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Analytical Chemistry
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[Recent Publications] Recent Publications



Professor

GARY W. VANLOON

B.Sc., 1962, McMaster University;

Ph.D., 1967, University of Toronto.    

(613) 533-2633

e-mail: vanloon@chem.queensu.ca 

 

 

 

 

 

 


Information about
Environmental
Chemistry

 


Research Activities

Research in our laboratories covers two different areas. The first is related to drinking water and waste water treatment chemistry. In the case of drinking water, alum (an aluminum compound) is commonly used as a coagulant to remove dissolved and suspended impurities in order to produce clean and aesthetically pleasing water for public consumption. Alum is an efficient coagulant but it leaves behind a small residual of aluminum – one tenth of a part per million or less - in the finished water. Except when the water is used for medical dialysis, such low aluminum concentrations are not known to cause any cute medical disorders in humans. In recent years, however, some scientists have speculated that there is a connection between Alzheimer's disease and chronic exposure to low concentrations of aluminum. While this theory remains unproved, it has spurred interest in the development of alternative coagulants. We are concentrating on studies of other aluminum-based compounds, some of which we synthesize in our lab. For certain types of water, they function as efficiently as or better than alum and at the same time, leave a much smaller residual aluminum concentration in the water. Full scale plant tests have been carried out onone of our products and a Canadian patent is pending.

The work on wastewater deals with a different issue. As in drinking water, alum is used to remove suspended material, but it also is an effective dephosphorizing agent. Removal of phosphorus from wastewater before it is discharged into a lake or river is of key importance, since excess phosphorus in water bodies leads to eutrophication. This shows up in the form of algal blooms and reduces the quality of the water body. Our studies are designed to understand how alum functions as an agent for phosphorus removal. We are particularly interested in studying the nature of the solids that precipitate out of solution under various conditions. As tools for this purpose, we use a spectrophotometric-kinetic procedure, NMR and IR spectroscopy and surface microscopy procedures. With a better understanding, it may be possible to design conditions which are more efficient so that there will be a smaller amount of residual phosphorus discharged after treatment.

 The second type of project is a study of the environmental behaviour of particular pesticides and other small organic molecules in soil and water. Pesticides are, by nature, toxic to some living organisms. The ideal pesticide will eliminate the plant or animal pest, but will not affect other non-target organisms. Therefore, it is essential that we understand how the pesticide degrades as well as how it and its degradation products move about in soil and water. We are developing methods, mostly using liquid chromatography as a tool, which enable simultaneous study of both these factors. In particular, we are examining how pesticides interact with different types of soil, and the way in which the interactions determine their mobility and stability.

In a related study, we are examining the possibility of using modified cyclodextrins (CDs) for mobilizing some hydrophobic compounds that are present in the subsoil in the form of dense non-aqueous phase liquids (DNAPLs). Being relatively benign natural products, CDs have the potential of replacing some surfactants in the role of enhancing movement of organic compounds by increasing their solubility in groundwater. Cyclodextrins used In this way, could enhance the fficiency of passive or pump-and-treat groundwater remediation procedures.

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