Degradation of Chlorinated Organics By Temperature Responsive Pnipam-Co-PAA Functionalized MF Membranes with Reactive Nanoparticles

Degradation of Chlorinated Organics by Temperature Responsive PNIPAm-co-PAA Functionalized MF Membranes with Reactive Nanoparticles

Anthony Saad (speaker), Li Xiao, Minghui Gui, Dibakar Bhattacharyya

Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506

Abstract

This study is aimed at evaluating the effect of temperature on the degradation of chlorinated organics, specifically polychlorinated biphenyl. PVDF microfiltration membranes are functionalized with poly-N-isopropylacrylamide (PNIPAm), and its temperature responsive behavior is studied as it relates to water flux and partitioning of toxic pollutants. Effective pore size can be predicted based on the swelling extent of the temperature-responsive PNIPAm polymer around its LCST. PNIPAm is known to show a sharp transition to a hydrophobic state at its lower critical solution temperature (LCST) at around 32^oC, making PNIPAM attractive for industrial applications. Swelling ratios of PNIPAm polymeric networks have been reported in water, and are utilized to estimate changes in both flux and pore diameter.

The entrapment of reactive Fe/Pd nanoparticles in a poly-acrylic acid (PAA) polymer domain has been reported. Here, the NPs are entrapped in the temperature responsive PNIPAm-co-PAA polymer network for dechlorination and contaminant degradation of PCBs. This study aims to evaluate PCB degradation by reactive immobilized nanoparticles in a PNIPAm functionalized PVDF MF membrane. A model is formulated to account for diffusion through the membrane, as well as reactivity of the nanoparticles. Solute concentration is predicted as a function of length through the membrane, and also as a function of time. Increasing the surrounding temperature affects inter-particle spacing and solute adsorption because of the changing PNIPAm conformation, as well as the intrinsic rate constant for the reaction. These effects are predicted, and verified by experimental degradation results. This research is supported by the NIEHS-SRP grant P42ES007380, and by the NSF KY EPSCOR program. Full-scale PVDF membranes were developed through collaborative work with Nanostone-Sepro (Oceanside, CA, USA).