Rational construction of defects in a metal-organic framework for highly efficient adsorption and separation of dyes

In this work, UiO-66 with defects was successfully prepared by a synthesis strategy of using benzoic acid as a modulator and postsynthetic acid treatment. The defective frameworks can be confirmed by N-2 adsorption-desorption analysis and H-1 NMR. It is observed that this strategy can effectively enlarge the surface area and pore volume of stable UiO-66 through the removal of coordinated benzoate ligands. The resulting defective UiO-66 shows high BET surface area and total pore volume (1890 m(2)/g and 0.88 cm(3)/g), which are both larger than those of defect-free sample (1200 m(2)/g and 0.49 cm(3)/g) as well as all the reported UiO-66s with defects so far to the best of our knowledge. This MOF exhibits significantly improved capture ability (366 mg/g) toward Safranine T (ST) compared with the defect-free UiO-66 (39 mg/g) and most of reported adsorbents. Meanwhile, it also shows high selectivity for ST over Crystal Violet (CV) due to the size-exclusion effect constructed from the defects in the framework. The results show that this work provides a promising strategy to rationally design novel MOFs for separating large molecules. (C) 2016 Elsevier B.V. All rights reserved.