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Final Report: The Design of a Cost-Effective Titanium Dioxide Photo-Catalyst for the Removal of Arsenic in Drinking Water
EPA Grant Number: SU831832Title: The Design of a Cost-Effective Titanium Dioxide Photo-Catalyst for the Removal of Arsenic in Drinking Water
Investigators: Warner, John C. , Cannon, Amy , Duggan, John , Johnson, Abby , McGonigle, Michael , Mendum, Ted , Pyres, John
Institution: University of Massachusetts - Lowell , Wentworth Institute of Technology
EPA Project Officer: Nolt-Helms, Cynthia
Project Period: September 30, 2004 through May 30, 2005
Project Amount: $10,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity, and the Planet (2004)
Research Category: Pollution Prevention , Pollution Prevention/Sustainable Development
Description:
Objective:This project leverages emerging oxidative and adsorptive technologies that contribute to an extraordinary international mobilization to ameliorate the largest mass poisoning in human history. Three hundred million people are exposed to arsenic contaminated drinking water, at concentrations up to several hundred ppb - far in excess of the recommended limit 0.010 mg/l, primarily in rural villages throughout Asia. In the U.S., small communities, typically economically challenged and without municipal treatment facilities, must rally to respond to the new EPA mandate. We seek to deploy easy-to-use, easy-to-make, and easy-to-recombine, solid- state treatment modules to engage collaborators, complement competitive offerings, and foster user-led innovation.
Phase I of the project demonstrated the technical feasibility, of combining titanium dioxide nanoparticulate coatings with newly available ultraviolet Light Emitting Diodes as a photocatlytic oxidizer. This development secures a low bulk material cost option for an oxidant combining low-tech manufacturability with very infrequent maintenance. The oxidant converts arsenite to a more readily sequestered form - arsenate. Evaluations of the adsorptive capacity, of Zero-Valent Iron suggest that this emerging low cost option is a leading adsorptive module to combine with the photocatalyst. This form of iron is manufacturable from local scrap metal, and irreversibly binds inorganic forms of arsenic. Analysis indicates half a kilo of iron is enough to produce 7 liters of safe drinking water in around 8-10 hours with an estimated operational life of several years. Use of the will improve this performance.
Phase II calls for design and construction of system level prototypes in the first quarter in order to observe clean water production rates, estimate economic feasibility, deepen our appreciation of the science underlying the phenomena, and move to a broader consideration of performance requirements. Additional investigations include determining uptake of organic arsenic and the addition of antimicrobial coatings to prevent bacterial fouling.
Designing our photocatalysis module for reuse in other systems, and getting prototype modules into the hands of fellow researchers will contribute to the explosive growth of development capacity needed to address the arsenic crisis. We believe that enabling user-led innovation, in local enterprises, can have a powerful influence on lowering total cost of our oxidation module by simplifying manufacturing, evoking robustness in compatibility with local materials, and cultivating solutions that are culturally attuned and optimized for local conditions.
Summary/Accomplishments (Outputs/Outcomes):Photocatalyzed Oxidative Coatings
- Organic Aromatic Acid enabled Titanium Dioxide Nanoparticle coating technology, originated at the Center for Green Chemistry, was advanced in Phase I. A new formulation exhibits better coating characteristics than previously achieved. This resulted from a systematic investigation of the structure activity relationship of 87 formulations of coating additives based on organic aromatic acids.
- Pre-coating treatment of a Titanium derivative was found to enhance coat-ability of glass.
- However, dip coating of UV LEDs using the pre-coating and our previous best coating formulation performed poorly in the majority of cases. Further, the poorly coated LEDs exhibited additional failure after being operated in water.
- Coated glass slides demonstrated good stability in an arrangement with UV sources shining on the coating surface rather than through it. That suggests a design change is warranted to enable the more reliable configuration.
UV-LED Activated Oxidation
- The oxidative activity of a TiO2 nanoparticle suspension in the presence of UV @ 365nm was confirmed for lamp and LEDs using a proxy for arsenic - Orange Dye II. This method can serve as a control in studying diffusion in the coat-based system. However, the method was judged not to be reliable in quantifying the oxidative performance.
- The photoactivity of immobilized Ti02 films based on TiO2- carboxylic acid slurries, employing formulations developed by the Center for Green Chemistry, was confirmed.
- The decline in ODII concentration over time, using UV lamps as well as the UV-LED, is well fit by second-order exponential decay functions. This may imply two processes at play. for example absorption of the dye onto the tio2 then oxidation and bleaching of the dye. More refined experiments are required in Phase II to discern these effects.
Adsorption
- Compared to other arsenic removal technologies, this component could be considered a chemisorption approach in which the arsenic forms co-precipitates and mixed precipitates with iron. This is generally considered to be irreversible and thus amenable to landfill disposal. Speed and duration of performance is judged to depend on the surface to volume ratio of the iron particles. Investigation of these sensitivities seem warranted especially with respect to manufacturability in the developing world.
- The adsorption capacity of Arsenite on Zero Valent Iron, is calculated to be 0.16g As (III) / g Fe(O).
- The kinetics of the adsorption process are second-order in Arsenite. That is
the adsorption rate depends on the initial concentration of the contaminant.
Initially, there is a rapid reduction which slows significantly. To enable more
refined measurement and more efficient performance testing in Phase II, a Hydride
generator was acquired to fit an Atomic Adsorption Spectroscopy equipment has
been acquired which will enable studies down to the desired consumable concentrations.
Assembly
- As UV-LEDs are point sources, it is expected that their irradiation intensity declines with the square of the distance from the surface. So the initial design strategy was to coat the UV-LED itself. The experience of a significant different in coating glass topped LEDs versus glass prompted us to consider alternative arrangements which allows a thin film of contaminated water to flow between a coated surface and the UV source.
- Aromatic Acid enabled TiO2 coatings are a viable alternative to the use of polymer binders and high temperature sintering of TiO2 nanoparticles to immobilize coatings. Manufacturing will be cheaper, less energy intensive, and more environmentally benign.
- Tests were recently initiated on the more modular design separating the coated substrate and the UV-LED in proximity with contaminated water.
- UV intensity as a function of separation distance from the coated surface will dominate the dimensional constraints of physical instantiation.
- We have developed a formulation with better coating characteristics and higher durability than our previous best material. This will serve as the new model from here on. The effect of the currently preferred pretreatment and its interaction on a greater variety of substrates likely to be used in field manufacture ought to ensue.
- The rate of oxidation performance of the UV-LEDs as an energy efficiency and capital cost breakthrough.
- First stage analysis of the adsorptive component indicates 500g Fe (0) can remediate the recommended daily individual water requirement of 7.5 liters of water, contaminated at 500ppb, to l0ppb, in 8.3 hours. This amount should remain active at that load and at this performance requirement for a period of several years. Investigation of the adsorptive capacity for organic forms of arsenic should proceed.
- Evaluation of the effectiveness of the system with respect to other contaminants and microbes should commence in order to build the value proposition for the technology.
Proposed Phase II objectives and strategies:
Prototypes, modularized for lab use and simplified for field use, will help drive the formation of the extended alliances required for rapid deployment of this platform. Our preparatory experience in launching an enterprise to accelerate deployment of the technology suggests the need for an alternative to traditional Intellectual Property-based business model of technology transfer. A mode of organization and operation must be built to be more enabling of the developing world, such as the recently launched Science Commons initiatives. The second version plan for an enterprise to accelerate deployment of this technology should be completed prior to the start of phase II. This will have to be via a face-to-face collaboration strategic planning session of about 36 people.
The core network of collaborators will roughly double in size by the third quarter of Phase II harnessing the resources necessary to the foundation required post-Phase II. From an organizational perspective, the first two quarters will focus on connecting to NGOs already in the field, interfacing with developers of complementary technologies, and building the management network.
This collaboration began with the synergy of expertise in Water Quality Engineering and Environmental Chemistry at Wentworth Institute of Technology with core competencies in photochemistry, solid-state processing, and nanoparticle coatings at the Center for Green Chemistry at the University of Massachusetts. An enabling enterprise, PEC Coating Technologies, is being launched via a series of events which began with competing in the MIT Enterprise Forum in March 2004. The team engaged business leadership from the Entrepreneurship Program at Babson College and looks forward to deepening the relationship. The Environmental Business Technology Center is helping to cultivate a Board of Directors and Technical Advisors. In phase II we anticipate developing strategic alliances with select members of the Green Chemistry community with complementary technologies, and NGOs and agencies already engaged with end-users. Towards that end, The Green Light Foundation in partnership with Sustainability Knowledge Network Inc. will design a collaborative infrastructure.
Journal Articles on this Report: 1 Displayed | Download in RIS Format
| Other project views: | All 6 publications | 1 publications in selected types | All 1 journal articles |
| Type | Citation | ||
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Cannon, Amy, Warner, John, “Structure Activity Relationship of Organic Acids in Titanium Dioxide Nanoparticle Dispersions”, ACS Journal - Chemistry of Materials, Vol. 16, No. 24: November 30, 2004 pp 5138—5140. |
SU831832 (Final) |
not available |
Media, groundwater, drinking water, Risk Assessment, drinking water contaminants,
poisoning, carcinogen, Pollutants: toxics, metals, arsenic, Risk Management:
treatment, remediation, detoxification, arsenic removal, Public Policy: Regional
Economic Development, microenterprise, international cooperation, Science Commons,
Scientific Disciplines: Civil & Environmental Engineering, Water Quality,
Green Chemistry, Analytic Chemistry, Organic Synthesis, Environmental Chemistry,
Mechanical Engineering, Electrical Engineering, Chemical Engineering, Sustainable
Business, Methods/Techniques: clean technologies, energy efficiency, catalysis,
photocatalytic oxidation, thin films, coatings, titanium dioxide nanoparticles;
chemisorption, adsorption, co-precipitation, zero valent iron, UV light emitting
diodes,
,
POLLUTANTS/TOXICS, Water, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Sustainable Industry/Business, Scientific Discipline, RFA, Arsenic, Technology for Sustainable Environment, Sustainable Environment, Drinking Water, Chemical Engineering, Technology, Water Pollutants, Environmental Chemistry, New/Innovative technologies, Environmental Monitoring, drinking water system, drinking water contaminants, treatment, environmental sustainability, UV light emitting diodes, clean technologies, arsenic removal, green chemistry, drinking water distribution system, photocatalyst, activated carbons, adsorption, detoxification, other - risk assessment, drinking water treatment, green engineering, drinking water treatment facilities
Relevant Websites:
http://greenchemistry.uml.edu/html/whatsnew/whatsnew.html 
http://www.sknworldwide.com/
Progress and Final Reports:
Original Abstract