Nanoparticles embedded membrane reactor for the reductive degradation of chlorinated organics: TCE and FCB studies

The use of chitosan as the polymeric material for the synthesis of novel membrane reactor with bimetallic nanoparticles (Ni/Fe, Pd/Fe) is described. The objective of this study is to test the feasibility of the Ni/Fe and Pd/Fe nanoparticles embedded in the chitosan as the mixed matrix membrane reactor in the degradation of chlorinated organics such as trichloroethylene and polychlorinated biphenyl (PCB). The membrane is characterized by conventional methods such as XRD, TGA, and FTIR. Formation of nanosized particles is confirmed by SEM and X-ray energy dispersive analyses. Nanoparticles distribution is found to be uniform on the surface as well as in the porous membrane matrix. HRTEM micrograph showed that the nanoparticles detected by SEM are actually nanoclusters consist of 3 nm to 5 nm particles. Preliminary kinetic studies of chlorinated organics showed that complete degradation is achieved at room temperature using mg quantity of the embedded bimetallic Ni/Fe and Pd/Fe nanoparticles in the chitosan membranes. The catalytic effect of the second dopant metal in the mixed matrix membrane reactor is shown by the significant enhancement in the reaction rate as well as the end products formation of the bimetallic Ni/Fe as compared to Fe nanoparticles. In addition, the leaching of metals is found to be negligible at the end of the degradation reaction. This is due to the chelating effect of the amine as well as the hydroxyl functional groups that exist in the chitosan backbones. Our research showed that the use of mixed matrix membrane consists of nanostructured metals (Ni/Fe, Pd/Fe) is expected to have significant positive impact on pollution remediation through compact and flexible dechlorination technology development with high reaction rates at room temperature, and significant reduction of metals usage as well as improved recovery of precious metals.