BULK DENSITY, MICROCRYSTALLITE AND POROSITY OF CARBON PELLET FROM NITRIC ACID TREATED SELF-ADHESIVE CARBON GRAIN FROM OIL PALM EMPTY FRUIT BUNCH

Abstract

Self-adhesive carbon grain (SACG) prepared from oil palm empty fruit bunch (EFB) by a low carbonization process were treated with 1, 3, 5 and 7 Molar (M) nitric acid (HNO3) at 270C and 1000C. The SACG green pellets were converted into carbon pellets by a carbonization process up to 10000C in N2 environment using a multi-step heating profile. The treatment was found to increase the green pellets density from 1.24 gcm-3 to about 1.35gcm-3, but there was no significant change in pellet density after carbonization. X-ray diffraction analysis showed that 1 M treatment at 270C caused the stacking height (Lc) and width (La) of microcrystallites of carbon pellets to increase from 0.866 to 1.339 nm and from 3.534 to 8.720 nm respectively. Above 1 M the microcrystallite dimension of carbon pellets decreased but their values are still higher than that for the untreated samples. A similar trend was observed for the treatment at 1000C. The BET isotherm plots show that the increase in molarity can widen the middle region of the relative pressure that has negative curves, and for molarity higher than 3 M the BET experiment is no longer able to produce such a plot. This results demonstrate that a significant change in the microcrystallite dimension or pore structure in carbon pellets due to the treatment is corresponding to a dramatic change in their adsorption capacity.