Development of a Scalable, Low-cost, Ultrananocrystalline Diamond Electrochemical Process for the Destruction of Contaminants of Emerging Concern (CECs)

This Small Business Innovation Research (SBIR) Phase II project will employ the large scale; highly reliable boron-doped ultrananocrystalline diamond (BD-UNCD®) electrodes developed during Phase I project to build and test Electrochemical Anodic Oxidation process (EAOP) cells and systems that can destroy Contaminants of Emerging Concern more economically and effectively than competing AOPs. BD-UNCD cells are likely to demonstrate higher rates of organiccontaminant destruction at lower costs and with greater energy efficiency than competing electrodes due to higher current densities allowing smaller electrode sizes and higher rates of hydroxyl-radical generation. The known difficulties with existing EAOP electrodes (e.g. DSA) such as an inadequate rate of destruction of refractory molecules, unreliable operation below 10°C, generation of large quantities of 02 and H2, which worsen current efficiency and present safety concerns, electrode fouling, limited electrode lifetime and an inability to be reverse-polarized are addressed using BD-UNCD electrodes as was demonstrated in the Phase I. The powerful combination of hydroxyl radicals, H202 and other strong oxidants fanned at the BD-UNCD anode is capable of oxidative destruction of even refractory organics such as trichloroethylene. BD-UNCD EAOP typically reduces the cost by at least an order of magnitude compared to competing AOPs. The non-chemical water treatment market in the USA for 2009 was greater than $4 billion. Much of this market is addressed by ozonolysis, which is at least an order of magnitude more expensive and less effective for refractory organics. The potential market for a lower-cost water purification technology capable of destruction of refractory organics is therefore expected to exceed the current ozonolysis market Current methods are problematic for many reasons including, poor mineralization; formation of persistent by-products; usually limited to lower concentration wastes; they also require the addition, and subsequent emoval, of chemicals such as H202 or Ozone; require pH adjustments, safety hazards associated with transporting chemical and energy inefficiency with high carbon footprints. Overcoming these technical barriers will require advances in the Synthesis and large-scale manufacturing of diamond thin films (completed in phase II) and their application and tuning to the target wastewaters with the highest economic and environmental impact. The electrochemistry of diamond requires investigation under EAOP conditions. Better understanding of these reactions and the tradeoffs between cell design and electrode geometry will impact related applications including the electrochemical Synthesis and the development of compact systems for third-world potable water, desalination, and marine applications, and other On-Site Generation of advanced oxidants.