Enhanced debromination of tetrabromobisphoenol a by zero-valent copper-nanoparticle-modified green rusts

Abstract

Green rusts (GRs) interlayered with Cl⁻, SO₄²⁻, and CO₃²⁻ were used to reduce tetrabromobisphenol A (TBBPA), which is the most widely used brominated flame retardant. The modification of GRs by copper nanoparticles (Cu NPs) greatly enhanced the reductive reactivity of GR. GR(Cl)–Cu NPs with a Cu NPs content of 0.5% had the highest reactivity toward TBBPA reduction. High pH did not favor TBBPA reduction by both GR(Cl) and GR(Cl)–Cu NPs. The presence of SO₄²⁻ and CO₃²⁻ inhibited TBBPA reduction by GR(Cl) and GR(Cl)–Cu NPs, whereas the inhibition effect of PO₄³⁻ and humic acid was much greater than those for SO₄²⁻ and CO₃²⁻. The TBBPA reduction by GR(Cl)–Cu NPs could be explained by a galvanic cell model, where electrons are transferred from GR(Cl) to Cu NPs, where TBBPA reduction occurs. Our findings demonstrate that nature-occurring Fe-bearing minerals may play an important role in the reductive transformation of TBBPA besides the biotransformation and that GR(Cl)–Cu NPs can be used for the efficient removal of reducible halogenated pollutants.