Activated Carbon Adsorption of Chromium

Narayana and Krishnaiah and Kannan and Vanangamudi used activated carbon, lignite coal, and bituminous coal for the adsorptive removal of Cr(Vl) ions from aqueous solutions at different pH values of the solution and observed that both adsorption and reduction of Cr(VI) takes place. The adsorption of CrfVl) was maximum at pH = 3 the reduction was maximum at pH = 1. Ouki and Newfeld used a column adsorption technique for the removal of CrfVl) from aqueous solutions in the concentration range 250 to 300 mg/L and observed that the adsorption of Cr(VI) increased significantly in the range of acidic pH values. These workers also observed that at acidic pH values, a radox reaction occurred on the carbon surface active sites when CrfVI) was reduced to Crflll). These active sites were in turn oxidized, resulting in an increased adsorption capacity. 

Lalvani et al. compared the adsorption capacity of CrfVI) and Crflll) from solutions for a commercial activated carbon with a carbon adsorbent produced in the 

At lower concentrations of potassium dichromate, the reaction occurred through the first stage only because the amount of Cr203 formed was found to be almost exactly equivalent to that of potassium dichromate in the solution (Table 6.6). However, as 

Concentration of 100 ml of Solution Mixed KjCrjO, Reduced CrjOj Obtained 

Source Puri, B.R. and Satija, B.R., J. Indian Chem. Soc., 45, 298, 1968. With permission. 

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