Removal of Mercury (II) ions from aqueous solution by adsorption on Cicer arientinum husk: Equilibrium, Kinetic and Mechanism Studies

In the present work, Bengal gram husk (BGH) of low cost, minimally pretreated and locally available abundant agricultural waste material was used as an adsorbent for removal of Hg2+ from aqueous media. The influence of several parameters like effect of pH, adsorbent dosage, initial metal concentration, contact time and presence of interfering ions were studied through batch adsorption studies. The adsorption models of Langmuir and Freundlich were used for for the calculation of isotherm constants. According to the Langmuir model, the maximum adsorption capacity of BGH for Hg (II) ions was found to be 51.85 mg/g. The presence of interfering ions like Mg, Ca, K and Na did not play a role in the removal of Hg (II) ions. The Hg (II) removal by BGH followed pseudo first order rate kinetics. The FTIR spectra and CHN analysis of BGH showed the presence of CH and CO groups on the surface of BGH, which played a significant role in removal of Hg (II). Desorption studies revealed that about 83% of the dye was desorbed at pH 2. The present work showed that the BGH can be applied to remove Hg (II) from wastewater.