Absorption of CO Using Water as the Solvent - Research Paper Example

Gas absorption: CO2 absorption Process from CO2/air mixture using water as a solvent Name: Date of experiment: Date of report: Summary This paper presents absorption of CO2 using water as the solvent. The paper demonstrates the factors affecting the absorption of CO2 alongside the demonstration make readings of pressure drop and validating data to find the overall coefficient transfer of CO2 in water during the absorption. To achieve this, this paper presents how the experiment used the method of The gas absorption pilot plant uses a column of fixed height, containing 10 mm raschig rigs, with water as the solvent flowing down the column, operating in counter-current flow to remove CO2 from a CO2/air mixture. The unit regenerates the solvent in a desorption column using reduced pressure and increased solvent temperature. During the experiment, various factors such as CO2 flow rate, water flow rate and air/Co2 flow rates were varied. The paper finds that increase in water temperature, water flow rate, CO2 flow rate and air/CO2 flow rate increases the rate of CO2 absorption. The Coefficient of mass transfer in this experiment was found to depending on the underlying conditions. The paper concludes to have been effective and its findings near theoretical values thus an effective experimental design in studying the gas absorption and confounding factors. List of figures Figure 1 CO2/Water equilibria at 1 bar pressure for various temperatures in terms of mole ratios. Source: Lab notes 6 Figure 2: Diagrammatic setup of the rig 9 List of tables Table 1: henry's law constants under different conditions 4 Table 2: composition stabilizing {CO2(1L/min), air(1m3/hr),water flow(200L/hr)} 13 Table 3: composition stabilizing {CO2(3L/min), air(1m3/hr),water flow(200L/hr)} 13 Table 4: Composition stabilizing {CO2(5L/min), air(1m3/hr),water flow(200L/hr)} 13 Table 5: Composition stabilizing {CO2(1L/min), air(0.5m3/hr),water flow(200L/hr)} 14 Table 6: Composition stabilizing {CO2(3L/min), air(0.5m3/hr),water flow(200L/hr)} 14 Table 7: Overall coefficient of CO2 mass transfer 18 Table of Contents Summary 2 List of figures 3 List of tables 3 1.Introduction 1 1.2Aims 2 2.Theoretical framework 2 2.1 Operating Line Equation 3 2.2Design equation 3 2.3Henry’s Law 3 2.3.1Temperature dependency of Henry’s Law constant 4 3.Material and Methods 6 3.1Startup 6 3.2Sampling 10 3.3Differential pressure measurement 10 3.4Approach 11 3.5Analysis 11 3.6Shut down 11 4Results 13 5Discussion 19 6Conclusion 21 References 23 23 Appendix 24 Experimental shut process 24 Conversion table for air rotameter 25 Column dimensions 25 1. Introduction Scrubbing is the removal of a particular from the air. Carbon dioxide (CO2) is one of those gases commonly scrubbed in different fields of application including, but not limited to, life support machines (rebreathers), submarines, spacecrafts and more interestingly, scrubbing of CO2 from the atmosphere in efforts to fight global warming ("How CO2 Scrubbing Works", 2017). This paper is a report presenting the experiment studying the behavior of gas absorption of the carbon dioxide (CO2) from CO2/air mixture using water as the solvent under different conditions as well as the overall coefficient mass transfer of CO2 in the water. A pilot absorption pilot plant is usually used for this kind of experiment. The gas absorption pilot plant uses a column of fixed height, containing 10 mm raschig rigs, with water as the solvent flowing down the column, operating in counter-current flow to remove CO2 from a CO2/air mixture. The unit regenerates the solvent in a desorption column using reduced pressure and increased solvent temperature. There are various reasons CO2 would need be removed from air. As a result of need for optimal design, the way CO2 absorption behaves under certain conditions need be understood. This, Budzianowski, (n.d.) says is in accordance with economic considerations and scientific methods to maximize the activity. Budzianowski, (n.d.) explains that water is an ideal CO2 absorbent and is a preferred solvent of choice due to energy efficiency among other operating considerations. Based on the same aspects of preference this experiment used water as the absorbent. Budzianowski, (n.d.) suggests that under different conditions, the absorption behaves differently. These conditions and the absorption behavior need be understood for better optimization of the process (Burg, 2004). Burg (2004) outlines some of the factors of gas absorption to include temperature, pressure, and concentration. Others include the effect of inlet gas composition, the ratio of inlet gas flow rate to the flow rate of liquid solvent. Based on the fact that gas absorption is affected by many factors therefore, this experimental design aimed at understanding the factors among other things as can be clearly shown in the experimental design objectives/aims below. 1.2 Aims 1. To study the effects of variable water flow rate at (a) constant air/CO2 composition (b) constant water temperature. 2. To study the effect of CO2 flow rate a constant air/CO2. Water temperatures and water flow rate. 3. To study the effects of variable air/CO2 flow rate at (a) constant water flow rate (b) constant air/CO2 composition. 4. To study the effect of water temperature at a constant water flow rate, constant air/CO2 composition and flow rate. 5. Observe the pressure drops at various air/CO2 and water flow rates. 6. To practice standard procedures for validation of data collection and processing. 7. To determine the Overall Mass Transfer Coefficient, 𝐾𝐺𝑎 for the absorption column. The objectives were arrived under a good theoretical framework as shown in the chapter 2 below. 2. Theoretical framework There are underlying assumptions behind this experimental design. Given the factors mentioned above, to perform the calculations assumed that the Desorption column K2 completely regenerates the water solvent. A state of equilibrium is attained under the operating line equation below 2.1 Operating Line Equation 𝐺𝑚 (𝑌2 − 𝑌1) = (𝑋2 − 𝑋1) Where: X, Y are mole ratio’s Gm = Gas molar flow rate, at standard temperature and pressure, on a solute free basis. Lm = Liquid molar flow rate, at standard temperature and pressure, on a solute free basis. 1 denotes top of the column, 2 denotes base of the column 2.2 Design equation 2.3 Henry’s Law Henry is chemist whose research in this field of gas absorption by water is commendable. Henry’s law states that "water takes up, of gas condensed by one, two, or more additional atmospheres, a quantity which, ordinarily compressed, would be equal to twice, thrice, &c. the volume absorbed under the common pressure of the atmosphere." (Lee, 2007). Basically this, Lee (2007) interprets to a better version that the amount of dissolved gas is proportional to its partial pressure in the gas phase. The proportionality factor is called the Henry's law constant. Different gases would have different constants under different conditions. Below is the henry’s Law constant for CO2 in water at 298 K is presented in Table 1 for number of possible forms of the equation. Table 1: henry's law constants under different conditions From Henry’s statement, temperature is a factor. Below is a description of temperature dependency on Henry’s constant law 2.3.1 Temperature dependency of Henry’s Law constant Depending on the temperature of the water used as a solvent in the absorption column, the value of the Henry’s law constant will change. This temperature dependency is expressed as follows. 𝐻𝑖, = 𝐻𝑖,𝑝,𝑇298𝑒𝑥𝑝 [𝐶 (𝑇 1 – 𝑇1 298)] Where: T = Water temperature in K T298 = 298 K (standard temperature) C = 2400 K (Constant for CO2) To convert Hi,cp into a format that you can use to plot the equilibrium curve, you need to convert Hi,cp into the form Hi, px. This is done as follows: 𝐻𝑖,𝑝𝑥 = 𝜌𝑤𝑎𝑡𝑒𝑟 𝑅𝑀𝑀𝑤𝑎𝑡𝑒𝑟𝐻𝑖,𝑐𝑝 Where: ρwater = 1 kg.L-1 RMMwater = 0.018 kg.mol-1 Equilibrium curves may be plotted, in terms of Mole Ratios X and Y, for each water temperature used, where: 𝑌𝑖 = 𝐻𝑖, 𝑃 𝑋𝑖 1 + (1 − 𝐻𝑖 ,𝑥) 𝑋𝑖 P = Pressure in Absorber in units of atmospheres. (Typically the absorber is operating under atmospheric conditions.) A graphical presentation of the temperature dependency of Henry’s law constant is as shown in the figure 1 below. With this theoretical framework in mind, the experiment was carried as described in section 3 below. Figure 1 CO2/Water equilibria at 1 bar pressure for various temperatures in terms of mole ratios. Source: Lab notes 3. Material and Methods 3.1 Startup Before starting the experiment in pursuit of the experimental objectives, preparations were made as shown below. First was the familiarization process with the rig and how to use the CO2 meter. Valves were checked and closed (all the 3 ball valves and the V20 and V21). The absorption unit was turned on at the mains, and then at the control panel. W2/W3 cooler units were filled to the level of the inspection glass. P3 was started and set point TC 2 adjusted to 5oC and then waited for 30 minutes to stabilize the temperatures. Fresh water supply was connected. The solvent levels (water) was in K1 was filled to 10cm and K2 filled to half full. V10 and V19 were fully opened and V17 was opened 3 full turns. Pumps P1 and P2 were opened while simultaneously opening and adjusting V12 to give an initial flow of 200 L/hr on FI 03. The water level in K2 should remain steady at 1/3 full. V17 was adjusted until the spray cone in K2 was reduced to a minimum. The heater A2 were switched on and T2 adjusted to 40oC. The air compressor V was turned on while simultaneously opening V2 to set the initial flow rate of 1m3/hr. with V19 closed V20 was opened to apply a vacuum at K2. V20 was set to relative vacuum to the closest 0.5 bar. V21 was opened slowly until air bubbles were observed through the liquid in K2 and the level of pressure in K2 monitored. This was with caution that high pressure would occasion water to flow out of the air filter installed before V21. A staff member opened CO2 from gas bottle and the pressure regulator set to 0.8 bars. V1 was then adjusted to set an initial flow of 1 L/min of CO2 on F1 01. See figure2 below of the material set up This was just setting up for the experiment. After this , the experiment was ready for adjustment of variables in pursuit of the experimental aims. The variables in this case included air/CO2 flow rate, water flow rate and the water temperature. Before moving on to the next step, it is important to note that not all the operating conditions noted in the equations will be used. The variable ranges were given by staff as shall be seen in the results table in the results section. Figure 2: Diagrammatic setup of the rig Having set up for the experiment as described above, the changing of parameters was ready. It’s important to note that whenever a parameter was changed, the column was given 20 minutes to stabilize before taking measurements. 3.2 Sampling Co2 meter was used for sampling. For each experiment, a sample was taken from the bottom, middle and top of the column as shown below: To take a sample from column gas inlet (S1), V4 was opened and the line allowed to purge for 10 seconds before connecting CO2 meter to take reading. V4 was then closed once the reading had been taken. To take sample from the middle of the column (S2), V5 was opened and procedure for repeated as shown in V4. For gas outlet, the same procedure was repeated but with V6 this time. 3.3 Differential pressure measurement Pressure measurements were only taken when the liquid level within the column was steady. This was done with caution because if water enters the measuring line for the manometers would easily lead to incorrect measurements. Before taking a measurement. Pressure measurements were done following the procedure below. Before taking a measurement, the 3 ball valves above the U-tube were checked. To determine the pressure drops in the entire column, V8, V9 and V25 were opened. PDI 01 was used to measure the pressure drop across the top half of the column. PDI2 was used to measure the pressure drop across the bottom half of the column. The sum of these is the total pressure drop across the entire column. The measurements were recorded and the valves V8, V9 and V25 were closed. The3 ball valves above the U-tube manometers were then opened to equalize the pressures and then closed. 3.4 Approach To determine the effect of CO2 flow rate on absorption, the pressure drops were observed at 1L/min, 3 L/min, and 5L/min flow rates of CO2. The air/CO2 and water flow rates were kept constant. In order to understand the effect of airflow rate on absorption, the pressure drops were noted for different airflow rates under particular constant CO2 flow rate and water flow rates. In order to determine the effect of water flow rate on absorption, computations were made and plotted for the liquid loading against gas loading. Other experimental aims such as observing the pressure drop and validating were basically observations that meant to achieve the aims which were used in attaining the main objective. To find the overall coefficient of CO2 mass transfer, computations were made about the operating and design equations in 2.1 and 2.2 sections. 3.5 Analysis The results were recorded and transferred to excel sheets where it was easily analyzed bearing in mind the equations in the theoretical section. 3.6 Shut down Having taken into account the measurements of interest, the experiment was concluded following the procedural shut down process as given in the appendix section 1. Based on the outlined aims this experiment carried out varying the water temperature, water flow rate and the CO2 flow rate and time in minutes noted. The results were as recorded in the results section. 4 Results The Results were recorded in tables as shown in the appendix section for observations on changing conditions. Table2, 3, and 4 show observations at 1L/min, 3 L/min and 5L/min CO2 flow rates respectively. The gas temperature is 20oC, water flow rate of 200L/hr and the water temperatures 22oC at K1(absorber) and 38oC at K2 (desorber). Airflow rate was 1m3/hr. The air/CO2 compositions were recorded as well as the changes in pressure for the respective water air/CO2 flow rates. Table 2: composition stabilizing {CO2(1L/min), air(1m3/hr),water flow(200L/hr)} Table 3: composition stabilizing {CO2(3L/min), air(1m3/hr),water flow(200L/hr)} Table 4: Composition stabilizing {CO2(5L/min), air(1m3/hr),water flow(200L/hr)} As can be seen from the above results, there seems to be a larger pressure drop of 16 parts at a CO2 flow rate of 5L/min. This very large compared to the drop of 12 parts at a flow rate of 3L/min and 1L/min. This, therefore, implies that there is noted increase in absorption rate for an increase in the CO2 flow rate, essentially concentration. This gives the answer to objective 2. However, it should be note that the increase is exponential since at 1 and 3 L/min CO2 flow rate, there’s no significant difference in pressure drop but drops more suddenly at 5L/min flow rate. The second experiment was to make observations for the effect of changing airflow rate. Tables 5, 6 show observations made under airflow rate of 0.5m3/hr. During this time, pressure differences were noted. Table 1 can be considered to be the initial condition/state of the experimentation. Table 5: Composition stabilizing {CO2(1L/min), air(0.5m3/hr),water flow(200L/hr)} Table 6: Composition stabilizing {CO2(3L/min), air(0.5m3/hr),water flow(200L/hr)} At CO2 flow rate of 1L/min and air flow rate of 1 m3/hr, the total pressure drop is 12 parts. At 1L/min CO2 flow rate and 0.5m3/hr air flow rate, the total pressure drop is 9. At CO2 flow rate of 3L/min, for air flow rate of 1m3 /hr the pressure drop is 12 parts whereas at 0.5m3/hr flow rate, the pressure drop is 7 for the same CO2 flow rate. In both the 2 cases of CO2, it can be seen that pressure drop is larger for 1M3 /hr flow rate compared to the 0.5m3/hr flow rate. This means that the rate of absorption is high when the air flow rate is higher compared to when it is slower. This answers the third objective. From the tables, all the 5 tables, there is a significant observation about how the column height changes with time. Lee (2007) explains that CO2 absorption is an exothermic process. This means it releases heat of reaction which, Budzianowski (2007) explains leads to increased temperature. In this experimental design therefore, the temperature increase is purely depended on the process thus observations are made under effect of time, that is, as time goes by, temperatures from the process increase. With this in mind, the effect of temperature is observed by changes in height for the middle, top and bottom of the column. As a matter general observation for the mole ratio at the bottom, top and middle of the column, the mole ratio is seen to decrease with time. The bottom is seen to have a generally higher reduction in the mole with time. As for the fourth objective, the pressure drops were observed and recorded as shown in the tables above. All the data relevant for the study was found and all relevant computations done without trouble and in accordance with the expected theoretical framework. This forms the basic answer to objective 4 of this study. Finally was the computation of the transfer coefficient. In order to determine the absorption rate i.e the overall mass transfer coefficient KGα for the absorption, a few computations were done as shown below Final V2 the gas law equation is used. And calculated by hand as shown below From the snapshot V2 (volume flow rate per mole was computed to 20.87 L/mol. With this, and considering the theoretical equations values for h2, Gm, Lm, p, y2, y1 compute to h2 = 1m3/hr= 1000L/hr= 20.87 L/mol Other computations were done on paper and found to be as shown below. Assuming X1 is zero, it follows that Gm(y2-y1)=Lm(X2-X1(0)) And therefore gives the computation as done on paper below With this in mind therefore, combining the recordings into one table, a new table is as shown below. As can be seen from the tables, using excel and the formula below, the overall mass transfer coefficient of CO2 is found to be as shown in the table. Using equation 2.1 for the equilibrium state , the values for the coefficient were computed and filled in the table as shown in the last column below. Table 7: Overall coefficient of CO2 mass transfer The overall coefficient of mass transfer of CO2 under the confounding conditions is given in the last column of the table above. The coefficient, just like the Henry’s law constants is seen to vary depending on the factors such as air/CO2 flow rates, and the CO2 concentration. This is in fact in agreement with Kazim’s report (2012) on who explains that the coefficient of overall mass transfer of CO2 depends on several factors. In the case shown above, other factors notwithstanding, the overall mass transfer coefficients depend on the CO2 flow rates and the air flow rates. Plotting the liquid loading against the gas loading gives the effect of liquid flow rate , in this case water, on the absorption rate. Figure3: Graph showing the operating and the equilibrium curves for this experiment operating curve is in blue and the equilibrium is in red 5 Discussion As seen in the fgure3, at constant temperature, airflow rate and CO2 flow rate, increase in water flow rate is accompanied by increase in CO2 loading. This experimental result conforms to the theoretical framework as seen in the graphical illustration of Henry’s law in figure1 of the theoretical framework. However, there’s a slight difference in the curve probably due to experimental errors that usually happen as explained by PERFETTI & FISHER (1976). Through this experimental part, objective is answered. The effect of water flow rate is explained by (Park, Chang & Lee, 2004 p. 106). He explains that the observation is explained by the fact that increased water flow reduces the surface resistance and increases the permeation rate for the CO2 absorption. From table1, table2 and table3, pressure drop associated with respective increment in the CO2 flow rate show that increase in CO2 under constant water flow rate and airflow rate results in increased absorption of CO2. This is conformal to Hegde, Choi & Xiao, (2002 p.111) assertion which illustrates that increase in gas flow rate enhances the scrubbing process. The trio explain that it is because increase in gas velocity increases the number of bubbles, hence interfacial area increase. This definitely increases the rate of absorption due to increased gas hold-up. The results tables 4, 5 in comparison with 1 and 2 under changing air flow rate, it can be seen that increased airflow rate enhances the absorption process. This is concluded from enhanced pressure drop (which signifies enhanced CO2 absorption) observed when the airflow rate is higher compared to when it’s lower. This conforms to Burg’s findings (2004). Burg explains that increased airflow reduces the saturation gradient at the surface,, hence enhanced absorption due to increased potential gradient of absorption. Observations of the mole ratio with time in all the tables 2 to 5 show reduction in the mole ratio as read from the CO2 meter. The outlet (bottom) shows a larger mole ratio drop compared to the middle and top. From Henry’s explanation in the above section on theory, at the outlet, the temperatures are higher. It therefore follows that increased solvent temperature increases the CO2 loading. This is attributed to the fact that increased solvent temperature increases the reactivity Burg (2004). The coefficient of CO2 mass transfer, KGα, for the absorption under the conditions set in the methodology section is found to vary/to be affected by the prevalent conditions such as the CO2 flow rate and air/CO2 flow rate. The conformity of this finding with that of other studies such as that by Kazim (2012) implies that the study waqs successful. The pressure drops were observed and recorded. These pressure drops were of great use in identifying the level of absorption by looking at the relative drop values under the factor being monitored. With the seamless achievement of the target aims, the experimental design can be recommended. The computations carried out in finding the transport can be said to have helped in validating the data collected for the computation of the coefficient. In this experiment, therefore, it can be said that all the desired observations were made and data validation effectively done towards achieving the objective of determining both the coefficient of mass transfer and the factors affecting the gas absorption. 6 Conclusion This experiment was effectively done and achieved all its objectives. The findings of this paper, can therefore, by extension be applied to an situation of CO2 absorption under the similar conditions as those in this paper. The paper conclusively finds that increase in CO2 flow rate, water flow rate, air/CO2 flow rate and increase in temperature enhances gas absorption, CO2 in this case. This experiment found out that the coefficient of CO2 mass transfer depends on the underlying factors such as CO2 flow rate and/or air/CO2 flow rate. The findings of this study are not far from the empirical/ research/theoretical establishments done earlier. References Budzianowski, W. Energy efficient solvents for CO2 capture by gas-liquid absorption (1st ed., p. 43). Burg, S. (2004). Postharvest physiology and hypobaric storage of fresh produce (1st ed.). Wallingford: CABI Pub. Hegde, G., Choi, S., & Xiao, H. (2002). Advances in chemical engineering and advanced materials IV (7th ed., p. 111). NY: academic press. How CO2 Scrubbing Works. (2017). HowStuffWorks. Retrieved 20 February 2017, from http://science.howstuffworks.com/environmental/green-science/co2-scrubbing.htm Kazim, S. (2012). Experimental & Empirical Correlations for the Determination of the Overall Volumetric Mass Transfer Coefficients of Carbon Dioxide in Stirred Tank Bioreactors. Ontario: The University of Western Ontario. Lee, F. (2007). Comprehensive analysis, Henry's Law constant determination, and photocatalytic degradation of polychlorinated biphenyls (PCBs) and/or other persistent organic pollutants (POPs) (1st ed.). Park, S., Chang, J., & Lee, K. (2004). Carbon dioxide utilization for global sustainability (1st ed.). Amsterdam: Elsevier. PERFETTI, L. & FISHER, T. (1976). GAS ABSORPTION COLUMN. Chem.engr.utc.edu. Retrieved 20 February 2017, from http://chem.engr.utc.edu/Webres/435F/ABS_COL/abs_col.html Appendix Experimental shut process Conversion table for air rotameter Column dimensions Read More

Based on the fact that gas absorption is affected by many factors therefore, this experimental design aimed at understanding the factors among other things as can be clearly shown in the experimental design objectives/aims below. 1.2 Aims 1. To study the effects of variable water flow rate at (a) constant air/CO2 composition (b) constant water temperature. 2. To study the effect of CO2 flow rate a constant air/CO2. Water temperatures and water flow rate. 3. To study the effects of variable air/CO2 flow rate at (a) constant water flow rate (b) constant air/CO2 composition. 4. To study the effect of water temperature at a constant water flow rate, constant air/CO2 composition and flow rate. 5. Observe the pressure drops at various air/CO2 and water flow rates. 6. To practice standard procedures for validation of data collection and processing. 7. To determine the Overall Mass Transfer Coefficient, 𝐾𝐺𝑎 for the absorption column.

The objectives were arrived under a good theoretical framework as shown in the chapter 2 below. 2. Theoretical framework There are underlying assumptions behind this experimental design. Given the factors mentioned above, to perform the calculations assumed that the Desorption column K2 completely regenerates the water solvent. A state of equilibrium is attained under the operating line equation below 2.1 Operating Line Equation 𝐺𝑚 (𝑌2 − 𝑌1) = (𝑋2 − 𝑋1) Where: X, Y are mole ratio’s Gm = Gas molar flow rate, at standard temperature and pressure, on a solute free basis.

Lm = Liquid molar flow rate, at standard temperature and pressure, on a solute free basis. 1 denotes top of the column, 2 denotes base of the column 2.2 Design equation 2.3 Henry’s Law Henry is chemist whose research in this field of gas absorption by water is commendable. Henry’s law states that "water takes up, of gas condensed by one, two, or more additional atmospheres, a quantity which, ordinarily compressed, would be equal to twice, thrice, &c. the volume absorbed under the common pressure of the atmosphere.

" (Lee, 2007). Basically this, Lee (2007) interprets to a better version that the amount of dissolved gas is proportional to its partial pressure in the gas phase. The proportionality factor is called the Henry's law constant. Different gases would have different constants under different conditions. Below is the henry’s Law constant for CO2 in water at 298 K is presented in Table 1 for number of possible forms of the equation. Table 1: henry's law constants under different conditions From Henry’s statement, temperature is a factor.

Below is a description of temperature dependency on Henry’s constant law 2.3.1 Temperature dependency of Henry’s Law constant Depending on the temperature of the water used as a solvent in the absorption column, the value of the Henry’s law constant will change. This temperature dependency is expressed as follows. 𝐻𝑖, = 𝐻𝑖,𝑝,𝑇298𝑒𝑥𝑝 [𝐶 (𝑇 1 – 𝑇1 298)] Where: T = Water temperature in K T298 = 298 K (standard temperature) C = 2400 K (Constant for CO2) To convert Hi,cp into a format that you can use to plot the equilibrium curve, you need to convert Hi,cp into the form Hi, px.

This is done as follows: 𝐻𝑖,𝑝𝑥 = 𝜌𝑤𝑎𝑡𝑒𝑟 𝑅𝑀𝑀𝑤𝑎𝑡𝑒𝑟𝐻𝑖,𝑐𝑝 Where: ρwater = 1 kg.L-1 RMMwater = 0.018 kg.mol-1 Equilibrium curves may be plotted, in terms of Mole Ratios X and Y, for each water temperature used, where: 𝑌𝑖 = 𝐻𝑖, 𝑃 𝑋𝑖 1 + (1 − 𝐻𝑖 ,𝑥) 𝑋𝑖 P = Pressure in Absorber in units of atmospheres. (Typically the absorber is operating under atmospheric conditions.) A graphical presentation of the temperature dependency of Henry’s law constant is as shown in the figure 1 below.

With this theoretical framework in mind, the experiment was carried as described in section 3 below. Figure 1 CO2/Water equilibria at 1 bar pressure for various temperatures in terms of mole ratios.

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