Indeed, it is acceptable for functionalized and unfunctionalized Zr-based MOFs to exhibit distinct isotherms, as functionalization induces surface heterogeneity that might alter adsorption behavior, transitioning from Langmuir to Freundlich models.

It is OK, but more data are required to help you because is it valid, but the gas polar or no-polar must be considered with changes.

Thank you very much, Sir Rafael Vargas-Bernal . My adsorption is not about gas but on aqueous solution. Still, thanks sir for your insights.