Biochar is the carbonaceous solid byproduct resulting from pyrolysis of any carbonaceous material. It could also simply be referred to as “char,” if the carbonaceous solid is to be employed in applications other than soil amendment or environmental management (Deal et al., 2012). Because of its less well-developed porosity, the adsorption capacity of biochar is still limited. Therefore, to increase its porosity, biochar is activated by either physical or chemical activation methods. During the activation process, the tarry products in the biochar are removed, pore diameters widened, while at the same time, new porosity is created. The result is activated carbon, which is a more highly porous carbonaceous solid byproduct, with a subsequently higher adsorption capacity than biochar.

Thanks for the answer. What Im looking for is if there a minimum surface area for a carbon to be called activated carbon. I have a memory that 600 m2/g is a minimum but cannot find that data. In the same document was as far I remember 4 grades of ACs depending on SSA, carbon content and ash content.