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Research Description
Atwood group research is focused on fundamental and applied aspects of inorganic and main group metals. This work involves the design and synthesis of ligands with specific affinity for the targeted metal and creating a detailed fundamental understanding of the structure, bonding, and reactivity of the metal-ligand combinations. Subsequently, we look for applications to use the compounds in. This might be catalysis or the creation of new materials (for the aluminum chemistry) or the remediation of contaminants such as Cd, Hg, Pb, and As from water (for the environmental chemistry).
Graduate and undergraduate students working on these projects are trained in a wide variety of inorganic synthetic techniques and analytical characterization methods. This provides them with the necessary background to be successful in academics or industry. Some recent graduates include Matthew Krepps (Ph.D. 2002, Associate Prof. Lee Univ., TN), Yuzhong Wang (Ph.D. 2002, Research Associate, Univ. of Georgia), Timothy Keizer (Ph.D. 2002, Nalco Inc. IL), Amithaba Mitra (Ph.D. 2006, Postdoctoral Associate, Univ. of Wisconsin-Madison), Mohan Bharara (Ph.D. 2006, Postdoctoral Auburn University, AL), Aaron Hutchison (Ph.D. 2007, Assistant Prof. Cedarville Univ. OH).
The current research group consists of Graduate Students, Lisa Blue, Kamruz Zaman, Eduardo Santillan, Niladri Gupta, Partha Jana, Christopher Preece and Undergraduates, Kristen Bird, Seth Heupel, Kateland Beals, and Lance Stanton.
I. Inorganic Research
A. Chelated Aluminum Cations
For many years now we have been exploring the synthesis and characterization of cationic group 13 compounds with potential applications in polymerization and Lewis acidic transformations. Recently we discovered that some of these cations effect the complete dealkylation of phosphate esters (publication 112). It was subsequently found that aluminum cations, supported by the tetradentate salen ligands were more effective in this reaction. We have demonstrated that the aluminum chelates can be used to destroy or deactivate nerve gas agents and pesticides. We are currently exploring the use of the compounds to remove nerve gas agent simulants in the gas phase. The powerpoint presentation on this work is listed as a separate link. Publications 141 and 146 describe the latest developments we have published on this project.
B. Molecular Precursors to Nanoparticulate Alumina
We have created a new class of tetradentate compounds having the appropriate Al:O stoichiometry for the formation of Al2O3. These molecules have tri-diamond shape that is the emblem of the Mitsubishi Company and so we refer to them as "Mitsubishi Molecules". See publication 94 for a review of this class of molecules. They can be hydrolyzed in organic solvents to produce nanoparticulate alumina. In this reaction it appears that the Mitsubishi molecule acts as template for the formation of alumina, rather than hydrated forms of alumina. Publication 135 describes this work in detail. They can also be used under anaerobic conditions to deposit a corrosion resistant covering layer on metal substrates. In a further development we have used the nanoparticulate materials to create alumina-Pepsin hybrids that are heterogeneous but maintain the activity of the enzyme (publication 126). The powerpoint presentation on this work is listed as a separate link.
C. Prevention of Dross Formation in Molten Aluminum
Literature from several decades ago revealed that adding small amounts of boron reagents to molten aluminum dramatically inhibited the formation of aluminum oxide. We have extended this work to propose an explanation for this observation. We hypothesize that the added boron acts to prevent the transformation of MgO to MgAl2O4 by forming a covalent bond to the corners of the MgO crystallites. This would account for the fact that part-per-million levels of the boron reagent have such an inhibitory effect on the oxidation. This is a key step in the dross formation reaction as "breakaway oxidation" of aluminum does not occur until after the spinel forms. The spinel appears to act as a conduit for the accelerated oxidation of aluminum. The attached powerpoint presentation describes our efforts to characterize the dross inhibition effect. We are currently seeking licensees for the patent on this project.
II. Environmental Research
A. Heavy Metal Remediation
One of the preeminent mercury binding compounds known today is benzenediethanethiol (BDT) for which a great deal of information is known (see the publication list). BDT has been shown to irreversibly bind Hg under a wide range of laboratory conditions as well is in the field for mercury removal from gold mining effluent (publications 114 and 121), a variety of metals from acid mine drainage (publication 120), lead from lead-battery recycling effluent (publication 113) and for soil-borne mercury (publication 128). The bonding to Hg in BDT has been determined to be linear in a 2007 publication (publication 151), and the BDT-Hg compound shows no leaching under both basic and acidic conditions. BDT also binds Cd and Pb in a similar manner and produces non-leaching precipitates. A powerpoint presentation on this work is included on this website.
B. Acid Mine Drainage Prevention
BDT has been demonstrated to prevent the release of iron and other metals from coal. This is described in publication 129. We believe the BDT molecule binds the surface Fe atoms in pyrite through covalent bonding. This is a similar effect to what was observed in the prevention of aluminum oxidation (through covalent binding of the boron additive to the MgO crystallites). The environmental powerpoint presentation contains information on this effect. It should be possible to use this technology to prevent acid mine drainage in newly abandoned coal mines. Solutions of BDT could be sprayed onto the walls of the mine leaving a long-lived covalent coating on the exposed mine surface. Subsequent flooding of the mine would not dissolve the BDT as it is hydrophobic. We are currently seeking collaborators who can demonstrate this technology in a actual coal mine.
C. Groundwater Arsenic From Poultry Operations
Arsenic containing feed additives have been used extensively in past decades to improve the weight of the poultry and to control intestinal parasites. The poultry waste is used as fertilizer on agricultural fields and may potentially be found in the resulting groundwater runoff. We have characterized the extent of arsenic contamination in several fields in Western Kentucky and found the levels to be on the order of parts-per-billion. We are currently conducting a study on the arsenic content of the groundwater emanating from these fields.
D. Arsenic Filtration Columns
We have created a new filtration unit containing a proprietary set of compounds that effectively removes As(III) from water. The column also traps any As(V) present by converting it to As(III) which is then bound by the proprietary reagent. In laboratory studies we have demonstrated that water containing ppb levels of As can be purified so that the effluent contains less then 1 ppb As. We have demonstrated this further on water obtained on-site in West Bengal, India. We are currently working with philanthropic agencies to implement this filtration system in India and Bangladesh and thus hope to save the hundreds of millions of people there from the horrors of As poisoning. Patents and publications on this work are pending.
E. Real-Time Monitoring of Environmental Contaminants.
In collaboration with Quansor, Inc. we are developing new sensors for the real time detection of inorganic, biological, and organic contaminants in water. The system is proprietary but has the capability of determining the levels of specific contaminants in the field and sending the information by cell-phone technology to a central monitoring station.
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