The adsorption behavior of rice husks for antimony ions from aqueous solutions has been investigated by Khalid et al. [93]. The adsorption was studied as a function of appropriate electrolyte, equilibration time, hydrogen ions, amount of adsorbent, concentration of adsorbate, effect of diverse ions and temperature. Quantitative adsorption of antimony from aqueous solutions on rice husks was achieved within a short contact time of 10 min. The reaction was found to be endothermic and occurred in presence of a variety of anions, with maximum adsorption in the presence of 0.01 M HNO3. The same researchers also studied the removal of Pb(II) and Hg(II) using rice husk as an adsorbent [94] and [95].