Synthesis of activated carbon from Balanites aegyptiaca and hyphaene thebaica shells by physical activation

Abstract

Activated carbon is a porous material that has several applications, including in the fields of adsorption and catalysis. This material can be obtained from any lignocellulosic biomass. The aim of this work is to synthesize activated carbon (AC) from Balanites aegyptiaca (BA) and Hyphaene thebaica (HT) shells. The material is obtained after physical activation under nitrogen or carbon dioxide flow. The characterization of the material has been carried out using a variety of analytical methods, including nitrogen adsorption at 77 K to determine its porosity and specific surface area, the iodine index and methylene blue index tests. Surface functions, pH to point of zero charge measurement to determine its acidity, and X-ray diffraction to examine its structural properties. The most optimal values for specific surface area and porous volume are 939 m²/g and 0.572 cm³/g, respectively, for Balanites aegyptiaca. For Hyphaene thebaica, they are 1329 m²/g and 0.589 cm³/g. It is noteworthy that 62 % of the samples have mean pore diameters higher than 20 Å. The results of the iodine and methylene blue index tests show that the samples have a satisfactory adsorption capacity within the aqueous phase. The surface functions of the activated carbons prepared are basic, with pH values ranging from 10.2 to 10.8 at the point of zero charge. The structure of these materials is amorphous, with fine graphitic zones.