The original sepiolite clay mineral has been collected from Amazon region, Brazil The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon sepiolite surface by heterogeneous route. The natural (SPT) and modified (SPTAMP) sepiolite samples were characterized by elemental analysis, SEM. N-2 adsorption, and nuclear magnetic nuclei of Si-29 and C-13 The well-defined peaks obtained in the C-13 NMR spectrum in the 0-160 ppm region confirmed the attachment of organic functional groups as pendant chains bonded Into the porous clay The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 40 The maximum number of moles adsorbed was determined to be 726 x 10(-2) and 11 70 x 10 (2) mmol g(-1) for SPT and SPTAMP, respectively In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1 0 g) and it was fed with 20 x 10(-2) mmol dm(-3) As(V) at pH 4.0 The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such As(V)-nitrogen interactions (C) 2010 Published by Elsevier Inc