Adsorption of Heavy Metal Ions: Role of Chitosan and Cellulose for Water Treatment

Rapid industrialization and modernization have introduced substantial amounts of toxic heavy metals into the aquatic and terrestrial environment which possess a serious threat to the flora and fauna. In recent years, considerable research work has been done and is currently underway on a number of natural biopolymers and their modifications to remove different kinds of heavy metal ions. Chitosan and cellulose, both naturally occurring polysaccharides are the most effective adsorbents for the removal of heavy metal ions from waste water. This review is aimed to provide relevant and recent information on the application of chitosan, cellulose and their respective derivatives for the removal of toxic heavy metal ions. INTRODUCTION: Majority of industries and mainly the mining operations, tanneries and metal plating play a vital role in contaminating the environment with heavy metals 1 . Heavy metals particularly mercury (Hg), chromium (Cr), lead (Pb) and cadmium (Cd) have lethal effects on all forms of life even at low concentrations. Various methods including chemical precipitation 2 , nano filtration 3 , solvent extraction 4 , ion exchange 5 , reverse osmosis 6 and adsorption 7 have been extensively studied in recent decade to decontaminate the polluted waters. Out of all these methods, adsorption is particularly attracting scientific focus mainly because of its high efficiency, low cost, easy handling and high availability of different adsorbents. QUICK RESPONSE CODE DOI: 10.13040/IJPSR.0975-8232.IJP.2(6).280-89 Article can be accessed online on: www.ijpjournal.com DOI link: http://dx.doi.org/10.13040/IJPSR.0975-8232.IJP.2(6).280-89 Over the past few years, several research studies have been conducted globally on natural polymers and various methods have also been developed to enhance their metal binding 8 properties. Adsorption process is known to depend upon various experimental conditions such as particle size, pH, metal concentration, ligand concentration and competing ions 9 .Scientists have focused their momentum for the search of low cost and easy available biomaterials for the waste water treatment. Chitosan 10 , alginate 11 , cellulose 12 and lignin 13 are some of the well known natural polymers that have received considerable attention for water treatment. Characteristics of various types of biopolymers are shown in (Table 1). A vast literature is nowadays available on all of these biopolymers. In view of their excellent properties to be used as efficient materials for heavy metal adsorption this review will highlight some of the recent studies conducted on chitosan and cellulose for water treatment. In addition this review will focus on various derivatives of these polymers that have been developed to enhance their efficiency in removal of toxic and heavy metals.