New Functionalized Magnetic Materials for As5+ Removal: Adsorbent Regeneration and Reuse

The presence of arsenic in natural water is one of the most important pollution problems worldwide. Functionalized magnetic silica/magnetite nanoparticles (M3) have been reported as effective materials for arsenate adsorption [Saiz et al., 2014]. Because the process economy might be limited by the solid reuse, this work aims at the analysis of the regeneration and reusability of arsenate loaded M3 materials. The influence on the desorption and readsorption efficacies of the type and concentration of the regeneration agent, HCl or NaOH, and the sorbent refunctionalization steps (F1 is protonation of amino groups, F2 is coordination of Fe3+) is analyzed. Desorption with HCl is concentration dependent with maximum efficacies at 0.25 mol L–1. Solutions of NaOH 10–3 mol L–1 provided the best desorption performance; however, the regeneration of the solid needed of two stages of refunctionalization (F1 and F2). Furthermore, regenerated materials under alkaline conditions reported adsorption yields of arsenic around 90%.