Construction of defective zirconium-based metal–organic frameworks for enhanced removal of toxic selenite: performance and mechanism studies

Abstract

The development of effective adsorbents for the adsorption and removal of toxic selenite (SeO32−) from wastewater is urgently required but challenging. Herein, formic acid (FA), a monocarboxylic acid, was used as a template to construct serial defective Zr-Fumarate (Fum) -FA based on a green and facile preparation method. Physicochemical characterization shows that the defect degree of Zr-Fum-FA can be flexibly controlled by regulating the amount of FA to be added. Owing to rich defect units, the diffusion and mass transfer of guest SeO32− into the channel can be boosted. Particularly, Zr-Fum-FA-6 with the most defects exhibits superior adsorption capacity (519.6 mg g−1) and rapid adsorption equilibrium (∼200 min). The adsorption isotherms and kinetics can be well described by the Langmuir and pseudo-second-order kinetic models. Moreover, this adsorbent possesses excellent resistance towards co-existing ions, high chemical stability and good applicability in a broad pH range of 3–10. Thus, our study provides a promising adsorbent for SeO32−, and more importantly, it proposes a strategy for rationally tailoring the adsorption behavior of adsorbents via defect construction.