Mesoporous polyvinylpyrrolidone (PVP)/SiO2 composite nanofiber membranes functionalized with thioether groups have been fabricated by a combination method of sol-gel process and electrospinning. The precursor sol was synthesized by one-step co-condensation of tetraethyl orthosilicate (TEOS) and 1,4-bis(triethoxysilyl)propane tetrasulfide (BTESPTS, (CH3CH2O)(3)Si(CH2)(3)S-S-S-S(CH2)(3)Si-(OCH2CH3)(3)), with the triblock copolymer poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (P123, EO20PO70EO20) as template. After the addition of PVP, nanofiber membranes were prepared by electrospinning. The membranes were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), N-2 adsorption-desorption isotherms, and an Elementar Vario EL analyzer. The composites were used as highly selective adsorbents for Hg2+ due to the modification with thioether groups (-S-), and were conveniently separated from the waste water. The composite could be regenerated through acidification. (C) 2010 Elsevier Inc. All rights reserved.