Periodic mesoporous titanium phosphonate hybrid materials

Abstract

Periodic mesoporous titanium phosphonate materials (PMTP-1) with bridged-organic groups inside the framework are synthesized by an autoclaving process combined with the evaporation-induced self-assembly (EISA) strategy, with the assistance of surfactant Brij 56 (C₁₆EO₁₀). Sodium salt of ethylene diamine tetra(methylene phosphonic acid) (EDTMPS) is used as the coupling molecule. A typical hexagonal mesophase is confirmed by TEM, N₂ sorption and XRD analysis. The organophosphonate groups are homogeneously incorporated in the network of the mesoporous solids, as revealed by FT-IR, MAS NMR, TG-DSC and XPS measurements. The calcination experiments also prove that the hexagonal mesoporous titanium phosphonates are thermally stable up to 450 °C, and then transformed into inorganic hexagonal mesoporous titanium phosphates. The PMTP-1 hybrid materials can be used as useful photocatalysts for organic dye degradation and also as efficient adsorbents for heavy metal ions, which follow Langmuir-type behavior exhibiting innate selective affinity for the adsorption of Cu²⁺ over Pb²⁺ and Cd²⁺ ions, demonstrating their promising potential in environmental remediation.