(50c) Nanoparticle-Based Functionalized Membrane Reactor for Chloro-Organic Detoxification at Room Temperature: An Overview (Invited Paper)

The study of reductive dechlorination technology involved the synthesis of hybrid membrane materials containing bimetallic (Fe/Ni, Fe/Pd) iron-based nanoparticles using either functionalization and ion-exchange principles or phase-inversion membrane processing. We synthesized and immobilized bimetallic nanoparticles with controlled diameters < 30 nm using membrane-based supports (such as PVDF and Chitosan). In addition to the rapid degradation (by Fe/Ni) of TCE (trichloroethylene) to ethane, we were also able to achieve complete dechlorination of selected chloro-biphenyls (PCBs) using milligram quantities immobilized Fe/Pd nanoparticles in membrane domain. For the PVDF membrane supports we synthesized core/shell Fe/Pd nanoparticles in polyvinylidene fluoride (PVDF) microfiltration membranes functionalized with poly(acrylic acid) (PAA). PAA functionalization was achieved by in situ free radical polymerization of acrylic acid in microfiltration membrane pores. Target ferrous ions were then introduced into the membranes by the ion exchange process. Subsequent reduction resulted in the in situ formation of 20-40 nm Fe nanoparticles. Bimetallic nanoparticles can be formed by post-deposition of Pd. The membranes and Fe/Pd nanoparticles were characterized by thermogravimetric analyzer (TGA), FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). 2,2′-Dichlorobiphenyl (PCB4) and 3,3′,4,4′-tertrachlorobiphenyl (PCB77) were chosen as the model compounds to investigate the catalytic properties of bimetallic nanoparticles, the reaction mechanism, and the intrinsic kinetics. A two-dimensional steady-state model was also developed to correlate and simulate mass transfer and reaction in the membrane pores under pressure-driven convective flow conditions. This research was supported by the NIEHS-SBRP Program.