(41f) Reactive Nanoparticles Immobilized In Hydrogel for Toxic Organics Degradation

Nanoscale metallic particles have important applications in the environmentally important catalytic reactions due to the novel physical and chemical properties over bulk particles. Functionalized membrane supported metallic nanoparticles can be used to conduct reductive detoxification of chlorinated organics. In this research, a novel strategy was employed for stabilizing metalic nanoparticles with temperature responsive hydrogel (poly - N-isopropylacrylamide) as stabilizer. Hydrogel/Membrane immobilized nanoparticles possess many advantages: prevention of aggregation, tunable nanoparticle size and morphology, and potentially adjustable reactivity by the variance of hydrophobicity and hydrophilicity with the environmental change.

 In this work, poly (N-isopropylacrylamide-co-acrylic acid) [p(NIPAAm-AA) immobilized metallic nanoparticles were synthesized with uniform size (around 30nm~50nm) and distribution immobilized in polymer domain.  These iron nanoparticles containing hydrogel-composites were utilized as a reaction media for the reduction reactions of chlorinated organics. Also, this polymer network has tunable properties and it was found that reactivity toward TCE dechlorination with Fe/Pd (2 wt% Pd) increased three fold with a temperature change of only 4 ℃. On the other hand, experiments without any hydrogel showed an increase of only two fold, showing the importance of hydrogel tunable properties. Hydrogel supported nanoparticles can be regenerated and reused only with 30% reduction in the initial reduction rate. The dechlorination of dichlorobiphenyl was also conducted with the system of bimetallic nanoparticles Fe/Pd (4.6 wt% Pd) nanoparticles immobilized in hydrogel. The batch reaction results showed the formation of biphenyl and complete dechlorination (as measured by chloride analysis) at 25 ℃. Support of this research has been provided by NSF-IGERT and NIEHS-SRP.