Phosphine-functionalized PVA/SiO2 (Pgf-PVA/SiO2) composite nanofiber adsorbent (porous) was prepared using a facile electrospinning technique. The successful fabrication of the pgf-PVA/SiO2 nanofibers was confirmed by field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analyses. The nanofiber adsorbent was evaluated for water sensitivity, N-2 adsorption-desorption isotherms, pore size distribution, and manganese (Mn+2) and nickel (Ni+2) ions removal from aqueous solution at various pH, contact times, and adsorbent dosages as well as at different regeneration/reuse cycles. The composite pgf-PVA/SiO2 nanofibers (with 0.5 g/L fiber loading) can remove almost completely (96-98%) the aforementioned ions from aqueous solutions (initial concentration of 120 mg/L, pH 6) within 15 min of contact time. A reasonably simple acid treatment (with a 1 M HCl solution) was found to be extremely effective in regenerating the nanofiber adsorbent, and 92.5% of the metal ions were removed from the adsorbent even in the fifth regeneration/reuse cycle. Additionally, the adsorption equilibrium studies revealed the excellent adsorption capacities of the pgf-PVA/SiO2 nanofiber for both Mn+2 and Ni+2 ions (234.7 and 229.9 mg/g, respectively). (C) 2015 Elsevier B.V. All rights reserved.