Rapid removal of tetrabromobisphenol A by alpha-Fe2O3-x@Graphene@Montmorillonite catalyst with oxygen vacancies through peroxymonosulfate activation: Role of halogen and alpha-hydroxyalkyl radicals

We employed hydrolyzed iron-pillared montmorillonite/tetracycline complex (FeOOH-Mt-TC) as precursor to prepare iron oxide@Graphene@Montmorillonite composite (alpha-Fe2O3-x@Graphene@Mt) through pyrolysis strategy under nitrogen atmosphere. During the pyrolysis process, the involvement of hydrolyzed iron (FeOOH) and TC made the alpha-Fe2O3-x@Graphene@Mt composite have superior conductivity, higher percent of structural Fe(II) and abundant oxygen vacancies, resulting in highly-efficient degradation of tetrabromobisphenol A (TBBPA) in the presence of PMS. Meanwhile, O-2(center dot-) played the leading role in the oxidation process when compared with (OH)-O-center dot, SO4 center dot- and O-1(2). In addition, the released Br- from TBBPA and the addition of alcohol led to the formation of reactive halogen and alpha-hydroxyalkyl radicals, which contributed to the rapid removal of TBBPA. This study not only provided a novel strategy to prepare excellent iron-based catalysts for PMS activation, but also evaluated the application of reactive halogen and alpha-hydroxyalkyl radicals in the treatment of halogenated organic pollutants.