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

Abstract We employed hydrolyzed iron-pillared montmorillonite/tetracycline complex (FeOOH- Mt-TC) as precursor to prepare iron oxide@Graphene@ Montmorillonitecomposite (α-Fe2O3-x@Graphene@Mt) through pyrolysis strategy under nitrogen atmosphere. During the pyrolysis process, the involvement of hydrolyzed iron (FeOOH) and TC made the α-Fe2O3-x@Graphene@Mt composite have superior conductivity, higher percent of structural Fe(II) and abundant oxygen vacancies, resulting in highly-efficient degradation of tetrabromobisphenolA (TBBPA) in the presence of PMS. Meanwhile, O2•− played the leading role in the oxidation process when compared with •OH, SO4•− and 1O2. In addition, the released Br− from TBBPA and the addition of alcohol led to the formation of reactive halogenand α-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 halogenand α-hydroxyalkyl radicals in the treatment of halogenatedorganic pollutants.