Environmental Engineering Reference
In-Depth Information
environmental scientists and engineers to look beyond traditional materials and explore
new treatment methodologies that incorporate nanoparticles of high reactivity,
selectivity and versatility. With these new adsorbents, perhaps more small-scale and
household-based heavy metal removal systems could be installed, at a fraction of the
current cost, especially in areas without central treatment infrastructures (e.g., in
Bangladesh where groundwater pollution by geogenic arsenic is common) (Smedley and
Kinnburgh, 2002). Emerging iron-based and polymeric materials engineered by
nanotechnology with promising heavy metal removal capability therefore attracts great
interests. This chapter gives a brief overview on the two main types of nanoparticles for
adsorptive removal of heavy metal ions: iron-based nanoparticles and polymeric
nanoparticles.
For readers who are interested in utilization of nanoparticles in analytical
separation such as their uses as stationary phases in capillary electrochromatography are
directed to that of Guihen and Glennon (2003). Comprehensive reviews on carbon-based
nanoparticles and zero-valent iron nanoparticles for environmental remediation have
already been made by Yue and Economy (2005) and Li et al . (2006) respectively.
Savage and Diallo (2005) have also briefly reviewed the application of nanoscale
catalysts and adsorbents in water purification for mitigation of both organic and
inorganic pollutants. However, there is rarely any overview focusing on nanoparticles or
nanoparticle-based adsorption technology for mitigation of heavy metal pollution, in
spite of the tremendous progress in the area being achieved in recent years.
6.2
Iron-Based Nanoparticles for Removal of Heavy Metal Ions
6.2.1 Introduction
Over the past decades, extensive synthetic efforts from chemists and process
engineers have led to discovery of many novel metal and metal oxide nanoparticles
(Rotello, 2004). Many of them display unprecedented properties. For instance, Haruta
(1997) reported that gold nanoparticles of ~10 nm could catalyze carbon monoxide
oxidation at low temperature, whereas gold in bulk is not catalytically active at all.
However, current efforts in application of metal and metal oxide nanoparticles for
water/wastewater decontamination such as heavy metal removal have focused almost
solely on iron-based nanoparticles or their subcolloidal particles.
Iron nanoparticles are made usually in the size range of 1100 nm, and are
highly reactive because of their large specific surface areas. Iron-based nanoparticles are
inexpensive, easily scalable and highly reactive towards a wide array of organic and
inorganic pollutants (Zhang, 2003). Being the most widely utilized nanoscale remedial
agents, iron-based nanoparticles have been extensively studied in their synthesis
 
 
 
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