Optimized Removal of Cr (VI) and Ni (II) From Wastewater Using Corncob-Derived Activated Carbon

Abstract This research explores the potential of activated carbon (AC), produced from corncobs, for eliminating dissolved hexavalent chromium and divalent nickel. SEM analysis revealed a rough, textured surface on the corncob-derived activated carbon with well-defined pores and crevices, indicating the successful formation of activated carbon. We employed X-ray diffraction to confirm the presence of crystalline graphite within the carbon structure, suggesting effective alignment of carbon atoms. Utilizing Design of Experiments (DOE), we optimized adsorption conditions for enhanced removal efficiency. Our findings reveal that under optimized conditions, the activated carbon achieved a maximum removal of 99.2% for Chromium (VI) at 105 min, pH 2, temperature of 37°C, an initial chromium concentration of 37.2 ppm, and an AC dosage of 0.289 g. Similarly, Nickel (II) removal reached 98.7% at pH 12, temperature of 40°C, a starting concentration of 31 ppm, and an adsorbent amount of 0.94 g. The adsorption kinetics of both metals followed a pseudo-second-order mechanism, suggesting chemisorption as the controlling mechanism. The adsorption data was best described by the Langmuir isotherm, indicating a monolayer coverage of metal ions on the adsorbent surface. These results demonstrate the potential of corncob-derived AC as a promising waste material for removing heavy metal from wastewater.