Preparation and characterization of activated carbons from oil-palm stones for gas-phase adsorption

Preparation and characterization of activated carbons from oil-palm stones by carbon dioxide activation were studied in this paper. These oil-palm stones are agricultural by-products from palm-oil mills in several tropical countries. Ultimate and proximate analyses, pycnometry, mercury porosimetry, surface area and porosimetry as well as transmission electron microscopy were carried out for evaluating the textural properties of the activated carbons. It was found that the activation temperature and hold time had significant influences on the surface area and pore size distribution of the activated carbon. The optimum conditions for preparing these activated carbons from chars pyrolyzed at 600°C to derive the highest specific surface areas were found to be an activation temperature of 900°C and a hold time of 30 min. For chemical characterization, an X-ray diffractometer and a Fourier transform infrared (FTIR) spectroscope were used to identify the inorganic components and surface organic functional groups of the activated carbons, respectively. The activation temperature and hold time had significant effects on the surface functional groups. For the determination of the adsorptive capacity of the activated carbons, adsorption of sulphur dioxide was carried out using thermogravimetric analyses. Experimental results showed that sulphur dioxide could be adsorbed effectively by the oil-palm stone-activated carbons. The adsorptive capacity of these activated carbons was comparable with those of some commercial activated carbons.