Dear Baraa Anaya,

if you are aiming for adsorption of CO2. Applying a high pressure, which is slightly lower than the respective saturation point, allows you to adsorb as much as possible on the surface of your probe material. Applying pressures beyond the saturation point would switch the problem to an adsorption out of the liquid phase. Positive would be that you can store as much as is possible for your respective probe material, a negative effect is that your apparatus has to withstand such high pressures and that you need compressed gas at this pressure or higher.

If you are aiming for absorption or a chemical reaction, increasing the partial pressure of one reaction component increases according to the principle of LeChatelier Braun the will of the component to react and influences the equilibrium of your chemical reaction.

Hi Baraa

Near room temperature, CO2 is near super critical point. The phase diagram near that condition is too much sensitive to any temperature noise. This is the major drawback. Pressure reading and adsorption reading become too noisy. Large quantities of sample as well as temperature control is required for accurate reading at that condition. Here Sieverts vs. differential reading become more meaningful. With differential readings it is possible to remove noises to high extends.

Ali