Fe/Pd nanoparticle immobilization in microfiltration membrane pores: Synthesis, characterization, and application in the dechlorination of polychlorinated biphenyls

Nanosized Fe/Pd bimetallic particles are an important category of materials in the area of reductive degradation of chlorinated organics. In this work, we prepared Fe/Pd nanoparticles in three steps: polymerization of acrylic acid (AA) in poly(vinylidene fluoride) (PVDF) microfiltration membrane pores, subsequent ion exchange of Fe²⁺, and chemical reduction (by borohydride) of ferrous ions bound to the carboxylic acid groups. Fe/Pd bimetallic nanoparticles were formed by the partial reduction of Pd²⁺ with Fe⁰ nanoparticles. The functionalized membrane and the nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The membrane-supported nanoparticles exhibited high reactivity in the dechlorination of 2,2′-dichlorobiphenyl (DiCB) used as a model compound. The dechlorination mechanism and the role of water were probed by conducting the reaction in pure ethanol solution. Bulk Fe/Pd particles were also prepared to investigate the effect of particle size on the catalytic activity. The effect of Pd content on the catalytic activity was studied to understand and quantify the role of Pd in the bimetallic nanoparticle system. The high catalytic activity of Pd was confirmed by the low activation energy compared to those other catalytic systems.