This study investigates the separation based on adsorption of the binary gas mixture of hydrogen withbiogas (gases: CO2, CH4, O2, N2) and inert gases (gases: He, Ne, and Ar) using single-walled ((7,7), (15,15),(29,29), (44,44), (58,58) and (73,73) SWBNNTs), double-walled ((11,11)@(15,15), (7,7)@(22,22) DWBNNTs)and triple walled ((8,8)@(11,11)@(15,15) and (7,7)@(15,15)@(22,22) TWBNNTs) boron nitridenanotubes via the grand canonical Monte Carlo (GCMC) simulation. Two models, namely, spherical andsite-site models, are employed for gas. Two conditions are used for the SWBNNTs, i.e., SWBNNTs withatomic charges and SWBNNTs without atomic charges. This paper also examines the impact of nanotubediameters on binary mixture adsorption. The results indicate that considering the H2/gas separation inthe studied BNNTs, the H2 separation from He and the H2 separation from Ar have the maximum andminimum selectivity values, respectively. Also, with increasing pressure and temperature, the values ofthe H2/He selectivity in the studied BNNTs decrease. Manuscript profile