Advanced Nanosensors for Continuous Monitoring of Heavy MetalsEPA Grant Number: R830906
Title: Advanced Nanosensors for Continuous Monitoring of Heavy Metals
Investigators: Sadik, Omowunmi , Wang, Joseph
Current Investigators: Sadik, Omowunmi , Mulchandani, Ashok , Wang, Joseph
Institution: The State University of New York at Binghamton , New Mexico State University - Main Campus
Current Institution: The State University of New York at Binghamton , New Mexico State University - Main Campus , University of California - Riverside
EPA Project Officer: Hahn, Intaek
Project Period: May 19, 2003 through April 18, 2006
Project Amount: $351,000
RFA: Environmental Futures Research in Nanoscale Science Engineering and Technology (2002) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
Metals in the environment are becoming a major environmental concern especially in drinking water. Conventional approaches for detection are expensive and non-field-deployable. This research will utilize novel nanostructured materials in ways that might be exploited in sensing technologies for the detection, identification and quantitation of metals. The overall objective is to utilize novel colloidal-metal nanoparticles that are incorporated into a bed of electrically conducting polymers (ECPs) for the development of nanosensors. Specific objectives include: (1) Preparation, characterization, and optimization of colloidal metal nanoparticles sequestered within conducting polymers using photochemical polymerization. The resulting materials will be tested for the design of metal nanosensors. (2) Design and testing of the novel nanosensors for the identification, detection, speciation and quantitation of heavy metals. (3) Fabrication of disposable nanosensors/nanochips using NMSU Nanofabrication facility and utilization of the sensor for the analysis of metal ions from aqueous effluents.
In analogy to integrated circuits derived from semiconductors in which millions of microcircuits are located on a small silicon chip, this metal sensor can be viewed as comprising millions of identical, elementary, molecular active sites of nanoparticles generated through nanotechnology and tailored to meet specific environmental needs. The inclusion of the nanoparticles will establish catalytic sites that will facilitate the electrodeposition of the corresponding metal ions of interest. In order to enhance sensor performance for selective metal ion detection, we will control the polymerization conditions by incorporating the covalent attachment of amine functionality, dimercaptoethanol, S-carboxymethyl-L- cysteine and 4-(2 pyridylazo) ligands. The analysis of the metal ions will be achieved by using anodic stripping voltammetry and atomic absorption spectroscopy. Since the toxicity of a given concentration of heavy metal present in natural water depends on speciation, the proposed method will be controlled for metal speciation using pH, the amount of dissolved and suspended nanoparticles, and applied potential. Thereafter, the sensor will be used for the determination of EPA's priority metal contaminants such as iron, arsenic, nickel, cadmium, mercury, lead, chromium and copper from aqueous streams. Preliminary results using custom-designed ECPs showed remarkable metal sensitivity in the parts-per-trillion levels. The nanosensor will be regenerated using a potential step where the applied potential is reversed and the solution reservoir at the outlet of the sensor is changed, thereby providing a continuous and uninterrupted detection of the metals.
This research involves new approaches that will enable the atomic and molecular control of colloidal-metal nanoparticles as building blocks of advanced materials for environmental sensing applications. The immediate benefits will include the development of a small-scale, nanosensor, novel nanomaterials, and a new method for detecting toxic metals from the environment. The materials will allow the fabrication of nanochips for metals sensing. These chips may be used for personal metal monitoring by field workers, thus protecting these workers and allowing immediate decisions on remediation efforts. Ultimately, the project will reduce human exposure to toxic metals, in groundwater, industrial effluents, and run-offs, thus improving human health and the environment.