Here, p is the pressure expressed in Pa, N is the amount absorbed in mol g^-1, T is the temperature in K,a_i and b_j are Virial coefficients, and m , n represent the number of coefficients required to adequately describe the isotherms. The values of the Virial coefficients a₀ througha_m were then used to calculate enthalpies (Q _st) of absorption using (eq. 4)²⁵.