ADSORPTIVE REMOVAL OF CHROMIUM (VI) FROM ELECTROPLATING WASTEWATER

Abstract

In the present work, hexavalent chromium and COD removal from electroplating wastewater was investigated using a low cost activated carbon, which was carbonized and activated from corncobs. Corncob based activated carbon (CAC) was characterized to understand the adsorption characteristics of chromium (VI) ions on adsorption and its physiochemical properties. The particle size of CAC was in the range of 450-850 μm. Proximate and ultimate analysis of CAC showed the presence of high carbon content. BET surface area and pore volume were found 399.006 m2g-1 and 0.23 cm3g-1 respectively. The effect of parameters such as temperature (T), adsorbent dose (w), pH and contact time (t) on adsorption of chromium ions by CAC was investigated. The pH ≈3.0 is found to be optimum for the removal of Cr(VI) and COD from wastewater by CAC at an optimum dose of 15 Kg/m3. Optimum value of contact time is found as 6 hr. Various isotherm models were fitted for Cr(VI) and COD removal. Freundlich model well fitted to Cr(VI) adsorption while Redlich-Peterson is found to be fit for COD removal. Pseudo-second order kinetic model was well fitted for both Cr(VI) and COD removal. Thermodynamic parameters represent the exothermic and spontaneous nature of adsorption.