Carbon nanotubes mediating nano α-FeOOH reduction by Shewanella putrefaciens CN32 to enhance tetrabromobisphenol A removal

Carbon nanotubes (CNTs) mediation of the reduction of nano goethite (alpha-FeOOH) by Shewanella putrefaciens CN32 to improve the removal efficiency of tetrabromobisphenol A (TBBPA) was investigated in this study. The results showed that CNTs effectively promoted the biological reduction of alpha-FeOOH by strengthening the electron transfer process between Shewanella putrefaciens CN32 and alpha-FeOOH. After alpha-FeOOH was reduced to Fe(II), the adsorbed Fe (II) accounted for approximately 69.07% of the total Fe(II). And the secondary mineral vivianite was formed during the reduction of alpha-FeOOH, which was determined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The vivianite (Fe-3(II)(PO4)(2) center dot 8H(2)O) was formed by the reaction of PO4(3)(-) and Fe(II). The degradation effect of TBBPA was the best at pH 8. CNT-alpha-FeOOH reduced the toxicity of TBBPA to CN32 and had good stability and reusability. The byproduct bisphenol A was detected which indicated that the degradation pathway of TBBPA involved reductive debromination. Electrochemical experiments and EPR analysis showed that the electron transfer capacities (ETC) of CNTs was an important factor in the removal of TBBPA, and it may greatly depend on semiquinone radicals (C=O). This study provided a new method and theoretical support for the removal of TBBPA in the environment. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the mediation of carbon nanotubes in the reduction of nano goethite by Shewanella putrefaciens CN32 to improve the removal efficiency of tetrabromobisphenol A. The results showed that the electron transfer process was enhanced by CNTs and secondary mineral vivianite was formed during the reduction of alpha-FeOOH. The degradation of TBBPA was most effective at pH 8, and the byproduct bisphenol A was detected, indicating a reductive debromination pathway. Electrochemical experiments revealed the importance of electron transfer capacities in the removal of TBBPA.