A Preparation of Activated Carbon from Macadamia Shell by Microwave Irradiation Activation

Activated carbon was prepared by Macadamia carbonaceous material with different activation condition. The macadamia shell was collected from agricultural waste of Doi Tung, Chiang Rai, located in the northern of Thailand, and then changed into carbon structure by confine space process at 500 degrees C for 1 h. The production yield of obtained macadamia carbon exhibited the yield produce of 31.9% from the initial moisture content of 12.3%. Prior to activation process, carbon was crushed and sieved until the particle size was in the range of less than 2 mm. In general, both physical and chemical activation process requires lots of time. Therefore, in this study, microwave irradiation at different power (90 and 360 watts) and irradiation time (1 to 5 minutes) was investigated in order to reduce the activation time. The carbon was activated by water or ZnCl2 combined with microwave irradiation. Regardless of the activated conditions used, the results showed that the moisture content were less than 5%. The adsorptive capacity of activated carbon was measured by iodine adsorption. For microwave power input of 90 watts, the average iodine adsorption values of 680.8 and 672.4 mg/g were obtained from water and ZnCl2 activation process, respectively. For microwave power input of 360 watts, the average iodine adsorption from water activation showed similar value (678.7 mg/g) whereas average iodine adsorption from ZnCl2 activation increased by 5% (716.3 mg/g). The values obtained from both microwave power conditions of activation process were clearly meet the standard value of Thai industrial No. 900-2547. From this results, it could be activated the carbon within 1 min by microwave irradiation. Finally, the microwave irradiation could be applied to activation process. (C) 2015 The Authors. Published by Elsevier Ltd.