Evaluating the Experimental Uncertainty in Gas and Vapor Sorption/Adsorption Measurements: Fundamental Considerations and Experimental Design Implications

High-quality, accurate, and reliable sorption and adsorption data provide the basis for designing large-scale, energy-efficient membrane/adsorption processes for gas and liquid separations and evaluating their techno-economic feasibility . As highlighted by Prof. David Sholl during his plenary lecture at the 2020 NAMS (North American Membrane Society) conference, the lack of uncertainty associated with published sorption/adsorption data represents one of the major roadblocks to progress in separation technologies. In this study, a standard methodology to estimate the uncertainty associated with sorption/adsorption measurements is proposed. A systematic analysis of the experimental uncertainty of gas and vapor sorption/adsorption measurement in polymers using the barometric method is performed in a variety of operative conditions, to individuate which factors contribute the most to the overall uncertainty under different experimental operation modes. This effort should push researchers in the field to adopt a standardized method to estimate the experimental uncertainty, which is expected to make experimental data coming from different laboratories in the world easier to compare. Finally, the validity of the linear error propagation method, generally used to evaluate the uncertainty of sorption/ adsorption data, is demonstrated by a vis-a-vis comparison with the Monte Carlo statistical method. Fundamental aspects and practical implications are highlighted and discussed.