Highly Efficient Removal of Cr(VI) on a Stable Metal-Organic Framework Based on Enhanced H-bond Interaction

Chromium(VI) is known for its severe threaten to human and environment. Herein, a valid strategy has been developed to effectively remove this pollutant. Based on the short organic linker of fumaric acid, MOF-801 (or Zr-fum) is the smallest Zr-MOF with fcu topology up to date. Accordingly, this Zr-MOF owns much higher density of μ-OH sites than other fcu-Zr-MOFs. Based on the H-bond interaction between Cr(VI) and these μ-OH sites, MOF-801 shows a high maximum adsorption capacity of 156.2 mg g-1, superior to other two fcu-Zr-MOFs and most of reported adsorbents. Besides, the adsorption equilibrium can be achieved at ~60 min and most of co-existing salts have only slight influences on Cr(VI) adsorption in MOF-801; more importantly, MOF-801 can be well regenerated with the eluent of methanol-acetic acid. Adsorption mechanism as well as the important role of μ-OH was reasonably explained through FT-IR spectra, XPS pattern, theoretical calculation and zeta potential measurement.