The effects of demineralization and swelling in producing active carbon from Turkish lignites

In this study, active carbon was obtained through chemical activation methods using some pretreatment to Gölbaşı (Adıyaman) and Kangal (Sivas) lignites. For both lignites, pretreatment was carried out in three steps. In the first step, demineralization was achieved by applying HCl–HF pretreatment to raw lignites. In the second one, raw and demineralized lignites were swollen not only with benzene but also with THF (tetrahydrofurane). Later, these two samples at 85 °C were exposed to chemical activation by impregnation with ZnCl2. Chemical activation processes were carried out in a situation where samples on quartz board in a quartz tube in a cylindrical furnace were kept for 1 h at 500 °C, 100 ml/min N2 flow speed and 30 °C/min heating rate. The active carbons produced were washed with 10% HCl and later with demineralized water. BET surface area of the active carbon samples was generally higher than 1000 m2/g. The surface area value of the Gölbaşı lignite was relatively higher than that of Kangal lignites. Similarly, the surface area value of the active carbons produced at the end of pretreatment with THF was higher than that of active carbon produced through pre-swelling using benzene. For all active carbon samples, ash, total sulfur and iodine adsorption values were different.