Batch and column studies for the adsorption of chromium(VI) on low-cost Hibiscus Cannabinus kenaf, a green adsorbent

Adsorption is one of the excellent ways for heavy metal removal from aqueous solution because of advantages like the low cost, availability, profitability, ease of operation and efficiency. In this study, adsorption potential of a low cost adsorbent Hibiscus Cannabinus kenaf was investigated for Cr(VI) removal from water using batch and continuous mode experiments. Optimum removal of Cr(VI) ions was occurred at pH 7. The kinetic results showed that the Cr(VI) removal followed intraparticle diffusion kinetics with a correlation coefficient greater than 0.94. The adsorption isotherms of Cr(VI) could be described very well by both the Langmuir and Freundlich equations (R-2=0.997). The maximum Cr(VI) uptake was found to be 582 mu g/g in Langmuir model. Column studies have been carried out to compare these with batch capacities. The Yoon-Nelson and Thomas models were found appropriate for description of the breakthrough curve, whereas the Bohart-Adams model was not match very well. The recovery of Cr(VI) and chemical regeneration of the spent kenaf have also been studied. The high Cr(VI) adsorption capacity and regeneration efficiency of kenaf suggests it as a promising alternative for heavy metal removal specially at near circumneutral pH. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.