Fe3＋ coordinated to amino-functionalized spherical mesoporous silica: Preparation, characterization, and application as a rapid and efficient adsorbent for As(V) removal

A facile hydrothermal synthetic method was employed for the preparation of Fe3＋ coordinated to amino-functionalized spherical mesoporous silica (Fe–NH2–SMS), aimed at the rapid and efficient removal of As(V) from water. The morphology, structure and properties of the adsorbent were characterized via SEM, EDS, N2 adsorption–desorption, FT-IR, zeta-potential and XPS. Fe–NH2–SMS exhibited a high performance for As(V) removal with a very fast adsorption rate (reaching equilibrium within 1 min). As(V) adsorption on Fe–NH2–SMS was better fitted to the Langmuir isotherm model (R2=0.988). The maximum adsorption capacity was 43.34 mg g–1 As(V) at 25 °C. The optimum pH for As(V) adsorption was in the range of 5–10. The individual presence of SO42–, SO32–, HPO42– and CO32– had a negative effect on As(V) adsorption. The removal of As(V) via Fe–NH2–SMS in real water samples remained above 95% with an increasing adsorbent dosage up to 1.6 g L–1. Reusability studies indicated that the removal of As(V) was still up to 76% after five adsorption–desorption cycles. Electrostatic attraction and inner-sphere complexation between As(V) and functional groups (–NH2 ⋅ ⋅ ⋅Fe3＋) were identified as the adsorption mechanisms of As(V). The prepared adsorbent can be considered a promising adsorbent for the rapid adsorption of As(V) from water.