Covalent Construction of Sustainable Hybrid UiO-66-NH2@Tb-CP Material for Selective Removal of Dyes and Detection of Metal Ions

The development of quick and effective strategies for the removal of organic dyes and the detection of metal ions in aqueous solutions remains a challenge for protecting the public health and environment. Multifunctional materials that combine both the dye-adsorption and pollutant-detection functions rarely have been explored. In this work, a 2D Tb(III) coordination polymer (Tb-CP) was directly assembled on the Zr(IV)-based UiO-66-NH2 matrix through covalent grafting, resulting in the new hybrid UiO-66-NH2@Tb-CP material. Benefiting from the porous structure of the parent UiO-66-NH2 matrix, the unique luminescent signal of Tb-CP, and the good structure and solvent stability, the fabricated UiO-66-NH2@Tb-CP material features a great potential for several cycles of absorption and release of organic dyes. Given the presence of Tb-CP, the resulting surface of UiO-66-NH2@Tb-CP has more positive charge exposing active sites and exhibits a particularly high and quick absorption (397.31 mg·g-1) of the Coomassie brilliant blue (R250) organic dye in aqueous solution, along with the fast desorption ability. More significantly, after absorption and desorption of different organic dyes, UiO-66-NH2@Tb-CP can be further used for detecting Cu2+ or Ce3+ ions via Tb(III) luminescence quenching. All processes from the absorption and desorption of organic dyes to the detection of metal ions are reversible, are efficient, and fit a requirement for new sustainable materials. The excellent performance of UiO-66-NH2@Tb-CP benefits from a high Brunauer-Emmett-Teller (BET) surface area of UiO-66-NH2 as well as a strong interaction between the two components of this hybrid material. "Tea bag" experiments further confirmed the efficiency and simplicity of the practical application of UiO-66-NH2@Tb-CP for the adsorption and desorption of the R250 dye, which can be monitored by the naked eye. The present work thus represents a unique example of the hybrid, covalently bound MOF-based material that can simultaneously be used as the sustainable and easily recoverable absorption material for toxic dyes and the luminescent probe for the quantitative recognition of metal cations in aqueous solutions. The present study provides new perspectives for the design of multifunctional MOF-based materials for applications in sustainable chemistry. © 2019 American Chemical Society.