Adsorptive Removal of Catechol from Aqueous Solution with a Water-Stable and Hydroxyl-Functionalized Terbium–Organic Framework

Abstract

Nowadays, water pollution caused by diverse poisonous compounds, particularly hydroxy aromatic compounds and their derivatives, has become a prominent environmental issue because of the possible toxicity to human beings. This research adopted an adsorptive method to remove catechol using a water-stable hydroxyl-functionalized terbium–organic framework for the first time. The as-synthesized new metal–organic framework (Tb–MOF) shows favorable thermostability and water stability based on results of thermogravimetric analyses, water vapor sorption, and powder X-ray diffraction. Along the c axis, Tb–MOF has a three-dimensional framework with channels of 8.4 × 8.1 Å2 as well as high adsorption capacity with the maximal adsorption capacities of 260 mg/g for catechol than that of any reported adsorbent so far. Thermodynamics, adsorption kinetics, effects of pH, and effects of temperature were investigated in a batch reactor. The remarkably high adsorption capacity of Tb–MOF could be explained by the appropriate pore diameter of Tb–MOF in addition to the hydrogen bonding interplay of catechol molecules with Tb–MOF. In a breakthrough adsorption process of the Tb–MOF packed column, the adsorption breakthrough curve of a fixed bed for the catechol was found to favorably fit with the Thomas model. Because of its excellent catechol adsorption performance, the obtained Tb–MOF can be considered as a promising and suitable candidate as a high-performance catechol adsorber.