Efficient activation of persulfate by Fe₃O₄@β-cyclodextrin nanocomposite for removal of bisphenol A

Experimental studies were conducted to investigate the degradation of bisphenol A (BPA) by using persulfate (PS) as the oxidant and Fe₃O₄@β-cyclodextrin (β-CD) nanocomposite as a heterogeneous activator. The catalytic activity was evaluated in consideration of the effect of various parameters, such as pH value, PS concentration and Fe₃O₄@β-CD load. The results showed that 100% removal of BPA was gained at pH 3.0 with 5 mM PS, 1.0 g L^-1 Fe₃O₄@β-CD, and 0.1 mM BPA in 120 min. Further, the catalytic activity of Fe₃O₄@β-CD nanocomposite was observed as much higher when compared with Fe₃O₄ nanoparticles alone. The sulfate and hydroxyl radicals referred to in the Fe₃O₄@β-CD/PS system were determined as the reactive species responsible for the degradation of BPA by radical quenching and electron spin resonance (ESR) tests. In addition, the catalyst also possessed with accepted reusability and stability. On the basis of the results of the effect of chloride ions (Cl^-), β-CD was found to play a crucial role in reducing interference from Cl^- ions, and lead to achieve higher removal efficiency for BPA in Fe₃O₄@β-CD/PS system. A possible mechanistic process of BPA degradation was proposed according to the identified intermediates by gas chromatography-mass spectroscopy (GC-MS).