Superfund Research Program
Chloro-Organic Degradation by Polymer Membrane Immobilized Iron-Based Particle Systems
Project Leader: Dibakar Bhattacharyya
Grant Number: P42ES007380
Funding Period: 2000-2019
This work is focused on advancing water remediation by nanostructured membrane-based technologies for the degradation of chlorinated organic compounds to non-toxic products. A variety of membrane platforms were explored: full-scale flat-sheet polyvinylidene fluoride (PVDF) membranes, metallic thin films, and graphene-based membranes. The PVDF membranes were functionalized with the responsive cross-linked polymers (pH responsive and temperature responsive). Reactive iron/palladium nanoparticles were then synthesized in situ inside the polymers. Polymerization parameters of monomer and cross-linker concentrations were optimized for catalytic metal loading capacity and remediation performance. The loaded nanoparticles were characterized using novel focused ion beam technology (FIB, purchased through NSF funding) at various depths within membrane pores, enabling modeling development and optimization of membrane functionalization to maximize particle reactivity. TCE and PCBs were effectively degraded using various platforms to non-toxic products through reductive and oxidative pathways. Within the chloro-organics, PCB 126 is considered one of the more difficult to degrade pollutants because of the multiple chlorines per molecule. This molecule was degraded in their group using the membrane technology involving multiple membrane treatment cycles. This membrane technology provided optimal performance even after four regeneration and reuse cycles for PCB dechlorination. Another advancement was in the area of creating thin nanonporous bimetallic films directly on commercial membrane surfaces. These films demonstrated over 99% dechlorination of chloro-biphenyl. Also, the nanocomposite system of graphene oxide membrane and with iron was investigated for the more efficient oxidative treatment of chlorinated organics. The researchers’ membrane support technology from the NIEHS work has found other applications. First, a collaboration with Northeastern University Superfund Research Program in the TCE degradation through electrocatalysis using Pd-only functionalized membranes. Second, their group is assessing chlorinated organics degradation and metal capture of real water mixtures obtained from an environmental consultancy firm (Superfund site) and from an oil company. Finally, a collaboration with the Chemistry Department at the University of Kentucky in the selective separation of model organics from salts using layer-by-layer (LbL) technique and "porin" channels on top of their functionalized membranes.