Hierarchically porous covalent organic framework for adsorption and removal of triphenylmethane dyes

Abstract

Triphenylmethane (TPM) dyes as one of common organic pollutants have been severely criticized while it comes to their negative effects on the environment and human beings. In this study, using 1,3,5-triformylbenzene (Tb) and benzidine (Bd) as building blocks, we fabricated a hierarchically porous covalent organic framework foam (TbBd-foam) via a simple yet accomplished gas-foaming technique to adsorb and remove two typical TPM dyes malachite green (MG) and crystal violet (CV) from aqueous solution. Attributed to the use of baking soda, CO2 effervesced continuously during the crystallization of TbBd-foam, and thereby creating disordered porous system which can quicken the diffusion of MG and CV through the pore network in TbBd-foam. Benefit from this merit, the adsorption equilibrium of MG and CV can reach only with 30 min, and the maximum adsorption capacity of TbBd-foam for MG and CV was calculated to be 172.4 mg g−1 and 149.3 mg g−1, respectively. More fascinatingly, TbBd-foam can be facilely recycled upon the treatment with ethanol solution containing HCl (0.1%). Taken together, TbBd-foam might be a potential adsorbent for high-performance contaminated water remediation.