Self-assembly of FeIII-TAML-based microstructures for rapid degradation of bisphenols

Iron(III)-tetraamidomacrocyclic ligand (Fe-III-TAML) activators have drawn great attentions due to the high reactivity to degrade organic pollutants. However, previous studies showed that the reactivity and stability of Fe-III-TAML were both strongly pH-dependent, which dramatically decrease at lower pH levels. Herein, Fe-III-TAML/DODMA (dimethyldioctadecylammonium chloride) microspheres with diameters ranging from 100 to 2000 nm were synthesized via a surfactant-assisted self-assembly technique. The newly synthesized Fe-III-TAML/DODMA composite exhibits superior reactivity compared to free Fe-III-TAML as indicated by the degradation of bisphenols (i.e., bisphenol A and its analogues) over a wide pH range (i.e., pH 4.5-10.0). Based on the adsorption results and quantitative structure-activity relationship (QSAR) models, the enhanced reactivity of Fe-III-TAML/DODMA is mainly ascribed to the hydrophobic sorption of bisphenols. Moreover, the enhanced ionization of the axial water molecule associated with Fe-III-TAML could further enhance the reactivity of synthesized microcomposites, which was confirmed by the results of infrared and Raman spectra. Furthermore, Fe-III-TAML/DODMA shows distinct acid-resistance as explained by the protection of the hydrophobic alkyl chains of DODMA. This novel method would provide a simple and effective strategy to expand the application of Fe-III-TAML in a wide pH range and render Fe-III-TAML/DODMA microstructure as a potential catalyst for treatment of bisphenol compounds. (C) 2020 Elsevier Ltd. All rights reserved.