Properties of activated carbon prepared from coconut shells in Ghana

Abstract

Activated carbons have applications in various industrial processes in Ghana including purification of water and gold adsorption from gold solutions. Materials commonly used for the preparation of activated carbons include coal and coconut shells. Ghana generates significant quantities of coconut shells from coconut oil processing activities but apart from a small percentage of the shells, which is burned as fuel, the remaining is usually dumped as waste. To increase recycling and utilisation of the coconut shells, activated carbons were prepared from the shells by carbonisation of the shells at 900oC in an inert atmosphere of nitrogen, followed by steam activation of the resulting char also at 900oC activation temperature and various durations of activation. The adsorptive properties determined for the resulting Coconut Shell Activated Carbons (CSAC) fell within the values of the reference commercial activated carbon (Norit RO 3515) commonly used by most Ghanaian mining companies. For example, the specific surface area of the CSAC reached a maximum value of 795 m2/g after 3.5 hours of activation: well within the range of 780-812 m2/g obtained for Norit RO 3515. Also, the maximum total pore and micropore volumes developed in the CSAC were 0.42 cm3/g and 0.38 cm3/g respectively compared to 0.44 and 0.39 for the Norit RO 3515.