(173f) Iron/Palladium Nanoparticle Functionalized Membrane for Chlorinated Contaminates Treatment

Functionalized polyvinylidene fluoride (PVDF) membrane platforms were developed for environmentally benign in-situ nanostructured Fe/Pd synthesis and remediation of chlorinated contaminates (PCB and TCE). To prevent leaching and aggregation, nanoparticle catalysts were integrated into membrane domains functionalized with poly (acrylic acid). Furthermore, nanoparticles of 16-19 nm were observed inside the membrane pores. The quantification of nanoparticles properties (size, distribution and composition) versus depth underneath the membrane surface was also investigated by cross-sectioning the membrane samples with focused ion beam (FIB). The Fe/Pd nanoparticles immobilized membrane showed excellent performance in the degradation of chlorinated organics and also the repeated degradation experiments were conducted to demonstrate the reusability of Fe/Pd immobilized membranes.

To increase the accuracy of kinetic analysis and further simulation of PCB dechlorination, the correlation between nanoparticle properties and depth inside membrane pores was studied by using FIB. Particle size was uniform inside membrane pores at different depths (particle size: 16.7±0.7 nm) but slightly smaller than those nanoparticles located on the surface (19.4±3.2 nm). Furthermore, the fairly similar surface coverage values (0.169±0.011) demonstrated the evenly distributed nanoparticles inside the membrane pores. Besides, the element composition of particles as well as the functionalized membrane domain were analyzed in line-scan mode by using energy dispersive spectroscopy (EDS).

Over 96% degradation of 3,3',4,4',5-pentachlorobiphenyl was achieved at a residence time of 14.7 seconds in the membrane pores. The ksa was calculated (using LFR model) to be 0.171 L/(m²h) in convective flow mode, which is 2.5 times the rate obtained in batch mode. The effects of temperature and pH values were also investigated.

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 was tested for 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. [1]

This research is supported by the NIEHS-SRP grant P42ES007380.

Reference:

[1] Wan, Hongyi, L. Ormsbee, and D. Bhattacharyya. "Pore functionalized PVDF membranes with in-situ synthesized metal nanoparticles: Material characterization, and toxic organic degradation." Journal of Membrane Science 530 (2017): 147-157.