What are the different types of experimental methods to measure CO2 adsorption on solid sorbents, in particular? What are uncertainties of data and pros and cons of all measurement methods?
I refered a good number of journal articles and books. I feel the information is available in bits and pieces. Though the book "GAS ADSORPTION EQUILIBRIA;Experimental Methods and Adsorptive Isotherms" by Jürgen U. Keller and Reiner Staudt proved to be useful in general, I am particularely looking for CO2 adsorption measurement techniques that are in practice on laboratory scale for the assessment of adsorbent performance. I look forward to replies/comments/suggestions for further reading.
In our laboratory we use both gravimetric and volumetric measurements for adsorption of carbon dioxide on solid sorbents. we carry out volumetric methods in Micromeritics surface area and porosity analyser which gives results in cm^3/g.STP. The isotherms can however only be measured up to 1 bar and one requires a good external thermostat which could maintain the constant temperature around the sample. For Gravimetric measurements we have Hiden-IGA-001 which can measure isotherms of any gas up to 20 bar pressure and 500C temperature. The instrument is fully automatic has options for in situ activation of samples and very sensitive can measure uptake in milligrams up to 5 places of decimal. The instrument can apply bouncy corrections automatically while reporting uptake in wt% or mmol/g but care has to be taken to enter the correct skeltal density of the loaded sample in buoncy setup of instrument. we determine skeltal density of our samples by helium pycnometry. For still higher pressures up to 150 bar we have rubotherm magnetic suspension balance which also has high accuracy for isotherm measurements. we have and earlier version of instrument which however can't apply buoncy corrections automatically and data has to be processed further manually for applying these corrections. I don't know of any instrument which can measure volume/volume capacity directly. The gravimetric and volumetric measurements when converted to volume/volume measurements give different results depending on weather we are using bulk , sketal , particle, or crystallographic specific volume of adsorbent. It is thus always advisable to report which volume has been used in volume/volume calculations. you can further see our publications in this regard on my profile page
I agree with the previous answer. You can measure CO2 sorption processes using different, thermal, gravimetric and volumetric techniquies, where each technique can give different information.
We use TGA, DTA and TPX, as well as low and high pressure volumetric techniques.
Thank you all for helpful comments. Could the relatively novel methods such as Oscillometry and Impedance spectroscopy also be employed for present purpose? Do they score over Volumetry/manometry and Gravimetry in terms of more measurable parameters?
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