Since all heavy metals are
non-biodegradable, they must be removed from the polluted streams
for the environmental quality standards to be met.
Many physicochemical methods have been developed for the
removal of heavy metals from aqueous solutions, such as extraction,
ion exchange, chemical precipitation and membrane separation
processes. These methods have several disadvantages like high
operating costs, low selectivity, incomplete removal, and production
of large quantities of wastes. Conventional methods are limited by
technical and economical barriers, especially when concentration of
metals in the wastewater is low (under 100 ppm). Development of
efficient and low-cost separation processes is therefore of utmost
importance.