Chapter 4 - Low-cost adsorbents, removal techniques, and heavy metal removal efficiency

Abstract

Gradual acceleration of heavy metal contamination in the aquatic environment experienced an enormous concern in the second half of 20th century, as the existence of many industrial and environmental accidents warned the world for the sake of detrimental environmental consequences. Water pollution caused by heavy metal concentration, along with their associated toxic effects resulting from several industrial activities, is a serious threat to the environment and human health and is a matter of worldwide concern. Effluents from enormous number of industries such as electroplating, leather, tannery, textile, pigment and dyes, paint, wood processing, petroleum refining, and photographic film production encompass a significant quantity of heavy metals in their wastewater. The conventional techniques for the treatment of heavy metal contamination consist of chemical precipitation, solvent extraction, chemical oxidation, ion exchange, membrane separation, reverse osmosis, electro dialysis, etc. However, the several disadvantages linked with these methods, such as higher cost, being energy intensive, and often related with the generation of toxic by-products, made them unpopular. Thus the adsorption process has been explored as one of the cost-effective techniques, along with its greater removal efficiency for heavy metal ion concentration from wastewater. The objective of this chapter is to emphasize the numerous low-cost adsorbents such as locally available natural materials, various agricultural wastes, and their indigenous preparation toward the effective adsorbent and greater removal efficiency for the removal of heavy metal contamination in wastewater. This chapter highlights this alternative low-cost adsorbent abundantly present in nature as a potential component for the removal of toxic heavy metals from industrial effluent and the adsorption process involved.