(743c) Functionalized Poly(methacrylic acid) Membranes with Bimetallic Nanoparticles: From Bench Scale to Water Remediation Applications

The detoxification of toxic chlorinated organics (chlorophenol, trichloroethylene) in groundwater has been widely investigated using bimetallic (Fe/Pd) nanoparticle methods [1,2]. With the integration of catalytic particles and functionalized commercial membranes, this membrane platform shows improved scalability and ease of recycle. This integration was achieved in both commercial flat-sheet membranes and spiral membrane modules. The Fe/Pd nanoparticle was formed inside the pores of membrane through in situ reduction after chelating by introduced carboxylate groups (methacrylic acid (MAA) was polymerized inside the membrane). The functionalized MAA could prevent nanoparticle aggregation and metal ion loss (recapture after dechlorination treatment). The metal nanoparticle-based membrane system showed great performance on the treatment of lab synergic polychlorinated biphenyls and field water samples (from a Superfund site, which includes trichloroethylene, tetrachloroethylene and carbon tetrachloride). At 2 seconds residence time, 95% of chlorinated organic species (ppm level) in the field samples were dechlorinated in the convective flow mode. The pilot studies with functionalized commercial spiral membrane modules are in progress.

Advanced characterization methods, such as FIB, TEM, XPS were applied to understand the correlation between nanoparticle properties and depth inside membrane pores, leading to the optimization of membrane design and treatment performance. The depth profile of functionalized membrane indicated that particle size was uniform inside membrane pores (particle size: 24±6 nm) but slightly smaller than those nanoparticles located on the surface (39±9 nm). Besides, the distribution of particles inside the membrane as well as the composition of single palladized-iron nanoparticles were analyzed by using EDS and EELS. Furthermore, the effects of pH, temperature as well as water hardness on the dechlorination treatment were studied. These investigations illustrated the advantages of the Fe/Pd particle based membrane system method, compared to the conventional applications of the metal nanoparticles.

In XRD analysis, the Fe/Pd particle samples (which were deliberately oxidized and then reduced) exhibited the same crystalline patterns as the original samples. The membrane maintained reactivity after four degradation cycles with regeneration between each cycle. The increase of surface particle size of 22% resulted in a decrease of 9.7% PCB conversion for the 4 hr reaction time [3].

This research is supported by the NIEHS-SRP grant P42ES007380. Partial support is also provided by NSF KY EPSCoR grant (Grant no: 1355438).