Grantee Research Project Results
2002 Progress Report: Dendritic Nanoscale Chelating Agents: Synthesis, Characterization, Molecular Modeling and Environmental Applications
EPA Grant Number: R829626Title: Dendritic Nanoscale Chelating Agents: Synthesis, Characterization, Molecular Modeling and Environmental Applications
Investigators: Diallo, Mamadou S. , Goddard, William A. , Johnson, James H. , Balogh, Lajos
Institution: Howard University , University of Michigan , California Institute of Technology
Current Institution: California Institute of Technology , Howard University , University of Michigan
EPA Project Officer: Hahn, Intaek
Project Period: May 1, 2002 through April 30, 2005
Project Period Covered by this Report: May 1, 2002 through April 30, 2003
Project Amount: $400,000
RFA: Exploratory Research: Nanotechnology (2001) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Nanotechnology , Safer Chemicals
Objective:
Dendrimers are highly branched nanostructures with controlled composition and architecture. Poly(amidoamine) (PAMAM) dendrimers possess functional nitrogen and amide groups arranged in regular "branched upon branched" patterns. This high density of nitrogen ligands enclosed within a nanoscale container makes PAMAM dendrimers particularly attractive as high capacity chelating agents for toxic metal ions [Cu(II)], electron transfer mediators [Fe(II)], redox active metal clusters [FeS], and metal clusters with catalytic properties [Pd(II)]. The objective of this research are to explore the fundamental science of metal ion uptake by PAMAM dendrimers in aqueous solutions, and assess the extent to which this fundamental knowledge can be used to develop: (1) high capacity and reusable chelating agents for industrial and environmental separations; and (2) FeS laden nanoparticles with enhanced reactivity, selectivity, and longevity for reductive detoxification of tetrachloroethylene (PCE) in aqueous solutions and subsurface formations.
Progress Summary:
During Year 1 of the project, we focused on the evaluation of PAMAM dendrimers with ethylene diamine (EDA) cores as high capacity and reusable chelating agents for use in environmental and industrial separation processes. To achieve this objective, we structured our research efforts around five tasks: (1) dendrimer synthesis and characterization; (2) measurements of dendrimer protonation in aqueous solutions; (3) measurements of metal ion uptake in aqueous solutions of dendrimers; (4) evaluation of a dendrimer enhanced ultrafiltration (DEUF) system for recovery of toxic metal ions from contaminated water; and (5) molecular dynamics (MD) simulations of proton and metal ion binding to dendrimers in aqueous solutions. The overall results of our experiments and MD simulations illustrate a key feature of dendritic nanoscale chelating agents: i.e., the covalent attachment of nitrogen ligands to conformationally flexible PAMAM chains enclosed within a nanoscale structure results in a substantial increase in binding capacity for metal ions with affinity toward N donors such as Cu[II]. Compared to traditional chelating agents and macrocycles with N donors, which typically bind one Cu(II) ion per molecule, G3, G4 and G5 EDA core PAMAM dendrimers with terminal NH2 groups can bind up to 115, 166, and 292 Cu(II) ions per mole of dendrimer at pH = 9.0, respectively. We also found that dendrimers can effectively be used in membrane-based ultrafiltration (UF) systems to achieve maximum metal ion retention without a significant loss in permeate flux. U.S. Environmental Protection Agency funding is being leveraged to develop and optimize the operation of a continuous bench scale DEUF systemwith a dendrimer recycling unit, for recovering metal ions (e.g., Cu[II], Zn[II] and Ni[II]) from industrial wastewater.
Future Activities:
The focus of our research activities in Year 2 of the project will be the synthesis and evaluation of redox active FeS dendrimer nanocomposites. PCE will be used as a model organic compound to test the hypothesis that these nanocomposites will exhibit enhanced reactivity for the reductive dehalogenation of chlorinated aliphatic compounds in aqueous solutions.
Journal Articles on this Report : 2 Displayed | Download in RIS Format
| Other project views: | All 41 publications | 10 publications in selected types | All 7 journal articles |
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Diallo MS, Christie S, Swaminathan P, Johnson Jr. JH, Goddard III WA. Dendrimer enhanced ultrafiltration. 1. Recovery of Cu(II) from aqueous solutions using PAMAM dendrimers with ethylene diamine core and terminal NH2 groups. Environmental Science & Technology 2005;39(5):1366-1377. |
R829626 (2002) R829626 (2003) R829626 (Final) |
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Diallo MS, Christie S, Swaminathan P, Balogh L, Shi X, Um W, Papelis C, Goddard III WA, Johnson Jr. JH. Dendritic chelating agents. 1. Cu(II) binding to ethylene diamine core poly(amidoamine) dendrimers in aqueous solutions. Langmuir 2004;20(7):2640-2651. |
R829626 (2002) R829626 (2003) R829626 (Final) |
Exit |
Supplemental Keywords:
polymer chemistry, materials chemistry, physical/theoretic chemistry, computational chemistry, molecular modeling, environmental chemistry, environmental engineering, chemical engineering, process engineering, environmental detoxification, groundwater remediation, pollution prevention, hazardous organics, industrial wastewater, membrane technology, polymer enhanced ultrafiltration, metal removal, nanocatalysts, water, soil, heavy metals, dense nonaqueous phase liquid, DNAPL, nanotechnology, waste reduction, waste minimization, dendrimers, environmental sustainability, environmentally applicable nonoparticles, groundwater, innovative technologies, innovative technology, membrane filtration, membrane-based, membranes, nanoscale chelating agents, nanotechnology, reductive detoxification, sustainability, tetrachloroethylene, PCE., Sustainable Industry/Business, RFA, Scientific Discipline, Water, Technology for Sustainable Environment, Ecological Risk Assessment, Civil/Environmental Engineering, Sustainable Environment, Environmental Chemistry, Engineering, Chemistry, & Physics, Chemistry and Materials Science, Biochemistry, New/Innovative technologies, Environmental Engineering, sustainability, dendrimers, detoxification, membrane technology, membranes, innovative technologies, environmental sustainability, membrane filtration, industrial wastewater, environmentally applicable nanoparticles, ultrafiltration system, nanotechnology, groundwater, PCE, membrane-based, reductive detoxification, innovative technologyProgress and Final Reports:
Original AbstractThe 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.