Mesoporous silica functionalized with 2-mercaptopyridine: Synthesis, characterization and employment for Hg(II) adsorption

Mesoporous silicas (SBA-15 and MCM-41) have been functionalized by two different methods. Using the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the mesoporous silica surface to give the chlorinated mesoporous silica Cl-SBA-15 or Cl-MCM-41. In a second reaction a multifunctionalized N, S donor compound (2-mercaptopyridine, MP) was incorporated to obtain the functionalized silicas denoted as MP-SBA-15-Het or MP-MCM-41-Het. Using the homogeneous route, the functionalization was achieved via the one step reaction of the mesoporous silica with an organic ligand containing the chelating functions, to give the modified mesoporous silicas denoted as MP-SBA-15-Hom or MP-MCM-41-Hom. When the functionalized mesoporous silicas were employed as adsorbents for the regeneration of aqueous solutions contaminated with Hg(II), mercury adsorption was higher in the mesoporus silicas prepared by the homogeneous method. The modified mesoporous silica MP-SBA-15-Hom displayed the best mercury adsorption efficiency.