Ordered Macroporous Titanium Phosphonate Materials:  Synthesis, Photocatalytic Activity, and Heavy Metal Ion Adsorption

A three-dimensionally ordered macroporous titanium phosphonate material (TOP) was synthesized by an inverse opal method using 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP). The β-cyclodextrin (β-CD)-added derivative (TOPβ) with hydroxy ethylidene groups inside the frameworks was also performed, having morphology modification and catalytic and adsorptive ability improvement. The samples were characterized by SEM, TEM, XRD, TG-DTA, FT-IR, and UV-vis absorption spectroscopy techniques. The introduced macroporous structure and the presence of the phosphorus and organic groups within the titanium phosphonate framework are believed to contribute the improvement of photocatalytic activity and heavy metal ion adsorption ability, demonstrated by the photodecomposition of Rhodamine B and the adsorption test of Cu2+, Cd2+, and Pb2+, respectively. A comparable photocatalytic activity with commercial P-25 and a selective complexation affinity for Cu2+ were observed in the synthesized hybrid materials, suggesting the promising catalysts and adsorbents for wastewater cleanup.