Investigation of coal chemical activation compared with physical activation

The usage of activated carbon as an efficient adsorbent is gradually in different separately processesof material and environmental application. Coal is one of the suitable raw material to produce activecarbon (AC) with different properties. In this study, sub-bituminous coal extracted from Abnil mine inZarand region are used to make Ac. It was prepared by chemical activation with zinc chloride andpotassium hydroxide and also by physical activation with carbon dioxide and steam. The activationprocess was carried out in a horizontal reactor at various activation temperatures in the 400–1000°Crange, different dwell times and impregnation ratio of 50%, 100% and 150%. According to weight losspercentages and iodine numbers of AC, the effect of preparation parameters such as carbonization andactivation temperature, dwell time, chemical agents and their impregnation ratio were evaluated. Itappears that in carbonization, chemically and physically activation of coal iodine number and weightloss will be rise by increasing dwell time at constant temperature and by temperature enhancement atconstant dwell time. In both cases, after a certain time and temperature it rise constantly and sometimesmay be decreased.The results show that steam atmosphere was better than carbon dioxide in physical activation and zincchloride had well behavior than potassium hydroxide in chemical activation. In compared withphysically activation, chemically activation of char had better results on surface area and poredevelopment. At final activation temperature of 600 °C and impregnation ratio of 50% were found to besuitable for producing high surface area chemically activated carbon which iodine number wereachieved as high as 813.78. Also the iodine number of AC was 778.32 by physically activation at 1000°Cand weight loss of 45.4% on steam atmosphere.

کلیدواژه ها:

sub-bituminous coal ، Zarand Abnil mine ، active carbon ، carbonization ، physical activation ، chemical activation ، iodine number