Impact/Purpose:

Appropriate technologies are needed for drinking water problem in the developing world. An estimated 1.1 billion people worldwide lack access to safe drinking water. This is a global problem. The purpose of our research is to develop a self-sustaining and an inexpensive reactor that will rid the naturally available water from a wide variety of contaminants and pathogens, making it suitable for human consumption.

Description:

The Ti0₂ based purification system reactor was built and tested by various diagnostic techniques for its efficacy in detoxification of water against organic and biological matter. Initial experiments were done with ultraviolet lamp as excitation source for photo-catalysis. Substrate immobilized nano-porous TiO coated over glass and ceramic tiles were developed as catalysts. Various compositions of binders and TiO₂ loading were tried and evaluated for optimized performance. This mitigates the problem of removing ultra fine semiconductor particle suspension from the purified water. To develop self purifying storage vessels for water, we developed and tested TiO₂ sputter processed coatings, which can be embedded over vessel surface. This approach has potential to realize stand-alone reactors that would require nb electricity or chemical additives and provide clean water on demand at any location. In various tests we have conducted clean water was spiked with varying concentrations of methyl blue dye.
Various TiO₂ embedded discs were suspended for varying periods in a reactor filled with spiked water. The TiO₂ catalyst was very successful in speeding up the oxidation process of methyl blue and this was verified visually and more quantitatively by using spectrometric determinations. The microbial tests were performed on heterotropic bacteria that are naturally present in stagnant water such as po4ds. Utilizing Ti02 catalyst plates, water samples drawn from the reactor at various times showed remarkable decrease in the concentration of bacterial colonies. In about 4 hours of photo-catalysis, complete eradication of microbial matter from the water was realized.

We have looked into scientific concepts governing the use of oxide semiconductors for toxic water remediation. More important of these is inefficient separation of the charges generated by the UV light irradiation which translates into low quantum efficiency of the process. Therefore mechanistic aspects of photo-catalytic oxidation property of wide band gap semiconductor materials such as TiO₂ and ZnO to degrade organic wastes in the water was investigated to find ways to improve the catalyzing efficiency and to develop novel materials for optimum results. The mechanism we visualize is the two-step electron reduction process. The conduction electron first produces 0H radical, which injects hole in the semiconductor valence band enhancing the luminescence. 0H radicals are produced by oxidation of 4iethanol and water. These data are suggestive of alternative charge exchange processes at the semiconductor interface with the toxic substances. More investigations are however needed to establish the processes. Such knowledge is relevant for improving the quantum efficiency of the photo-catalytic process.

URLs/Downloads:

Final Progress Report

Record Details:

Record Type:PROJECT( ABSTRACT )

Start Date:10/01/2004

Completion Date:05/30/2005

Record ID: 88146

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Related Organizations:

Role :OWNER

Organization Name :UNIVERSITY OF MASSACHUSETTS - AMHERST

Citation :Amherst

State :MA

Zip Code :1003

Project Information:

Approach :

Based on our initial laboratory tests we showed that UV-A radiation from sunlight, when used in conjunction with photo-catalyst titanium oxide (TiO2), is able to remove certain pathogens and chemicals from water. The technical challenges are in developing an algorithm to maximize the affectivity variable UVA intensity from the sun as it activates catalysis; a robust TiO2 embedded reactor that is self-sustaining; and a cost effective process. We also need to develop a stable reactor that can be produced inexpensively. Practicality of such approach will help in diminishing the severe drinking water crisis in the developing countries and also its availability in the rural/remote areas in developed countries.

We will develop an algorithm to inter-relate key process variables, sunlight intensity, temperature, types of photocatalyst and various organic and biological contaminants and use it in understanding mechanisms responsible for their removal. Data gathered from such experiments will facilitate the development of an optimum reactor and reliable water disinfection process.

Cost :$10,000.00

Research Component :Pollution Prevention/Sustainable Development

Risk Paradigm :RISK ASSESSMENT

Approach :

Based on our initial laboratory tests we showed that UV-A radiation from sunlight, when used in conjunction with photo-catalyst titanium oxide (TiO2), is able to remove certain pathogens and chemicals from water. The technical challenges are in developing an algorithm to maximize the affectivity variable UVA intensity from the sun as it activates catalysis; a robust TiO2 embedded reactor that is self-sustaining; and a cost effective process. We also need to develop a stable reactor that can be produced inexpensively. Practicality of such approach will help in diminishing the severe drinking water crisis in the developing countries and also its availability in the rural/remote areas in developed countries.

We will develop an algorithm to inter-relate key process variables, sunlight intensity, temperature, types of photocatalyst and various organic and biological contaminants and use it in understanding mechanisms responsible for their removal. Data gathered from such experiments will facilitate the development of an optimum reactor and reliable water disinfection process.

Cost :$10,000.00

Research Component :OTHER

Risk Paradigm :RISK ASSESSMENT

Approach :

Based on our initial laboratory tests we showed that UV-A radiation from sunlight, when used in conjunction with photo-catalyst titanium oxide (TiO2), is able to remove certain pathogens and chemicals from water. The technical challenges are in developing an algorithm to maximize the affectivity variable UVA intensity from the sun as it activates catalysis; a robust TiO2 embedded reactor that is self-sustaining; and a cost effective process. We also need to develop a stable reactor that can be produced inexpensively. Practicality of such approach will help in diminishing the severe drinking water crisis in the developing countries and also its availability in the rural/remote areas in developed countries.

We will develop an algorithm to inter-relate key process variables, sunlight intensity, temperature, types of photocatalyst and various organic and biological contaminants and use it in understanding mechanisms responsible for their removal. Data gathered from such experiments will facilitate the development of an optimum reactor and reliable water disinfection process.

Cost :$10,000.00

Research Component :P3 Challenge Area - Water

Risk Paradigm :RISK ASSESSMENT

Project IDs:

ID Code :SU831833

Project type :EPA Grant