Au/Boron organic frameworks for efficient removal and degradation of azo dye pollutants

Abstract

The discharges from urban industries and domestic sewages have caused severe environmental pollution problems. Specifically, dyes are among the pollution sources that are relatively difficult to treat. In this study, Au/CB6-BOFs (BOFs namely closo-dodecaborate-based supramolecular organic frameworks) were successfully synthesized using a simple method. The sample was used as adsorbent and degradation agents on Congo red (CR) and methyl orange (MO). The adsorption effect of Au/CB6-BOFs on CR is excellent with the adsorption capacity reaching as high as 2178.36 mg g−1. Experiments, including adsorption kinetics, isothermal adsorption, and adsorption thermodynamics, were conducted on Au/CB6-BOFs to verify its performance, which confirmed that the adsorption type is monolayer chemical adsorption and that the reaction proceeds spontaneously. Au/CB6-BOFs can lead to catalytic degradation of dye molecules in aqueous solution with the addition of sodium borohydride. The adsorption/degradation ability of Au/CB6-BOFs can be maintained for at least five times without significant attenuating. FT-IR spectroscope and XRD were used to investigate Au/CB6-BOFs changes before and after experiments, there has been no obvious change observed in the FT-IR and XRD results. The catalytic mechanism was also proposed based on the degradation performance. In previous reports, it is might impossible to see similar nanomaterials that combine dye adsorption and dye degradation. If our material does either of them alone, it has a good effect. Considering that Au/CB6-BOFs have two functions at the same time, the initial concentrations of dyes that we set are relatively high, which is beyond the relevant literature reports. Therefore, it has certain reference value and impelling function to shorten the subsequent industrial treatment process of dye wastewater. This study provides a simple method to design and synthesis adsorption/degradation agents, which may open a new path for dye wastewater treatment.