One of the questions that has been posed is how is the air traveling through the sample. The assumption in our paper  (https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4148065) is that the CO2 is dissolving in the water to become carbonic acid. And this is happening throughout the sample.

The material is very porous, and here is a video I captured using a clear container to show the micro bubbles which pour from all parts of the sample.