Megan Logue

 Is a.1 M or a 1 M solution of sodium hydroxide more effective at extracting and absorbing carbon dioxide from air?  Will carbon dioxide be absorbed more efficiently by sodium hydroxide at 16°C or 32°C?

 The increasing amount of CO 2 in the Earth’s atmosphere has the potential to severely harm the environment and affect society.  The purpose of carbon capture is to remove CO 2 that would otherwise build up in the atmosphere.  One method of carbon capture is the implementation of artificial trees in the environment. ◦ An artificial tree operates by enabling air to filter through its structure and removing the air’s CO 2 with a sorbent material, such as sodium hydroxide, or NaOH.  The initial pH value of a solution of NaOH will decrease as it captures CO 2 from air.  This change in pH can be used to determine the exactly how many molecules of CO 2 are extracted from air over a period of time.

 A solution of NaOH and water can be used to extract CO 2 from air. The reaction between a solution of NaOH and CO 2 is as follows: ◦ CO 2 + H 2 O = H 2 CO 3 ◦ NaOH + H 2 CO 3 = NaHCO 3 + H 2 O ◦ NaHCO 3 + NaOH = Na 2 CO 3 + H 2 O  Overall reaction: ◦ CO NaOH = Na 2 CO 3 + H 2 O  This indicates that for every two moles of NaOH, one mole of CO 2 is extracted from air.

 As the concentration of the NaOH solution increases, the amount of CO 2 absorbed will increase as well.  Also, as the temperature of the system increases, the amount of CO 2 extracted from the air will also increase.

 2 L of 1 M solution of NaOH  mL Erlenmeyer flasks  mL graduated cylinders  2 aquarium pumps  2 stirring rods  Small weights  Water bath  Incubator  2 Vernier pH probes  2 Vernier temperature probes  Logger Pro Date Logger  Computer  Water  Paper towels  Safety gloves  Safety goggles  Safety apron  Calculator  Sink

 A.1 M solution of NaOH and a 1 M solution of NaOH were prepared in separate Erlenmeyer flasks. Both flasks were placed in the water bath set at 20°C.  Separate tubes connected to aquarium pumps, a Vernier temperature probe, and a Vernier pH probe were placed in each flask.  The probes were set to collect samples at increments of 10 minutes over a time period of 24 hours with Logger Pro Data Logger.  After 24 hours, the collected data was recorded. The procedure at 20°C was repeated twice to perform a total of three trials.  Next, an incubator was set at 40°C. The.1 M and 1 M solutions of NaOH were placed in the incubator. An aquarium pump, a Vernier temperature probe, and a Vernier pH probe, were placed in each flask.  Once the temperature of each flask was stable at 40°C, the data collection was promptly started on Logger Pro Data Logger. After 24 hours, the collected data was recorded. The procedure at 40°C was repeated twice to perform a total of three trials.  After each trial was successfully completed, the changes in the pH of the solutions over time were calculated. Mathematical models were used to determine the amount of CO 2 molecules extracted from the air and removed by each solution.  The final results of the experiment were compared and analyzed.

 Independent Variable ◦ Temperature ◦ Concentration of NaOH solution  Dependent Variable ◦ Amount of CO 2 removed  Constants ◦ Erlenmeyer flasks, aquarium pumps, Vernier temperature probes, Vernier pH probes, stirring rods, small weights, Logger Pro Data Logger, computer

 Stabilizing temperature  Limited materials  Evaporation of the NaOH solutions over the 24-hour time period  Time restrictions

 At 16°C, the.1 M NaOH solutions were more effective than the 1 M solutions.  At 32°C, the.1 M solutions produced similar results, but the 1 M solutions removed more molecules of CO 2. The final results suggested that the 1 M solutions were more effective at 32°C.  This refutes the hypothesis that the CO 2 extracted would increase as the concentration of the NaOH solution increased.  It was also hypothesized that the CO 2 extracted would increase as the temperature of the system increased. This was rejected for the.1 M solutions but accepted for the 1 M solutions.  Lower concentrations of NaOH are likely to be more effective at cooler temperatures, and greater concentrations of NaOH at warmer temperatures.  Further Research ◦ Cost-effectiveness, carbon disposal and storage, different concentrations of NaOH solutions

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