Final Report: Nanocomposite-Based Filter for Arsenic Removal in Drinking WaterEPA Contract Number: 68D02095
Title: Nanocomposite-Based Filter for Arsenic Removal in Drinking Water
Investigators: Radhakrishnan, R.
Small Business: Materials Modification Inc.
EPA Contact: Manager, SBIR Program
Project Period: October 1, 2002 through July 31, 2003
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2002) RFA Text | Recipients Lists
Research Category: Nanotechnology , Water and Watersheds , SBIR - Water and Wastewater , SBIR - Nanotechnology , Small Business Innovation Research (SBIR)
The goal of this Phase I research project was to develop a nanocomposite filter made from naturally available materials. Arsenic is discharged into waterways from both natural (runoff from mines) and industrial sources (ranging from semiconductor manufacturing to processing of wood, paper, pigments, and even pharmaceuticals). Although the most common toxicity associated with arsenic is through ingestion of contaminated food and water, it also can occur via inhalation or skin absorption. Once absorbed, arsenic is distributed throughout the body tissues, including the liver, other abdominal viscera, bone, and skin.
An intake of approximately 60 ppm of arsenic can be fatal. Prolonged exposure to lower levels may cause skin pigmentations, keratoses, and skin cancers. Chronic exposure to arsenic, particularly to the trivalent form, manifests itself by weakness, weight loss, nausea, diarrhea, constipation, skin disorders, hair loss, abdominal pain, pleuritis, and peripheral neuritis. Numerous studies indicate that arsenic compounds, including arsenic trioxide, can cause cancer of the skin, liver, lung, and possibly the lymphatic system. As a result of this growing health concern, the U.S. Environmental Protection Agency (EPA) has established a health-based, non-enforceable Maximum Contaminant Level Goal of zero for arsenic and an enforceable Maximum Contaminant Level of 0.01 mg/L (10 ppb). This new rule is to take effect starting in January 2006. To comply with this directive, there is an urgent need to develop new, simple, and effective treatment systems to remove arsenic from water. Although the EPA has recognized a few techniques as "Best Available Technologies" (BATs), there are opportunities to improve the efficiencies of these BATs even further and make them more easily adaptable.
The primary focus of the present effort was to develop a nanocomposite filter for arsenic removal. The nanocomposite was to be prepared from naturally occurring materials. The two materials were prepared in the nanocrystalline form and characterized for their composition, particle size, and particle morphology. The nanocrystalline materials were mixed in various ratios to form a nanocomposite. The powders were consolidated using plasma pressure consolidation and pressureless sintering to obtain compacts with varying levels of porosity. Studies on arsenic removal efficiency were conducted on powders as well as consolidated compacts. Spiked feed waters containing 300 ppb of As(V) and As(III) were separately filtered through the above materials. The filtered water samples were analyzed for arsenic concentration using inductively coupled plasma mass spectroscopy.
The nanocomposite was able to reduce the arsenic concentration from an initial level of 300 ppb to less than 10 ppb. The significant advantage of this technology is the low cost of the filter. Because the filter is prepared from naturally available materials, the cost per pound of the raw materials will be under $0.40/lb. In addition to the experimental work carried out during Phase I, Materials Modification, Inc., provided information on the project and technology to Foresight Science and Technology, for preparation of a technology assessment report. The assessment provided a comprehensive report on the market, competition, and regulatory requirements to be met by the technology as well as economical factors that dictate the successful entry into the market.