v i is the diffusion volume based on the group contribution method, C is an arbitrary constant, b is the exponent dependency of temperature, and α 1 , α 2 are the diffusion volumes' exponents. All parameters were identified by solving an estimation problem. In such work, C, b, α 1 , α 2 were found to be 1 × 10 -8 , 1.75, 1/3, 1/3, respectively for T in K, P in atm, M i in g/mol, D i,j in cm 2 /s. The Diffusion Volumes can be found in work.