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

EPA Contract Number: EPD11053
Title: Development of a Scalable, Low-Cost, Ultrananocrystalline Diamond Electrochemical Process for the Destruction of Contaminants of Emerging Concern (CECs)
Investigators: Arumugam, Prabhu
Small Business: Advanced Diamond Technologies Inc.
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: March 1, 2011 through August 31, 2011
Project Amount: $79,995
RFA: Small Business Innovation Research (SBIR) - Phase I (2011) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Drinking Water Treatment and Monitoring

Description:

The primary goal of this project was to demonstrate a scalable, commercial-ready, low-cost anodic oxidation technique using large area boron-doped ultrananocrystalline diamond (BD UNCD) electrodes for purification of water containing Contaminants of Emerging Concern (CECs).

Summary/Accomplishments (Outputs/Outcomes):

The successful achievements of this Phase I project were as follows:

1) Demonstrated superior electrode reliability on medium-sized (3.2 x 3.2 cm) and large area Ta and Nb electrodes (18 × 15 cm) under accelerated life-test protocols -- i.e., 2.0-2.5 A/cm2, equivalent to more than 25 years at 150 mA/cm2 and under actual operating conditions for on-site generation (OSG) of chlorine, i.e., 450 mA/ cm2, for more than 2,500 hours of almost continuous operation.
2) Confirmed no electrode material loss and no significant changes in surface morphology as determined by SEM, optical microscopy, Raman spectroscopy and differential pulse voltammetry after current stress of more than 1,500 hours at 450 mA/cm2.
3) Established an optimal treatment protocol for highly efficient/low-cost oxidative destruction of the difficult-to-destroy pharmaceutical 17ß-estradiol across a wide range of concentrations, current density, flow and electrolyte conditions.
4) Succeeded in reliably detecting 1 ppm estradiol using two complementary methods:  (a) UV-Vis spectroscopy and (b) electrochemically with 200 μm-diameter UNCD microelectrode arrays. The lowest concentration detected was 10 ppb.
5) Estimated the total cost (operating+capital) of $4.00 - $14.00/tonne to destroy estradiol of 1-100 ppm with the cost of diamond being the primary cost driver. This is at least 10 times less expensive than other advanced oxidation processes (AOPs).
6) Discovered the importance of a newer electrode surface in reducing the time to destroy a given concentration of estradiol and the operating and capital costs by a factor of 4, presumably due to a higher rate of hydroxyl radical generation.

Conclusions:

All objectives described in the Phase I proposal were met or exceeded. In particular, electrode lifetime and estradiol oxidation rate data are indicative of a low-cost electrochemical AOP (EAOP) that appears to be more easily scalable, reliable and commercial ready than any other AOP process on the market. According to a conservative cost analysis using well known UNCD production costs, ADT will be able to offer these durable and versatile electrodes to the market at a cost point significantly below that of any other diamond film electrodes. Existing non-diamond electrodes such as platinum, lead dioxide and tin dioxide are not capable of electrogenerating hydroxyl radicals and other forms of active oxygen (hydrogen peroxide and ozone) with high current efficiency and high catalytic activity as compared to diamond. Thus, on a cost plus performance basis, UNCD electrodes have the potential of displacing current AOP electrodes. OSG operation has been confirmed with electrodes of 100 cm2 active area, and this is a sufficiently large size to enable low-volume commercial applications of UNCD-based EAOP. ADT reliably can deposit diamond on electrode areas as large as 1,000 cm2, which is a sufficiently large electrode format to support medium-high volume applications (up to 100 tonnes of waste per day per cell of this size depending on current density).

Commercialization:  Technology Niche AnalysisTM performed by Foresight Science & Technology believes that there are many potential areas where the technology would better meet the current needs of the market. For example, in the wastewater market, pesticides are still a big problem in agriculture and fracking chemicals used in the natural gas industry are a large concern for drinking water supplies. Also, disinfection byproduct reduction is a large unmet need for the drinking water market. Foresight contacted more than two dozen small- to medium-sized wastewater service and/or equipment manufacturing targets on behalf of ADT. Two large water market players showed interest in UNCD technology. ADT is holding ongoing discussions with one of them at the current time. In particular, three key factors were identified from this effort:  (1) energy consumption and efficiency (primary consideration); (2) disinfection capabilities, specifically microbes and viruses; and (3) formation of disinfection byproducts, which will be studied in more detail in Phase II. ADT already has started to compile the electrical energy consumption information that will be used to attract potential customers to try UNCD technology. Microbial tests have been performed in a third party laboratory to assess the disinfection capability of oxidants generated by the UNCD cell, and this work has demonstrated a large improvement over existing methods of production of oxidants for disinfection. This work will need to be extended to a larger array of potential system operating parameters and for a larger array of pathogens. Lastly, the formation of disinfection byproducts (for the drinking water market), which is a large area of concern and currently an unmet need in the industry, will be addressed. Foresight provided feedback from customers on the importance of system reliability and that users will require these systems to run for at least 30 years. This is again where the exceptional reliability of UNCD electrodes will provide a huge competitive advantage.
 
ADT will adopt the following recommendations for commercialization provided by Foresight Science & Technology. First, third party data will be required to demonstrate that the system operates in an actual application at the same level of performance demonstrated in the laboratory. This will be required to obtain interest from any municipality to evaluate the system. Second, ADT will partner with an existing waste treatment service or equipment provider by providing the capital equipment at cost or free of charge in return for receiving ongoing performance data and support for access to the market. It is likely that such a demonstration would avoid the west coast, where salt contamination is a major issue, since EAOP does not desalinate. However, an increase in the salt concentration leads to an increased rate of destruction and a lower overall cost of treatment because less diamond is required. The primary goal is therefore to demonstrate a cost-effective, commercial-level solution, which already has been demonstrated in ADT's laboratory. Scale-up will be required for Phase II. Finally, it is likely that the initiation of a relationship with regional and national water associations would be advantageous because the water industry, and more particularly municipalities, are very conservative and slow to adopt new technologies.
 
Meanwhile, ADT already has initiated discussions on its own with several companies within and outside the United States. During the past 2 months, ADT has sold UNCD electrodes to a number of companies generating significant sales revenue and provided quotes to a large number of future customers. System-level water treatment discussions have been a prominent feature of these discussions, and customer requirements are becoming much clearer as a result. To further increase revenue flow and strategic advantage, ADT also is in the process of developing electrochemical cells and systems in addition to electrodes (details will be discussed in Phase II).

Supplemental Keywords:

low-cost process, drinking water, water purification, Contaminants of Emerging Concern (CECs), anodic oxidation,  boron-doped ultrananocrystalline diamond (UNCD®) thin films

SBIR Phase II:

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