The application of low-cost adsorbents obtained from plant wastes as a replacement for costly conventional methods of removing
heavy metal ions from wastewater has been reviewed. It is well known that cellulosic waste materials can be obtained and employed
as cheap adsorbents and their performance to remove heavy metal ions can be affected upon chemical treatment. In general, chemically
modified plant wastes exhibit higher adsorption capacities than unmodified forms. Numerous chemicals have been used for modifications
which include mineral and organic acids, bases, oxidizing agent, organic compounds, etc. In this review, an extensive list of plant wastes
as adsorbents including rice husks, spent grain, sawdust, sugarcane bagasse, fruit wastes, weeds and others has been compiled. Some of
the treated adsorbents show good adsorption capacities for Cd, Cu, Pb, Zn and Ni.
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