Functionalized polyvinylidene fluoride membrane platforms, due to their excellent chemical resistance and mechanical properties, were developed for environmentally benign in-situ nanostructured Fe/Pd synthesis and remediation of chlorinated contaminates (PCB and TCE). In this dechlorination process, Fe is used as an electron and hydrogen source and Pd as a catalyst. Hydrogen, yielding from Fe0 corrosion in water, is activated by Pd to convert to hydrogen radical. Hydrogen radicals serve as effective reductants for PCB degradation. To increase the accuracy of kinetic analysis and simulation of PCB dechlorination, the correlation between nanoparticle properties and depth inside membrane pores was studied by using focused ion beam. 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. 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.

Optimization of Fe/Pd nanoparticles immobilized membrane systems for PCB degradation

254th National Meeting (2017)

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