Bisphenol A degradation enhanced by air bubbles via advanced oxidation using in situ generated ferrous ions from nano zero-valent iron/palygorskite composite materials

• nZVI/palygorskite composite materials are synthesized via two routes.
• The obtained composites are characterized by XRD, SEM–EDS, TEM and XPS.
• The removal efficiencies for bishphenol A in water are studied.
• The removal efficiencies can be increased significantly with the aid of air bubbles.
• The prepared composite shows potential prospects in environmental remediation.

Novel nano zero-valent iron/palygorskite composite materials prepared by evaporative and centrifuge methods are tested for the degradation of bisphenol A in an aqueous medium. A systematic study is presented which showed that nano zero-valent iron material has little effect on bisphenol A degradation. When hydrogen peroxide was added to initiate the reaction, some percentage of bisphenol A removal (∼20%) was achieved; however, with the aid of air bubbles, the percentage removal can be significantly increased to ∼99%. Compared with pristine nano zero-valent iron and commercial iron powder, nano zero-valent iron/palygorskite composite materials have much higher reactivity towards bisphenol A and these materials are superior as they have little impact on the solution pH. However, for pristine nano zero-valent iron, it is difficult to maintain the reaction system at a favourable low pH which is a key factor in maintaining high bisphenol A removal. All materials were characterized by X-ray diffraction, scanning electron microscopy, elemental analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. The optimum conditions were obtained based on a series of batch experiments. This study has extended the application of nano zero-valent iron/palygorskite composites as effective materials for the removal of phenolic compounds from the environment.

Nano zero-valent iron/palygorskite composite materials were synthesized and used for bisphenol A degradation via radical reaction. Compared with pristine nano zero-valent iron and commercial iron powder, the composite materials showed superior efficiency on the contaminant removal attributed to the highly dispersed spherical nano iron particles on the surface. It was observed that the air bubbles can increase the removal percentage significantly.Figure optionsDownload as PowerPoint slide