Our current filter is a sponge with a surface area of 65 cm³ attached to the drone that is soaked in an aqueous Ammonium Bicarbonate solution. Our testing suggests that the filter is effective in absorbing a nonzero amount of CO².

We used a 3:2:10 ratio of Baking Soda, Ammonia (clear), and water to create our solution of aqueous Ammonium Bicarbonate. We followed this up with our regeneration process to confirm results.

Baking Soda, known as Sodium Bicarbonate, has a chemical formula of NaHCO³ and acts as a base. Ammonia, specifically clear as to avoid any unaccounted for acidity from citrus scents, has a chemical formula of NH³ and is treated as an acid. Water, H²O, is used for the purposes of dilution and solubility. The final component is the Carbon Dioxide or CO².

In a ventilated area, we mixed 2 tbsp of NH³ into 10 tbsp of H²O as to dilute our acid. We then added 3 tbsp of NaHCO³ to safely neutralize the acid. The sponge was then soaked for five minutes. 

Below is the chemical equation for the formation of Ammonium Bicarbonate.

NaHCO³​+NH³​+H²​O→NH⁴HCO³​+NaOH 

Once placed outside the H²O makes the CO² water soluble allowing it to bind to the aqueous NH³ (a common cleaning product that binds well with carbon) effectively capturing the atmospheric CO² and storing it in our sponge. We allowed the sponge to sit outside for 30 minutes. 

Below is the chemical reaction with Carbon Dioxide to form Ammonium Carbonate

2NH⁴​HCO³​+CO²​→(NH⁴​)2​CO³​+H²​O

With pre-seed grant money, we would invest in professional chemistry equipment to make our solution more accurately and consistently. 

We would also change our filter medium to something with a larger surface area that is still absorbent, such as a large fabric.

We anticipate much trial and error in this phase.

In the future we would likely switch to professionally manufactured chemical compounds such as Amine or PEI to greatly improve our filtering capabilities.

We would also transition to optimally shaped filters that do not cause much drag, but still have a high contact time and maximal surface area. Our current favorites are a "wind sock" or "tentacle" design.