New process to improve water decontamination
A new method has been developed by engineers that is capable of selectively removing micropollutants from water.
Relying on an electrochemical process, the method can extract even very low levels of unwanted compounds in water; such as pesticides, chemical waste products and pharmaceuticals.
Existing methods for separating extremely dilute concentrations of pollutants from water are energy and chemical-intensive when compared to the new method, formulated by Massachusetts Institute of Technology (MIT).
As well as allowing for organic contaminants to be removed selectively, the new approach’s electrochemical process also negates some key limitations of conventional separation methods, such as fluctuations in the levels of acidity and competing surface reactions causing losses in performance.
The membrane filtration included in current systems for dealing with dilute contaminants is also expensive, with a reduced level of efficiency at low concentrations.
Additionally, MIT postdoc, Xiao Su, says that the current contamination methods using electrodialysis and capacitive deionisation can produce side reactions due to the high voltages required.
In the new approach, water runs between surfaces that have been chemically treated; allowing them to act as positive and negative electrodes. The surfaces are covered with faradaic materials - which after undergoing reactions to give them a positive or negative charge - can be tuned to attract specific contaminant molecules.
This system allows for positive and negative toxic ions to be removed from contaminated water simultaneously.
“A similar selective removal process could be used to recover compounds of a high value in a chemical or pharmaceutical production plant,” Su says.
“These compounds might otherwise be wasted. The system could also be applied during environmental remediation, toxic organic chemical removal, or when recovering value-added products in a chemical plant.
“For remote areas in the developing world, where the water supply is often polluted by pesticides, dyes and chemicals, this should also prove a useful water purification system.”
A patent application for the new process has been lodged by its researchers.