Abstract: One of the most harmful pollutants to human health present in natural water is arsenic. In this work magnetic silica/magnetite nanoparticles functionalized with aminopropyl groups incorporating Fe3+ (S1-F3) were investigated for their suitability as materials to adsorb As5+ and As3+ from polluted groundwater. Magnetite nanoparticles obtained by a co-precipitation method were coated with a mesoporous silica layer generated by hydrolysis and condensation of tetraethyl orthosilicate. The resultant material was grafted with amino derivatives coordinated with Fe3+. The synthesis was confirmed by FT-IR, TGA and BET analyses. After analysis of the affinity of solids with different degrees of functionalization towards arsenate and arsenite species, the material S1-F3 resulted in maximum arsenic adsorption capacities (14.7?±?0.3?mg As3+g-1 and 121?±?4.1?mg As5+g-1). The adsorption equilibrium was satisfactorily described by the Langmuir model and exhibited low sensitivity to temperatures in the range 288–308K. Kinetic data were correlated with a pseudo-second-order kinetic model based on solid capacity that considers the rate of the surface reaction as the rate-limiting step. The promising results confirm that the material S1-F3 is an effective adsorbent for the removal of arsenate from polluted water. More research is being conducted to analyse the influence of competing anions and sorbent regeneration.

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