Characterization of Activated Carbon Prepared from a Single Cultivar of Jordanian Olive Stones by Chemical and Physicochemical Techniques

The yearly production of olives in Jordan is more than 100 kton of which a significant proportion is de-stoned prior to sale. In this work, olive stones from Jordan were used for the preparation of activated carbon with the aim of producing a water treatment product suitable for treatment of contaminated groundwater. The preparation conditions were varied to study their effects on the surface area, porosity, morphology, functionality and crystal structure. Variables studied included time of carbonization, time of activation, activating agent, particle size, sample pre-drying, hydrogen peroxide post treatment and the effect of the activation process itself. X-ray diffraction analysis showed that the prepared activated carbon is essentially amorphous and indicated the presence of traces of oxides of calcium and magnesium, while infrared spectroscopy showed peaks relating to hydroxyl, aliphatic, ether, aromatic and phenolic groups. These functional groups and crystals may have some effect(s), i.e. catalytic, if the products were to be used in any reaction for water treatment. Nitrogen adsorption was used for the determination of apparent surface area and pore size distribution. Results showed that the active carbon is of moderate surface area and micropore volume is over 80% of the total pore volume. Scanning electron microscopy showed the development of the pores during different treatments. The most noticeable effect on the texture was that when the sample was not pre-dried. The adsorption capacity and surface acidity/basicity of all the samples have been studied by methylene blue (MB) adsorption method and partial Boehm titrations, respectively. Results showed that the surface is mainly of basic nature, and also indicated that MB was adsorbed following the pore filling mechanism. Hydrogen peroxide post-treatment produced reduced surface area measurements.