Design and synthesis of architectured materials for the removal of selected chemical contaminants in water

Abstract

Water contaminants affect not only aquatic ecosystems but also human health. The demand for an efficient and sustainable technology to purify and renovate contaminated water is ever-growing. The first part of this dissertation focuses on the electrochemical reduction of nitrate using bimetallic electrodes. The goal is to convert nitrate into harmless nitrogen gas. We first demonstrated that the incorporation of second metal into the electrodes can influence the surface morphology as well as reaction mechanism, leading to the improved nitrate conversion and the generation of N2. The performance of bimetallic electrodes on nitrate reduction was further developed by modifying electrode preparation procedures including electrodeposition steps, bimetal ordering, deposition time, and bimetal composition. The optimal electrode in this work can achieve nearly 100% nitrate removal and 81% N2 yield. The second part of this dissertation proposes a new design of composite adsorbents for fluoride removal. Block copolymers were applied as a soft template to generate unique macroporous adsorbents, and the fluoride adsorption capacity of resulting materials was found to be one order of magnitude higher than similar adsorbents reported in the literatures. In the last section, photoelectrochemical (PEC) methods was applied for the removal of organic contaminants in water. The degradation of methyl orange (MO) was achieved simply by the action of light. Additionally, self-biasing PEC system was assembled and successfully reduced nitrate and degraded MO simultaneously. Overall, the approaches presented in this dissertation provide the opportunity to design cost-effective and highly-efficient materials for water treatment applications.