Preparation of activated carbons from oil-palm-stone chars by microwave-induced carbon dioxide activation

A novel method of preparing activated carbons from oil-palm-stone chars by microwave-induced CO2 reaction was studied in this paper. The effects of processing parameters (gas flow rate, input microwave power and exposure time to microwave energy) and the presence of CuO receptors on the characteristics of the activated carbons were investigated in order to determine and optimise the control parameters for the process. Experimental results showed that it was feasible to prepare activated carbons with high density and predominant microporosity from oil-palm-stone chars by microwave heating. These activated carbons are to be used as gas-phase adsorbents or carbon molecular sieves after a further modification of carbon deposition. CO2 gas flow rate, input microwave power and exposure time were found to be important processing parameters that would significantly affect the quality of the final products. Adding CuO receptors to the char samples increased the surface temperature and significantly reduced the processing time. However, these receptors caused an external heating that resulted in heterogeneous pore structures as shown by the scanning electron microscope micrographs. (C) 2000 Elsevier Science Ltd. All rights reserved.