The key role of biochar in the rapid removal of decabromodiphenyl ether from aqueous solution by biochar-supported Ni/Fe bimetallic nanoparticles

Some problems exist in the current remediation of polybrominated diphenyl ethers (PBDEs) from aqueous solution by using iron-based nanoparticles. Our efforts have contributed to the synthesis of biochar-supported Ni/Fe bimetallic nanoparticle composites (BC@Ni/Fe). Under the optimum operating parameters of BC@Ni/Fe, the morphologic analysis revealed that biochar effectively solved the agglomeration of Ni/Fe nanoparticles and the removal efficiency of BDE209 obtained by BC@Ni/Fe (91.29%) was seven times higher than the sum of biochar (2.55%) and Ni/Fe (11.22%) in 10 min. The degradation products of BDE209 in the solution and absorbed on the BC@Ni/Fe were analyzed with gas chromatography-mass spectroscopy, which indicated that the degradation of BDE209 was mainly a process of stepwise debromination. Meanwhile, compared with Ni/Fe nanoparticles, the adsorption ability of the by-products of BDE209 by BC@Ni/Fe was greater, to a certain extent, which reduced the additional environmental burden. In addition, the concentration of nickle ion leaching from the Ni/Fe nanoparticles was 3.09 mg/L; conversely, the concentration of nickle leaching from BC@Ni/Fe was not detected. This excellent performance in our study indicates a possible means to enhance the reactivity and reduce the secondary risks of Ni/Fe nanoparticles.