Removal of cadmium from wastewaters with low-cost adsorbents

Instead of using commercial activated carbon or ion exchange resins, researchers have worked on inexpensive materials, such as wastes from industry and agricultural operations due to their outstanding adsorption behavior toward heavy metal ions. Low-cost adsorbents are easily and locally available in large quantities. The modification of these materials could considerably increase their sorption capacity. In this review, the technical feasibility of various low-cost adsorbents for removal of Cd(II) from wastewaters has been discussed. Due to widespread cadmium contamination and its toxicity, there is considerable interest to remove it before discharge into wastewater streams. Several factors affecting an adsorption process such as pH, contact time as well as the reported maximum adsorption capacity values are summarized. The subsequent regeneration and reuse of adsorbents has been given considerable attention and some adsorption studies using real wastewater samples were also discussed.