3.1 Cation Exchange Capacity of Biochar Materials

The value of CEC was measured for the biochar materials made from the pelletized peanut hulls at pyrolysis temperature of 371, 402, 426, and 442°C. As shown in Fig. 3, the measurements demonstrated that the CEC value of the biochar materials is dependent on the pyrolysis temperature. Pyrolysis temperature of 402°C yielded the highest CEC value (18.2 meq/100 g) while the pyrolysis temperatures of 371, 426, and 442°C resulted in CEC values of 17.1, 16.1, and 13.9 meq/100 g, respec­tively. This experimental result indicated that it is important to control pyrolysis temperature for higher CEC value of biochar product. The optimal pyrolysis tem­perature for high-CEC biochar production is likely at around 400°C.