Preparation of activated carbon from corn cob and its adsorption behavior on Cr(VI) removal

Operation experiments were conducted to optimize the preparation of activated carbons from corn cob. The Cr(VI) adsorption capacity of the produced activated carbons was also evaluated. The impact of the adsorbent dosage, contact time, initial solution pH and temperature was studied. The results showed that the produced corn cob activated carbon had a good Cr(VI) adsorptive capacity; the theoretical maximum adsorption was 34.48 mg g⁻¹ at 298 K. The Brunauer–Emmett–Teller and iodine adsorption value of the produced activated carbon could be 924.9 m² g⁻¹ and 1,188 mg g⁻¹, respectively. Under the initial Cr(VI) concentration of 10 mg L⁻¹ and the original solution pH of 5.8, an adsorption equilibrium was reached after 4 h, and Cr(VI) removal rate was from 78.9 to 100% with an adsorbent's dosage increased from 0.5 to 0.7 g L⁻¹. The kinetics and equilibrium data agreed well with the pseudo-second-order kinetics model and the Langmuir isotherm model. The equilibrium adsorption capacity improved with the increment of the temperature.