Document Abstract
Environmental pollution, particularly from heavy metal ions in the
wastewater, is one of the most serious concerns of the world. In the
pursuit of remedial action, various conventional methods such as
ion exchange, chemical precipitation, coagulation, membrane
separation, reverse osmosis, and adsorption methods have so far
been used for the removal of heavy metal ions. A good variety of
adsorbents have been developed to remove different heavy metal
ions from wastewater in particular those which have been detrimental to living organisms. Adsorption processes have been very
demanding for high removal efficiency of heavy metal ions even at
trace levels and they are low cost as compared to conventional
methods. It has therefore been crucial to develop low cost and
readily available adsorbents for the adsorption of heavy metal
ions from wastewater. The adsorbents may be collected from agricultural and animal waste and industrial by-products. All adsorbents, by their intrinsic nature, have functional groups to play the
key role in metal ion adsorption. Generally, chemically modified
adsorbents enhance the surface area of the adsorbent and exhibit
higher adsorption capacity than unmodified adsorbents. In this
review, a series of natural waste materials and their modified
forms have been evaluated for the removal of various metals from
potable and wastewater. The major focus has been an accumulation of comprehensive knowledge on of the use of the low-cost
adsorbents for removal of heavy metal ions.