Adsorptive Removal of Catechol from Aqueous Solution\nwith a Water-Stable and Hydroxyl-Functionalized Terbium–Organic\nFramework

Abstract

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