The products of reaction of natural chrysotile fibers with phenylarsonic acid or 2-nitrophenol-4-arsonic acid are described. The new grafted layered materials with basal spacing of 15.5 and 17.0 Angstrom were characterized by powder X-ray diffraction, thermal analysis, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The experimental data are consistent with the grafting of phenylarsonate and 2-nitrophenol-4-arsonate groups onto the surface of the disordered silica, obtained by the in situ acidic leaching of the brucite-like sheets starting from the original chrysotile structure. (C) 2004 Elsevier Inc. All rights reserved.