Kinetics and mechanisms of debromination of tetrabromobisphenol A by Cu coated nano zerovalent iron

Abstract

Brominated flame retardants are of concern to our environment because of its endocrine disruptive, immune toxicant characteristics, and toxic brominated byproducts. As a potential remediation technology, debromination of tetrabromobisphenol A (TBBPA) from both aqua and soil by Cu coated nano zero-valent iron particles (Cu-nZVI) was investigated. Because of its catalytic reductive properties, Cu-nZVI has a potential for removing TBBPA. Batch experiments show that Cu-nZVI effectively debrominated TBBPA into tri-, di-, mono-bromobisphenol A, and bisphenol A (BPA) with a low suspension density (0.5 g L−1). As indicated by the low apparent activation energy (69.66 kJ mol−1), the optimal reaction condition was the Cu loading of 0.5 wt%, 27 °C and pH 5.0. Tetrabromobisphenol A (10 mg L−1) was transformed into several reaction products within 120 min, and BPA was detected as a major reaction product after 240 min. The reaction rate constant (kobs) was proportionally correlated to solid-solution ratio and temperature. The concentration of metals during the debromination was too low (less than 0.13 mg L−1) to induce an adverse effect on the ecosystem. During the redox reaction, a new mineral, magnetite formed on particles’ surface accompanied by the oxidation of Fe0 and the elevation of pH. This study suggests that Cu-nZVI has the potential to be explored for the rapid and complete debromination of brominated flame retardants in both aquatic and edaphic environments.