Sorbents Based on Highly Dispersed Boehmite Surface-Modified with Phosphonic Complexones: Preparation and Characterization

Abstract—New complexing sorbents have been manufactured via chemical surface-modification of highly dispersed boehmite (γ-AlO(OH)) by phosphonic complexones (PCs), namely, by nitrilotri(methylenephosphonic) acid (NTP), 1-hydroxyethane-1,1'-diphosphonic acid (HEDP), N-hydroxyethylimino-N,N-di(methylenephosphonic) acid (HEIDP), and imino-N,N-diacetic-N-methylenephosphonic acid (IDAMP). The manufactured PC–boehmite materials have been characterized by XRD, BET, SEM, TEM, and IR spectroscopy. Modified boehmites, in which the modifier anchor is one of the phosphonic functions of the complexone, exhibit the properties of a complexing support for double-charged metal ions. The kinetic characteristics and sorption capacities of PC–boehmites have been determined. The complexing selectivity on the modified surface are arranged in the following decreasing order: Pb(II) > Cu(II) > Zn(II) ≈ Ni(II) ≈ Co(II) ≈ Cd(II) > Ca(II). The stability of the sorbed state of metal ions changes along the series of surface-anchored complexones in the following order: IDAMP > NTP > HEDP > HEIDP. The trends elucidated point to a close correlation between complexa formation involving phosphonic complexones in solution and on the boehmite surface.