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

Abstract

Chromium(VI) is known for its severe threat to humans and the 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 possesses 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 the 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. The adsorption mechanism as well as the important role of μ-OH was reasonably explained through Fourier transform infrared spectra, XPS pattern, theoretical calculation, and zeta potential measurement.