Polymeric System for Photochemical Generation of H2O2 and Initiator for Photoreduction of Hexavalent Chromium

Abstract

Stimuli responsive polymers (SRPs) have become a technological advancement in areas of materials, pharmaceuticals, and biomedical applications because the polymers can respond to small changes in the environment which can be physical, chemical, or biochemical stimuli. By incorporating SRPs in fabrics, functions such as wound monitoring, skin-care capabilities, moisture/temperature management, and aesthetic appeal, to name a few, can be achieved. Utilizing light in the field of stimuli-responsive polymers has attracted great attention because of its renewable source of energy and its ability to be localized in time and space. The focus of this work is to show the chemistry of a polymeric system which can be used as a foundation to creating a potentially “smart” polymeric material. Presented in the dissertation is the potential use of a photochemical polymeric system that can utilize its redox reactivity as a means of providing personal and environmental protection. Macromolecular systems containing reactive species are envisioned to function as protective barriers, such as reactive clothing, which chemically inactivate toxins and pathogens. Protective barriers based on polymeric sensitizers that generate reactive species photochemically are an attractive approach. An advantage of such barriers is their ability to regenerate reactive species by exposure to light. Presented in this dissertation are data obtained from photolysis experiments of crosslinked films from SPEEK/PVA blends. As in previous investigations dealing with photoreactions initiated in solid matrices, SPEEK/PVA films were immersed into air-saturated aqueous solutions during irradiations, because such an arrangement enabled the use of conventional analytical methods for [H2O2] quantification. Interestingly, the efficiency of peroxide generation was found to be significantly higher than the quantum yield determined for solutions of the polymer blends. Decontamination is not only a concern centered on the degradation of toxic chemical and biological agents on surfaces of materials and materials used for personal protection, but also for disinfection of water. The polymeric system explored in this dissertation has great potential to treat waste waters contaminated with hexavalent chromium as a filtering membrane. The reduction processes as well as the factors influencing the rates of reaction such as light intensity, buffer concentrations, effects of pH, and effects of initial chromium concentration have been studied in order to get a basic insight into the reduction process of the polymer-assisted photoreduction of hexavalent chromium.