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Grantee Research Project Results

Grantee Research Project Results

Semiconductor Photocatalytic Electrospun Nanofiber Mats as a Green Filter Media for Removal of Heavy Metals from Ground Water

EPA Grant Number: FP917480
Title: Semiconductor Photocatalytic Electrospun Nanofiber Mats as a Green Filter Media for Removal of Heavy Metals from Ground Water
Investigators: Lounsbury, Amanda W
Institution: Yale University
EPA Project Officer: Zambrana, Jose
Project Period: August 1, 2012 through July 31, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012)
Research Category: Academic Fellowships , Fellowship - Environmental Engineering

Description:

Objective:

Many smaller U.S. public water systems (PWS) already are struggling to meet existing regulations and probably will not meet newer regulations without radical innovative changes in current technology. Best available treatment practices often are contaminant specific, energy, chemically and/or financially intensive, toxic and non-renewable, thereby imparting even greater challenges for these small-scale PWS. As an initial step towards the goal of a sustainable, adaptable, multipurpose and costeffective drinking water treatment system, this project will focus on the development of a robust filter medium that simultaneously remediates arsenic and chromium, two priority heavy metals prevalent in ground water and of concern for human health and the environment. This work will focus on the removal of arsenic and chromium using non-toxic, photocatalytic nano-TiO2 and nano-α-Fe2O3 functionalized electrospun chitosan nanofibers for the safe and reliable delivery of drinking water by small-scale PWS.

Approach:

The first stage of the project will be the electrospinning and characterization of combined chitosan/semiconductor nanofiber mats. At first, the semiconductor will be embedded within the chitosan and then the semiconductor will be coated on top of the embedded nanofibers. The second stage of the project will assess the ability of neat and electrospun semiconductor photocatalytic nanomaterials to remove arsenic, chromium and a mixed solution of arsenic and chromium from synthetic ground water in the presence and absence of ultraviolet (UV) light. The third stage will determine the environmental impact and robustness of the more effective filter combination for removal of arsenic and chromium as compared to current small-scale water treatment systems.

Expected Results:

TiO2-chitosan and α-Fe2O3-chitosan nanofiber mats will be effectively electrospun and coated. The nanofiber mats will maintain successfully the photocatalytic and adsorption properties associated with the neat nanoparticles. All mechanisms will react and remove arsenic and chromium with a higher efficiency in the presence of UV light. Due to increased surface area, coated nanofibers will be better able to remove arsenic and chromium than non-coated fibrous mats. Oxidation/reduction of individual arsenic and chromium solutions will be pH-dependent because of the zero point charge of α-Fe2O3; however, arsenic may act to stabilize the electron/hole pair of α-Fe2O3, thereby increasing the oxidation/ reduction of arsenic and chromium in a mixed solution. The use of the nanofibers in a small-scale system will have a lesser cost and environmental impact as compared to traditional small-scale treatment systems over the life of the system.

Potential to Further Environmental/Human Health Protection

A culturally based appropriate technology transfer of electrospun photocatalytic semiconductor nanofibers as one component of a green, sustainable and cost-effective multi-component system will allow small PWS to meet consistently more stringent water standards with lesser environmental impact and without having to replace costly technology. It also will provide people relying on small PWS with a source of clean water. A system of this sort will have a large impact on Native American reservations and peri-urban zones that are expanding at a rapid rate throughout the developing world.

Supplemental Keywords:

nanofiber, ground water contaminants, public water system

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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