The Effect of Pre-washing Process with NaOH Solution on the Surface Area in Activated Carbon Production

Abstract

The alkaline pre-washing process in the production of activated carbon is an important step and a factor that affects the characteristics of activated carbon. Alkaline pre-washing is used to optimize the surface properties of activated carbon, increase its adsorption capacity, and remove unwanted substances.
 
 In this study, hazelnut shells were selected as the raw material for producing activated carbon. ZnCl2 was used for chemical activation, and physical activation was carried out at 650 °C. However, prior to the chemical activation process, a pre-washing process with NaOH solution was applied to remove acidic groups present in the raw material. The structural properties of the activated carbon obtained from samples subjected to the pre-washing process and those without the pre-washing process were determined using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) for surface morphology, Brunauer-Emmet-Teller (BET) for pore size analysis, and Thermogravimetric Analysis (TGA) for temperature-dependent mass loss.
 
 The surface area of the activated carbon produced without pre-washing with NaOH solution was found to be 770 m²/g, with a carbon content of 87.10% by weight. After the pre-washing process with NaOH solution and subsequent chemical and physical activation, the surface area of the activated carbon increased to 1935 m²/g, with a carbon content of 95.51% by weight. Therefore, subjecting the raw material to the pre-washing process with NaOH solution not only increased the carbon content but also increased the surface area value by approximately 2.5 times.