Application of Response Surface Methodology in Phenol Red Adsorption Using Kola Nut (Cola acuminata) Shell Activated Carbon

Abstract

The application of response surface methodology in phenol red adsorption using kola nut shell activated carbon was studied. Chemical method of activation using zinc chloride (ZnCl2) was used to prepare the carbon. The impregnated samples were kept in an oven at 383K for 24 hours. The dried samples were carbonized in muffle furnace for 1 hour at 773K. Some physical properties of the carbons such as surface area, pH, moisture content, ash content, bulk density were determined. Both the activated and non-activated carbons were characterized using the Fourier Transform Infrared (FTIR) spectroscopy to determine the functional groups and Scanning Electron Microscopy (SEM) to examine the surface morphology of the carbon. Preliminary adsorption studies were carried out to determine the significance of the parameters in adsorption process. The parameters shown to be more significant were adsorbent dosage and initial ion concentration.  The adsorption process was optimized using the Central Composite Design (CCD) for three factors and the optimization results were analyzed using Design Expert 8.7.0.1 trial version.  The optimum conditions for the adsorption of the dye were 303K, 60 minutes, 0.30g of adsorbent, initial ion concentration of 300 mg/l and pH 10 which resulted in 89.95% removal of phenol red. Quadratic polynomial model was developed by the Design Expert used for the process parametric study to achieve optimal performance. The model predicted was in close agreement with the experimental result confirming the suitability of the proposed quadratic model.  The study showed that CCD can conveniently be used for the optimization of phenol red adsorption using kola nut shell activated carbon.