(13c) Membrane Immobilized Nanostructured Metals for Detoxification of Chloro-Organics

Nanostructured metals have become an important class of materials in the field of catalysis, optical, electronic, magnetic and biological devices due to the unique physical and chemical properties. Extensive studies have been reported on the degradation of toxic chlorinated organics (such as, TCE, PCB) with non-immobilized Fe based bulk/nano particles. Immobilization of metal nanoparticles (Fe/Pd, Fe/Ni) in polymer membrane (such as, cellulose acetate, PVDF, polysulfone, chitosan, etc,) media is important from the point of view of reactivity, organic partitioning, preventing loss of nanoparticles, and reduction of surface passivation. Another major advantage of having a polymer domain is that nanoparticles (without causing agglomeration) can be directly synthesized in the matrix. We developed a novel in-situ synthesis method of bimetallic nanoparticles (20-50 nm) embedded in polyacrylic acid (PAA) functionalized microfiltration type membranes by chemical reduction of metal ions bound to the carboxylic acid groups. Polymer immobilization eliminates worker exposure issues relating to nanoparticles. We demonstrated complete (with product and intermediates analysis) dechlorination of trichloroethylene (TCE) and selected PCBs by nanosized metals. The 2nd dopant metal (such as, Ni, Pd) plays a very important role in terms of catalytic property (hydrodechlorination) and the significant minimization of intermediates formation. 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. The presentation will include NP synthesis by green chemistry, toxic organic degradation rates, role of hydrogen from the iron corrosion reaction, the effect of 2nd dopant metal (Pd), and toxicity reduction data of PCB conversion to biphenyl. This research has been supported by the NIEHS ? SBRP program and by DOE-KRCEE.