Studies on chromium removal by rice husk carbon

The activated carbon prepared by carbonisation of rice husk with sulphuric acid followed by CO2 activation showed 88% removal of total chromium and greater than 99% removal of hexavalent chromium. As with commercial carbon, the removal was maximum at a minimum proton to chromium ratio of 5.0 and chromium to carbon ratio of 0.0065. The above ratios were found to be valid over a wide range of Cr (VI) concentrations. The Freundlich adsorption plots gave identical slope values indicating similar type of adsorption mechanism are involved for the removal by both carbons. Coloumn studies showed capacity of 8.9 mg/g and 6.3 mg/g for rice husk and commercialc arbons respectively, for Cr (VI) removal. The average percentage of Cr (VI) recovery was found to be 22.5% and 30.6% respectively when alkali followed by acid were used for regeneration. The developed carbon was used to remove Cr (VI) from the waste waters of a chromium plating shop.