorods were prepared by a hydrothermal method. Then poly(vinyl alcohol)/α-MnO₂-L-valine nanocomposites (NCs) containing 1, 3 and 5 wt% of modified α-MnO₂ nanorods were prepared through an ultrasound-assisted technique. Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and UV-visible spectroscopy were used to investigate and characterize nanostructures and NCs. Following this, the effects of α-MnO₂-L-valine nanorods on the properties of NCs, such as the mechanical and thermal properties, were studied. The Brunauer–Emmett–Teller (BET) results showed that NC 3 wt% had higher surface area, pore volume and pore size than pure PVA with mesoporous structure. Finally, NC 3 wt% was investigated as an adsorbent for sorption of Pb(II) and Cd(II) ions. It showed good adsorption potential for the removal of Pb(II) and Cd(II) in aqueous solution.