Effects of structural and surface energetic heterogeneity properties of novel corn grain-based activated carbons on dye adsorption

Activated carbons (R-1/2, R-1/3 and R-1/4) were prepared from a novel corn grain precursor by varying the ratio between the carbonized corn grain char and chemical activating agent. The surface characteristics of corn grain-based activated carbons (CG-ACs) were analyzed by nitrogen adsorption isotherms, adsorption energy distributions (AEDs) and X-ray photoelectron spectroscopy (XPS) to evaluate their structural properties, energetic heterogeneities and surface functional groups, respectively. In addition, methylene blue (MB) and congo red (CR) adsorption capacities of highly porous CG-ACs were also examined. It was found that the physical properties and the liquid phase adsorption capacities of CG-ACs increase with ratio between the carbonized corn grain char and chemical activating agent. The results also indicated the higher MB adsorption capacities of CG-ACs compared to that of CR adsorption. The AED results for N2, MB and CR on CG-ACs confirmed the energetically heterogeneous solid surface nature of CG-ACs as well as the decrease in adsorption capacity with increasing energetically heterogeneous solid surface.