A Study on Lead and Chromium Adsorption Using Carbon Nanomaterials

Rapid development of industries in the world has been the major contributor to pollution of water resources such as heavy metals. These heavy metals are very hazardous to both human and environment since they do not degrade into harmless end product but they eventually will be accumulated in living organisms and thus causing various illnesses and syndromes. Many methods have been researched in order to remove these dangerous heavy metals and one of the best methods is adsorption. Present study was undertaken to investigate ability of carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as adsorbents in adsorption process of removing lead and chromium ions from aqueous solutions. The analyses of metal ions removal were performed on four operation parameters which were initial ion concentration, contact time, pH and temperature. The experiments were carried out using a bath shaker at constant speed of 200 rpm. BET surface area of CNFs was found to be 194.99 m2/g, while for CNTs, the BET surface area was found to be to be 478.99 m2/g. Batch adsorption test showed that adsorption of lead and chromium uptake increase as the contact time increases till equilibrium. Besides, it was found that higher initial metal concentration resulted to better adsorption uptake till it reached its limit as the adsorbate per adsorbent ratio increased. Adsorption is optimum from pH 5 -9 for chromium, while for lead, pH 6 and pH 9 are considered as optimum pH. Increased in temperature will slightly promote desorption of lead, however, it does not affect much on chromium adsorption. The equilibrium data fitted to Langmuir isotherm better for both metals in comparison with Freundlich isotherm, indicating that the adsorption processes are monolayer.