The Effect of Ion-Exchange Resins on the Removal of Atmospheric Carbon Dioxide

By: Marina Karki

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Abstract:

The burning of fossil fuels releases millions of tons of carbon dioxide into the air every year creating a current atmospheric concentration of over 400 ppm ^[1]. This high concentration level leads to the melting of sea ice, ocean acidification and wide array of problems that go underly global climate change^[2]. However, lowering the amount of fossil fuels burned globally to acceptable standards seems difficult due to political and economic barriers. For example, in 2017, the United States withdrew from the Paris Climate Agreement, a deal between countries to lower emissions ^[3] Accordingly, carbon capture technologies could serve as a secondary solution to increasing greenhouse gases. One such technology are ion-exchange resins, which offer a cheap and effective way to remove CO₂ from the atmosphere. Ion-exchange resins are small plastic beads that contain a mobile hydrogen ion. This ion reacts with the air to convert atmospheric CO₂ into bicarbonate^[4]. This project was designed to see how efficient chloride ion-exchange resins would be in performing this conversion. The resin beads were embedded into polypropylene sheets that were cut to form four tower s. Two towers were tested in higher concentrations of CO₂ using car exhaust, while two were tested in lower concentrations using dry ice. For all towers, there was a statistically significant difference between the initial and released concentrations, showing that stored CO₂ was released when exposed to water. There was some difference in the amount of CO₂ released between the dry ice and the car exhaust towers, however the minute difference can be attributed to the low temperature of dry ice which caused the beads to contract.

Introduction:

The objective of this project was to test the effectiveness of technology previously tested by Lackner in his studies on carbon capture with ion hydration^[5]. A few aspects of the project were changed such as the technique used to melt the polypropene sheets and imbed the resins beads into the sheets. The shape of the resin model by SquidPoxy USA Epoxy Resin Supplier was also original design. Lastly, the testing method for the amount of stored CO₂, and the different environments tested for were not included in the original study. Lackner concluded that ion-exchange resins with a hydroxide mobile ion will react with atmospheric carbon dioxide to form bicarbonate, serving as an efficient carbon capture technology. Thus, this experiment aimed to verify those results and test the resins in different CO₂ concentrations.

Literature Review:

Carbon dioxide is a colorless gas known for its importance in supporting the life of many organisms on Earth. Plants use it in photosynthesis to produce oxygen, so an absence of carbon dioxide means plants are unable to produce the oxygen needed to support many organisms.^[6] However, too much carbon dioxide can contribute to issues like ocean acidification or global climate change.^[7] There is carbon dioxide in the atmosphere that is naturally produced through the process of cellular respiration where organisms take in oxygen and release CO₂ (C₆H₁₂O₆ + 6O₂ –> 6CO₂ + 6H₂O). Land features like volcanoes and hot springs also release CO₂ naturally by dissolving it from carbonate rocks (CaCO₃ + SiO₂ –> CO₂ + CaSiO₃). However if these natural sources were the only ones producing CO₂, the concentration of it in the atmosphere would be lower than the concentration today of over 400 ppm (parts per million).^[8] The primary anthropogenic source of CO₂ can be attributed to the burning of fossil fuels and deforestation.^[9]

Fossil fuels are fuels naturally produced from dead organisms exposed to extreme heat and pressure underneath Earth’s crust; these carbon-heavy fuels release carbon dioxide when burned. They are burned for a multitude of reasons, but one key reason is to produce electricity as the leading source of power in the world.^[10] Certain fossil fuels release more CO₂ than others, with coal emitting 228.6 lb. per million Btu of energy while natural gas only emits 117 lb. per million Btu of energy.^[11] Nevertheless, in 2014, the burning natural gas emitted about 6,701 million tonnes of CO₂ by itself.^[12]

Deforestation is another major anthropogenic cause for the increase in carbon dioxide concentration; about 15% of these added emissions are a direct effect of deforestation. Not only are humans cutting one of the major sources of carbon uptake, but the vegetation that is cut is often burned afterwards releasing all the carbon dioxide stored in the biomass. Also, deforestation agitates the landscapes and changes how carbon is stored in soil. The soil disturbance leads to increased rates of decomposition which generates more carbon dioxide emissions.^[13]

All this excess CO₂ going into the atmosphere is causing changes and problems throughout the globe. One of the main issues being the fact that CO₂ is a greenhouse gas, meaning that it traps heat in the atmosphere. This is good in small quantities as the planet would be -18 degrees Celsius without carbon dioxide, however an excess can lead to worldwide temperature increases^[14]. These warmer temperatures can cause more frequent and severe hurricanes, floods, and intense droughts along with a rise in sea levels and an increase in heat strokes, incurring major damage costs and hundreds of deaths.^[15] There are also impacts that will affect wildlife and the environment, like ocean acidification. Since the ocean is a carbon sink, as the concentration of CO₂ in the atmosphere increases, so does the amount of CO₂ dissolved into the ocean. The dissolved CO₂ reacts with water to produce carbonic acid. (CO₂ + H₂O –> H₂CO₃). This reaction has been increasing the acidity of the ocean, and subsequently dissolving the shells of mollusks and coral reefs. It also takes carbonate ions from the ocean which those same organisms need to build their skeletons/shells.^[16]

Due to the reliance of mankind on the burning of fossil fuels for energy, it has become difficult to pass legislation restricting the amount of CO₂ emissions produced^[17], so carbon capture is another option to mitigate the consequences caused by an excess of CO₂. In addition, the removal of CO₂ from the atmosphere is necessary as the concentration of CO₂ is already very high, at over 400 ppm^[18]. There are multiple natural and man-made sources that can remove CO₂ from the atmosphere. Photosynthesis and weathering of carbonate rocks are both ways that CO₂ is removed from the atmosphere naturally. However, neither of these can remove carbon dioxide fast enough to even balance out the rate at which carbon dioxide is emitted.^[19] Hence, carbon capture technology has been advancing in recent years. Biochar, carbon scrubbers, quicklime, and sodium hydroxide are all technologies on the forefront of carbon capture.^[20] However, one unique technology is using ion-exchange resins to convert carbonate and CO₂ into bicarbonate.

Ion-exchange resins are small plastic beads (0.5 mm diameter) which have a fixed ion that has been permanently attached, and a mobile ion (a counterion) that can move in and out of the bead. There has to be an ion going in for every ion going out to preserve the electrical neutrality of the bead^[21]. In this case, the resin has mobile chloride ions that will actually be replaced by hydroxide ions when soaked in sodium hydroxide, so it can react with the CO₂ in the air. The resin particles also have to be embedded into an inert polypropylene sheet where the resin should make up 60% of the sheet’s weight in order for it to work properly^[22]. The most effective shape of the sheet is to be thin and similar to a shaggy carpet to allow the greatest exposure to CO₂.

The hydroxide ions in the resin react to form carbonate ions which then react with the CO₂ and water vapor in the air to form bicarbonate.

CO₃^2-+ CO₂+ H₂O → 2HCO₃^–

The bicarbonate can subsequently be converted back to carbonate and release the CO₂ by soaking the sheets in pure water. This material has low-bidding energy and fast reaction kinetics, allowing it to absorb and release the CO₂. Millions of these artificial trees would be necessary to drop the concentration of CO₂ by 0.5 ppm per year through removal ^[23]; however the stored CO₂ can replace fossil fuels as an energy source reducing the CO₂ emission rate.

Materials:

The materials needed for the experiment were a constant continuous flow of CO₂ (exhaust pipe), a 1 M sodium hydroxide solution (40 g of NaOH and 1 Liter of distilled water), Marathon A Chloride Anion Ion-exchange Resin (180 grams), one polypropylene sheet (1/32\” x 24\” x 48\”), a hot plate, an acrylic case (5 3/8\” x 71/4\” h), tubing, a heat-safe glass container, an electric scale, a 1\” diameter plastic rod, a carbon dioxide probe, a Lab Quest, parchment paper, distilled water, a wash bottle, dry ice (4.5 pounds), a drill, and a boxcutter.

Procedure:

A boxcutter was used to cut down the large 1/32” x 24” x 48” polypropylene sheet to 1/32” x 6 cm x 91 cm. In order to get the measured mass of the sheet closer to 80 grams and lessen any error, excess polypropene was cut off. The sheet was then cut into small squares that were approximately 6 cm x 6 cm.

After being cut, the pieces were put in a 250mL beaker and placed on a hot plate. Before turning the hot plate on, 120 grams of the chloride ion resin powder was measured out into a container. Additionally, a heat-safe pan was covered with a piece of parchment paper that had a 10 cm by 54.6 cm square drawn on it. The polypropylene was then melted on high heat until it could be smoothly stirred. Hot hands were used in the handling of the hot plate and the hot glassware to reduce the risk of burns. The melted plastic was quickly poured onto the parchment paper with the drawn square. Moreover, the mixture had to stay within the drawn box and stay about 1/32 inches thick in order to ensure that the sheet was an even rectangular shape. This assured that the model pieces cut from the sheet had similar surface areas and reduced error in the CO₂ readings later on.

Next, the measured resin beads were poured into the polypropylene until they were partially embedded into the sheet. After the sheet dried, they were pretreated by soaking in 85- 95 degrees Celsius deionized water for 48 hours. This opened up the resin pores and expanded the size of the resin sheets. Then, the sheets had to be soaked in the 1.0 M sodium hydroxide solution for 3 hrs 5 or 6 times; this replaced the chloride ions in the resin with hydroxide ions which are necessary for the reaction to occur.

To make the 1.0 M hydroxide solution, a volumetric flask was filled with 1 L of distilled water. Forty grams of NaOH was then slowly added to the flask using a spatula. While adding the NaOH, the edges of the flask were washed down with water to make sure any NaOH sticking to the sides dissolved, and the concentration of the solution stayed accurate.

Once soaked, the large sheet was cut into 8 smaller sheets of 5 cm by 5 cm. Also, the 1” thick support rod was cut into four 3/8-inch tall rods. One rod was glued in between two sheets to form a tower; this was continued until 4 towers of 2 sheets were made. A 1/4th inch hole drilled into the top of the acrylic case, and then Tower 1 was placed inside. Next, one-fourth pound of dry ice was poured through the drilled hole. Insulated gloves were worn when handling the ice to ensure safety as the dry ice presents medium risk if touched directly. After pouring in the ice, the CO₂ probe (connected to the LabQuest) was placed through the drilled hole.

A CO₂ measurement was taken every minute till the ice fully melted. Once melted, measurements were taken per minute for 5 minutes. The dry ice steps were used again with Tower 2, but instead with one pound of dry ice. Then, Tower 3 was placed into the acrylic case. Tubing was used to connect the source of CO₂ (exhaust pipe of a vehicle) into the drilled hole into the acrylic case. The entrance of the tubing was secured to the sides of the hole using putty and tape. Before turning on the gas flow, the same CO₂ sensor was placed through the drilled hole. Once CO₂ began to steadily flow into the case, the CO₂ levels were measured every minute for 10 minutes. After turning off the gas flow, the CO₂ levels in the box were measured every minute for an additional ten minutes. Tower 4 was also used in the car exhaust setting, but with the car exhaust running for 10 minutes. Lastly, the bicarbonate was turned back into CO₂ and released from all towers by pouring pure water over them. One minute later, the probe was placed back into the hole to take the CO₂ reading. The procedures for testing were repeated three times for each tower.

Results:

According to the Averages of the Four Methods (Table 5), the initial atmospheric CO₂ concentration of 408 ppm had a mean decrease of 72 ppm by the end of the experiment with the final concentration being around 336 ppm. Throughout all the trials, the CO₂ levels reached a concentration near or above 100,000 ppm, and the final concentration stabilized in the 300s range. The Dry Ice (1/4 lb) Averages (Table 2) shows that these trials had a much higher difference of 107 ppm between initial and final readings, and the t-tests conducted show that the difference for all four methods is statistically significant.

The amount of carbon released by the resin sheets is the difference between the initial and final CO₂ reading of the sheets soaked in water. On average, the released CO₂ concentration was 598 ppm making it around 262 ppm higher than the final (Table 5). The Car Exhaust (10 min) Averages (Fig. 2) had the highest difference of 277 ppm between final and released concentration while the Dry Ice (1 lb) Averages (Table 1) had the lowest of around 228 ppm. Additionally, the released concentration of 592 ppm in Table 1 was lower than the Table 4 average by 12 ppm. Once again, the differences between the released and final atmospheric CO₂ concentrations were statistically significant. The final piece of information is the difference between the initial reading and the released reading to make sure additional CO₂ has been added. On average, the difference between the two was 190 ppm with the greatest being 198 ppm (Table 4) and the lowest being 188 ppm (Table 1). All of the differences were in the upper 100s (Table 5) making it more certain that CO₂ was added, and in addition, these differences were statistically significant according to the t-tests conducted.

 

Table 1: Dry Ice (1 lb) Averages

	Initial	Final	Released	Diff. between Initial & Release	Diff. between Final & Release	Diff. between Initial & Final
CO2 Concentrations	415 ppm	364 ppm	592 ppm	177 ppm	228 ppm	51 ppm

Table 2: Dry Ice (1/4 lb) Averages

	Initial	Final	Released	Diff. between Initial & Release	Diff. between Final & Release	Diff. between Initial & Final
CO2 Concentrations	410 ppm	303 ppm	598 ppm	188 ppm	295 ppm	107 ppm

Table 3: Car Exhaust (5 Min) Averages

	Initial	Final	Released	Diff. between Initial & Release	Diff. between Final & Release	Diff. between Initial & Final
CO2 Concentrations	402 ppm	349 ppm	596 ppm	194 ppm	247 ppm	53 ppm

Table 4: Car Exhaust (10 Min) Averages

	Initial	Final	Released	Diff. between Initial & Release	Diff. between Final & Release	Diff. between Initial & Final
CO2 Concentrations	406 ppm	327 ppm	604 ppm	198 ppm	277 ppm	79 ppm

Table 5: Averages of Four Methods

	Initial	Final	Released	Diff. between Initial & Release	Diff. between Final & Release	Diff. between Initial & Final
CO2 Concentrations	408 ppm	336 ppm	598 ppm	190 ppm	262 ppm	72 ppm

Figure 1. CO₂ Concentration Comparisons

Figure 2. Car Exhaust CO₂ Concentrations Ocer Time

*After Minute 5, the Exhaust was turned off. Also the CO₂ concentration 1 minute after the resin sheets were washed, releasing trapped CO₂ , was 596 ppm.

Figure 3. Dry Ice CO₂ Concentration over Time

*Dry Ice fully melted around the 30 minutes mark. The average CO₂ concentration 1 minute after the water was used to release the CO₂ in the sheets was 598 ppm

 

Discussion:

In relation to the overall effectiveness of the resin beads, all the environments did show a statistically significant decrease between the initial and final concentration indicating an overall drop in CO₂ concentration of the test area In addition, the statistically significant difference between the final and the released concentrations for all environments supports the idea that the resin does absorb CO₂. Finally, the difference between the released and the initial concentrations indicates that the CO₂ concentration does not return to a ppm in the 400s range, but rather that there is CO₂ being added to the atmosphere by the sheet (Table 5). This supports the research done previously by Lackner and other scientists on ion-exchange technology in carbon dioxide absorption.^[24]

The different test environments show similar trends, but one discrepancy can be seen. The dry ice environments tended to have lower average amounts of CO₂ absorbed and then released. However, this doesn’t seem to be caused by the lower concentration levels or an error in the experimental procedure. Instead, it appears that the cold temperatures caused by the dry ice may have led to the resin beads to contract slightly. For example, the trial with 1 lb of dry ice had the lowest average concentration differences, and had the beads exposed to the cold the longest (Table 5). Additionally, multiple research papers do state the beads must be soaked in warm water in order to expand their size, although there is not specific research done about the effect of temperature on the beads. Initially, the expectation was that the concentration would end up affecting the amount of CO₂ absorbed, but it seems as the size of the sheets or exposure of the beads has the greatest effect on the amount of CO₂ absorbed with temperature having a minute effect. This idea would match the established concept that the beads have a set volume and will only hold a set amount of CO₂.

Therefore when applied to real life, the sheets would have to be thin allowing the beads as much exposure as possible. The size of the sheet would reflect the amount of CO₂ to be contained, so it would have to vary based on the application. For example, the resin sheets could be used on a mass scale to capture CO₂ which can be converted into ethanol for energy. In this case, the sheets would have to have a large surface area in order to maintain the level of production needed. The model used in this experiment would not be effective; it would have to resemble more of a shag carpet or pine needle shape to allow the maximum amount of exposure. Different model shapes and surface areas could be tested in the future to discover the most efficient design, In regards to climate, the model could be used in all climates as the extreme coldness of the dry ice barely had an effect on the efficiency of sheets. Additionally, humidity would not cause a major impact on the sheets’ function as only pure water can turn the bicarbonate back into CO₂. This makes the technology more applicable to different climates and conditions around the world expanding its potential in the carbon capture field.

Conclusion:

This experiment was designed to test the effectiveness of the ion-exchange resin beads in removing atmospheric CO_2, with regard to varying concentrations of CO₂. The results support the idea that the resin model was effective in absorbing CO₂ due to the statistically significant difference between the concentrations taken and the start and end of the experiment. Specifically, the released concentration was on average 262 ppm higher than the final concentration (Table 5) showing that a significant amount of stored CO₂ was released from the towers. This finding suggests that the adapted procedure used to create a less costly version of the models did not cause any errors that prevented them from serving their purpose.

However, the concentration of the test area did not seem to make an impact on the CO₂ absorbed. Instead, temperature was shown to be a possible factor for the absorption discrepancies. The results indicate that the colder temperatures caused by dry ice environments caused the beads to contract, decreasing the volume of CO₂ absorbed. However, this small difference in absorption would not prevent the usage of the technology in colder climates. The research was not only able to test the validity of the original technology, but also the impact of different factors, like the procedural changes, temperature, and CO₂ concentration, allowing for a more comprehensive report on the effectiveness of ion-exchange resins.

Limitations:

This project was modelled after a similar experiment done with high-cost equipment that was not accessible for this experiment, and there were certain methods that could have been refined. For example, the polypropylene sheets had to be melted in order to mix the resin beads in. This process was time-consuming, andthe sheets were easy to burn, so it may be advantageous to use a more heat-resistant plastic in future research. Additionally, the container used had some gaps, and although they were covered to minimize the amount of CO₂ lost, fewer gaps could lead to more precise results.

Applications:

The high levels of atmospheric carbon dioxide is a major concern as it leads to multiple high risk problems. From causing ocean acidification to sea levels rising, this simple problem can lead to major damage done to the planet and to communities around the world^[25] . A possible solution to this issue is to remove CO₂ from the atmosphere at a pace where it is negating the amount that is put in every day. This technology could be used to create cost-efficient artificial trees that would remove CO₂ from the atmosphere. This plastic could be employed in fake plants that consumers buy. So even though it is a fake plant that they do not need to take care of, it is still performing the actions of a real one. Furthermore, with additional research, the carbon stored can be used as an energy source, minimizing the need for additional burning of fossil fuels.

Acknowledgements:

First, I would like to thank my father and my mother for supervising my experiment and making sure I was safe at all times. I would like to thank my school and teachers for allowing me to use their laboratories as a safe place to perform any chemical reactions. Additionally, I would like to thank my teacher, William Bartenslager, for allowing me to use materials that I did not have and buying any materials, such as the resin, that I needed. Lastly. I would like to thank all the scientists, friends, and teachers who taught me about this topic and encouraged my interest in this experiment.

References:

1. University of Berkeley, “What is a greenhouse gas?” Modified 2017. Accessed November 8, 2017, http://beacon.berkeley.edu/GHGs.asp.
2. Melissa Dencark. “Are the effects of Global Warming Really that bad?” NRDC , March 15, 2016, https://www.nrdc.org/stories/are-effects-global-warming-really-bad
3. Timmons Robers. “One year since Trump’s withdrawal from the Paris climate agreement.” The Brookings Institution, June 1, 2018, https://www.brookings.edu/blog/planetpolicy/2018/06/01/one-year-since-trumps-withdrawal-from-the-paris-climate-agreement/
4. Tao Wang, Klaus S. Lackner, & Allen Wright. “Moisture-swing sorption for carbon dioxide capture from ambient air: a thermodynamic analysis.”Environmental Science & Technology, 45, 2 (2011), 6670–6671. doi:10.1039/c2cp43124f
5. Xiaoyang Shi, Hang Xiao, Klaus S. Lackner, & Xi Chen . “Capture CO2 from Ambient Air Using Nanoconfined Ion Hydration.”, Angewandte Chemie International Edition, 55, 12 (2016), 4026-4029. doi:10.1002/anie.20150784
6. “Carbon Dioxide”, UCAR Center for Science Education, accessed November 8, 2017. https://scied.ucar.edu/carbon-dioxide
7. “Main sources of carbon dioxide emissions,” What’s Your Impact.org, accessed November 8, 2017. https://whatsyourimpact.org/greenhouse-gases/carbon-dioxide-emissions
8. Geetha Kanniah, Student Energy, “Fossil Fuels”. Accessed November 8, 2017, https://www.studentenergy.org/topics/fossil-fuels
9. “How much carbon dioxide is produced when different fuels are burned?” EIA. Modified June 8, 2017. Accessed November 8, 2017. https://www.eia.gov/tools/faqs/faq.php?id=73&t=11
10. Boden, TA, Marland, G and Andres, RJ 2013. Global, Regional, and National Fossil-Fuel CO2 Emissions, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Department of Energy, Oak Ridge, Tenn., USA doi 10.3334/CDIAC/00001_V2013
11. “Climate Change Indicators: Greenhouse Gases.” EPA. Accessed November 8, 2017. https://www.epa.gov/climate-indicators/greenhouse-gases
12. “Deforestation and Forest Degradation”, WWF, accessed on Nov 8. 2017, https://www.worldwildlife.org/threats/deforestation-and-forest-degradation
13. “What is Ocean Acidication?”, National Ocean Service, accessed November 8, 2017, https://oceanservice.noaa.gov/facts/acidification.html
14. IPCC, IPCC Special Report on Carbon Dioxide Capture and Storage. (New York, New York: Cambridge University Press, 2005) 105-115
15. “Ion Exchange for Dummies”, Rohm and Hass. accessed October 1, 2017, https://www.lenntech.com/Data-sheets/Ion-Exchange-for-Dummies-RH.pdf
16. Klaus Lackner, “Capture of carbon dioxide from ambient air,” Eur. Phys. J. Spec. Top. 176 (2009): 93-106, doi:10.1140/epjst/e2009-01150-3
17. Lackner, K. Eur. Phys. J. Spec. Top. (2009) 176: 93. doi:10.1140/epjst/e2009-01150-3
18. Dowex 1X8-50 Ion Exchange Resin; MSDS No. D3645X [Online]; Spectrum Laboratory Products INC: Gardena, CA, Nov 9, 2012. https://www.spectrumchemical.com/MSDS/D3645X.pdf (accessed September 1, 2017)
19. Sodium Hydroxide Solution; MSDS No. 26500TDC [Online]; TDC, LLC: Ruston, LA, Sep 12, 2010. http://www.ibpmidwest.com/sites/default/files/documents/MSDS_Caustic_50_TDC_2010.pdf (accessed September 1, 2017)

Appendix: Dry Ice and Car Exhaust Concentrations Over Time

Dry Ice (1 lb) CO₂ Concentration Over Time

Time	Trial 1	Trial 2	Trial 3	Average
Initial	420 ppm	421 ppm	404 ppm	415
1 Min	84000	83200	83240	83480
2 Min	94860	95740	96545	95715
4 Min	90000	91010	92980	91330
2 hr (when ice fully melted)
2 hr 10 Min	27050	26000	25450	26167
2 hr 20 min	10600	11700	11100	11133
3 hr	7800	8050	8789	8213
4 hr	6572	5425	6114	6037
5 hr	1500	1482	1518	1500
6 hr	920	894	917	910
7 hr	360	375	356	364

*After the last reading, water was added to the sheets to release any stored CO₂. One minute after this release, the CO₂ Concentration of the box was an average of 592 ppm

Dry Ice (1 lb) Initial Vs Final

Descriptive Information	Initial	Final
Mean	415 ppm	364 ppm
Variance	91 ppm	101 ppm
Standard deviation	9.5	10
1 SD (68% Band)	405.5-424.5	354-374
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 6.375 > 2.306	Alpha = 0.05 p > 0.10

Dry Ice (1 lb) Initial Vs Released

Descriptive Information	Intial	Released
Mean	415 ppm	592 ppm
Variance	91 ppm	247 ppm
Standard deviation	9.5	15.7
1 SD (68% Band)	405.5-424.5	576.3-607.7
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 16.675 > 2.306	Alpha = 0.05 p > 0.10

Dry Ice (1 lb) Released Vs Final

Descriptive Information	Released	Final
Mean	592 ppm	364 ppm
Variance	247 ppm	101 ppm
Standard deviation	15.7	10
1 SD (68% Band)	576.3-607.7	354-374
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 21.169 > 2.306	Alpha = 0.05 p > 0.10

Dry Ice (1/4 lb) Initial Vs Final

Descriptive Information	Initial	Final
Mean	410 ppm	303 ppm
Variance	6.5 ppm	63 ppm
Standard deviation	2.5	7.9
1 SD (68% Band)	407.5-412.5	295.1-310.9
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 22.2 > 2.306	Alpha = 0.05 p > 0.10

Dry Ice (1/4 lb) Initial Vs Released

Descriptive Information	Initial	Released
Mean	410 ppm	598 ppm
Variance	6.5 ppm	170 ppm
Standard deviation	2.5	13
1 SD (68% Band)	407.5-412.5	585-611
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 24.5 > 2.306	Alpha = 0.05 p > 0.10

Dry Ice (1/4 lb) Released Vs Final

Descriptive Information	Released	Final
Mean	598 ppm	303 ppm
Variance	170 ppm	63 ppm
Standard deviation	13	7.9
1 SD (68% Band)	585-611	295.1-310.9
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 33.4 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (5 Min) Initial vs Final

Descriptive Information	Initial	Final
Mean	402 ppm	324 ppm
Variance	133 ppm	150 ppm
Standard deviation	11.5	12.1
1 SD (68% Band)	390.5-413.5	311.9-336.1
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 6.132 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (5 Min) Initial vs Released

Descriptive Information	Initial	Released
Mean	402 ppm	596 ppm
Variance	133 ppm	20.5 ppm
Standard deviation	11.5	4.5
1 SD (68% Band)	390.5-413.5	591.5-600.5
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 26.8 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (5 Min) Released vs Final

Descriptive Information	Released	Final
Mean	596 ppm	324 ppm
Variance	20.5 ppm	150 ppm
Standard deviation	4.5	12.1
1 SD (68% Band)	591.5-600.5	311.9-336.1
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 36.08 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (10 Min) Initial vs Final

Descriptive Information	Initial	Final
Mean	406 ppm	327 ppm
Variance	22.5 ppm	160.5 ppm
Standard deviation	4.7	12.7
1 SD (68% Band)	401.3-410.7	314.3-339.7
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 10.1 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (10 Min) Initial vs Released

Descriptive Information	Initial	Released
Mean	406 ppm	604 ppm
Variance	22.5 ppm	49.5 ppm
Standard deviation	4.7	7
1 SD (68% Band)	401.3-410.7	597-611
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 40.4 > 2.306	Alpha = 0.05 p > 0.10

Car Exhaust (10 Min) Released vs Final

Descriptive Information	Released	Final
Mean	604 ppm	327 ppm
Variance	49.5 ppm	160.5 ppm
Standard deviation	7	12.7
1 SD (68% Band)	597-611	314.3-339.7
Number	3	3
Results of t-test	t = 2.776 df = 4 t of 33.1 > 2.306	Alpha = 0.05 p > 0.10

Biography

 Marina Karki is a sophomore attending Rice University in Houston, Texas. Her interest in science began when she was young and now over the years, she has pursued more and more opportunities in the scientific field whether it be completing in science fair during her high school career or getting involved with a research lab in college. She also hopes to continue her interest in environmental sciences with a future career in Environmental Engineering.