In our experiment, the hypothesis stated that distillation would be more efficient due to the amount of energy required to separate and recombine oxygen and hydrogen bonds because the theory indicates that water evaporation requires 1/5 the the energy of breaking the hydrogen and oxygen bonds (40.65 kJ/mol vs. 237.1 kJ/mol). The hypothesis was incorrect as much less energy was required for electrolysis which appeared to be due to the distallation apparatus being very energy inefficient as much heast was lost to the air. Furthermore, the results show that 0.01% more of deuterium was depleted for electrolysis. In our background research, we learned why deuterium is harmful is because it adversely affects the shape of enzyme molecules involved in DNA processes, and we also learned about the energy required to evaporate water and that bonds between atoms in molecules require great energy to split in most scenarios.
For both distillation and electrolysis and the control, 1mL of deuterium per each 50mL of water was added to view the change in deuterium levels on a large enough scale. In distillation, we built a distillation device with a condenser, a hot plate, a condenser stand, and a sink. We planned for the water to boil at 100° Celsius, leaving behind the deuterium-enriched water that has a higher boiling point. The deuterium depleted water vapors would then travel from the flask on the hotplate into the tube attached to its stopper, then be cooled down by a stream of cold water around it and change states into liquid when entering the condenser. Then the deuterium depleted water would travel down the condenser into the flask at the bottom collecting the deuterium depleted water. This was done twice in order to achieve more accurate results. For electrolysis, we used a PEM fuel cell kit with a motor and battery and ran a current through two electrodes in order to force each gas to rise (explained in further detail later) into the collection tubes. The we reversed the fuel cell and allowed each gas to combine within the fuel cell depleted of deuterium. In the process, electricity would also be produced, and to ensure that the whole process worked and to release the energy a motor was connected and would spin if electricity was produced. Meanwhile, we recorded the time and measured the current of the process in order to eventually find the number of joules required per mL of water. Two trials were done for electrolysis, but due to the small volumes of water output, the samples and times were combined. Then, we sent the samples to UBC to detect the amounts of deuterium within the samples as measuring deuterium levels requires very speciallized equipment and we were not permitted to operate mass spectrometers ourselves.
In this experiment, the independent variable was the method of producing deuterium-depleted water, while the dependent variables were the energy input and concentration of deuterium. As controls, distilled water was combined with a small amount of deuterium in order to compare the methods’ results versus non-deuterium-depleted water. Throughout the experiment, the amount of deuterium added, the amount of water, and amount energy inputted were controlled. It should be noted that we chose to add Deuterium Oxide to the starting samples so that we could measure greater variability in the resultant deuterium-depleted output samples.
As seen in Table 1 and Figure 1, electrolysis requires very little energy compared to distillation, the first trial of distillation requiring approximately 16137 joules per mL of water and the second trial requiring 16800 joules per mL of water, while electrolysis required approximately 20 joules per mL of water in order to operate. This was likely because in electrolysis, a reverse voltage of only 1.23 volts is run through the water very briefly from the battery, giving electrical charge to the anode (positively charged electrode) and cathode (negatively charged electrode). The anode is in one container, filled with water, while the cathode is in another, also filled with water. Since water is made up of two positive hydrogen atoms and one negative oxygen atom, the oxygen will repel the cathode, causing it to rise in bubbles in that container and go through a tube into one side of the fuel cell. Hydrogen will repel the anode, and thus rise and go through a tube onto the other side in the container. When the hydrogen hits the catalyst, it splits into protons and electrons. A proton exchange membrane allows the protons to pass, while electrons are blocked and forced to run through an electrical circuit to produce energy as water is depleted of deuterium – an added bonus. The neutrons that occur to form deuterium would also have been halted by the proton exchange membrane, and would have remained static for they cannot run through a circuit. Meanwhile, the protons of the hydrogen would react with the oxygen in the catalyst (a device that speeds up chemical reactions) to form water. The water would then flow out of the fuel cell, depleted of deuterium.
For distillation on the other hand, it required a constant current high enough to cause the water to heat up to 100° C. Distillation was also a very slow process, and thus required a high current for the hot plate for a long period of time just to produce a millilitre of water. This meant that electrolysis required much less energy for it only required a small current for shorter period of time. In Tables 1 and Figure 2, it can be seen that distillation gave off a much higher water output, depleting 58mL of water of deuterium in the first trial and 30mL in the second trial, while electrolysis produced only 4.4mL of deuterium depleted water. However, this was simply because the fuel cell was small, and this problem could be easily solved by using a larger fuel cell which will also be more expensive. Also, since the energy required has been recorded as per mL, it does not affect the calculations for the efficiency.
As displayed in Table 1 and Figures 3-5, distillation and electrolysis were both were highly successful in depleting water of deuterium, but electrolysis was more successful. In the mass spectrometer, 0.16% of deuterium within the water was detected for distillation in both trials as opposed to the 5.22% of deuterium within the control sample, while 0.15% of deuterium was detected in electrolysis. Although seeming to be a small difference, 0.01% is actually quite a lot relatively as the mass spectrometer is very precise. Furthermore, in tap water, there is often much less deuterium as there was in the control – more deuterium was added into all of the samples at the beginning so that the levels of deuterium were at a large enough scale that they could be detected. Therefore, 0.01% of deuterium could be the difference between some deuterium and no deuterium at all if the experiment was performed just using tap water. The higher success rate of the electrolysis was a result of traces of deuterium boiling off with the water in the distillation process as the temperature could not be controlled completely – the boiling point of deuterium oxide is only 1.4° C higher than the boiling point of water. While unexpected, our results were based on what would theoretically happen.
Although the experiment was highly successful, there were several improvements that could be made. Within the distillation process, the temperature could have been controlled more precisely as there is only a slight difference in boiling points between deuterium and the rest of the water and this required experience in controlling the temperature of the hot plate. Some energy was lost on the hot plate as the hot plate heated the air and equipment. Also, the water was allowed to nearly boil dry on the hot plate in Trial 1 of distillation, possibly allowing some deuterium to re-enter the water outputted on the other side of the condenser. In future, larger volumes of water should be run through the condenser to improve the efficiency of the distillation method. For electrolysis, the energy output produced while the motor was connected was not measured, which would have recovered some of the energy that was used for the electrolysis. As another consideration for the future, a larger fuel cell should have been used to make the method more efficient.
For both distillation and electrolysis and the control, 1mL of deuterium per each 50mL of water was added to view the change in deuterium levels on a large enough scale. In distillation, we built a distillation device with a condenser, a hot plate, a condenser stand, and a sink. We planned for the water to boil at 100° Celsius, leaving behind the deuterium-enriched water that has a higher boiling point. The deuterium depleted water vapors would then travel from the flask on the hotplate into the tube attached to its stopper, then be cooled down by a stream of cold water around it and change states into liquid when entering the condenser. Then the deuterium depleted water would travel down the condenser into the flask at the bottom collecting the deuterium depleted water. This was done twice in order to achieve more accurate results. For electrolysis, we used a PEM fuel cell kit with a motor and battery and ran a current through two electrodes in order to force each gas to rise (explained in further detail later) into the collection tubes. The we reversed the fuel cell and allowed each gas to combine within the fuel cell depleted of deuterium. In the process, electricity would also be produced, and to ensure that the whole process worked and to release the energy a motor was connected and would spin if electricity was produced. Meanwhile, we recorded the time and measured the current of the process in order to eventually find the number of joules required per mL of water. Two trials were done for electrolysis, but due to the small volumes of water output, the samples and times were combined. Then, we sent the samples to UBC to detect the amounts of deuterium within the samples as measuring deuterium levels requires very speciallized equipment and we were not permitted to operate mass spectrometers ourselves.
In this experiment, the independent variable was the method of producing deuterium-depleted water, while the dependent variables were the energy input and concentration of deuterium. As controls, distilled water was combined with a small amount of deuterium in order to compare the methods’ results versus non-deuterium-depleted water. Throughout the experiment, the amount of deuterium added, the amount of water, and amount energy inputted were controlled. It should be noted that we chose to add Deuterium Oxide to the starting samples so that we could measure greater variability in the resultant deuterium-depleted output samples.
As seen in Table 1 and Figure 1, electrolysis requires very little energy compared to distillation, the first trial of distillation requiring approximately 16137 joules per mL of water and the second trial requiring 16800 joules per mL of water, while electrolysis required approximately 20 joules per mL of water in order to operate. This was likely because in electrolysis, a reverse voltage of only 1.23 volts is run through the water very briefly from the battery, giving electrical charge to the anode (positively charged electrode) and cathode (negatively charged electrode). The anode is in one container, filled with water, while the cathode is in another, also filled with water. Since water is made up of two positive hydrogen atoms and one negative oxygen atom, the oxygen will repel the cathode, causing it to rise in bubbles in that container and go through a tube into one side of the fuel cell. Hydrogen will repel the anode, and thus rise and go through a tube onto the other side in the container. When the hydrogen hits the catalyst, it splits into protons and electrons. A proton exchange membrane allows the protons to pass, while electrons are blocked and forced to run through an electrical circuit to produce energy as water is depleted of deuterium – an added bonus. The neutrons that occur to form deuterium would also have been halted by the proton exchange membrane, and would have remained static for they cannot run through a circuit. Meanwhile, the protons of the hydrogen would react with the oxygen in the catalyst (a device that speeds up chemical reactions) to form water. The water would then flow out of the fuel cell, depleted of deuterium.
For distillation on the other hand, it required a constant current high enough to cause the water to heat up to 100° C. Distillation was also a very slow process, and thus required a high current for the hot plate for a long period of time just to produce a millilitre of water. This meant that electrolysis required much less energy for it only required a small current for shorter period of time. In Tables 1 and Figure 2, it can be seen that distillation gave off a much higher water output, depleting 58mL of water of deuterium in the first trial and 30mL in the second trial, while electrolysis produced only 4.4mL of deuterium depleted water. However, this was simply because the fuel cell was small, and this problem could be easily solved by using a larger fuel cell which will also be more expensive. Also, since the energy required has been recorded as per mL, it does not affect the calculations for the efficiency.
As displayed in Table 1 and Figures 3-5, distillation and electrolysis were both were highly successful in depleting water of deuterium, but electrolysis was more successful. In the mass spectrometer, 0.16% of deuterium within the water was detected for distillation in both trials as opposed to the 5.22% of deuterium within the control sample, while 0.15% of deuterium was detected in electrolysis. Although seeming to be a small difference, 0.01% is actually quite a lot relatively as the mass spectrometer is very precise. Furthermore, in tap water, there is often much less deuterium as there was in the control – more deuterium was added into all of the samples at the beginning so that the levels of deuterium were at a large enough scale that they could be detected. Therefore, 0.01% of deuterium could be the difference between some deuterium and no deuterium at all if the experiment was performed just using tap water. The higher success rate of the electrolysis was a result of traces of deuterium boiling off with the water in the distillation process as the temperature could not be controlled completely – the boiling point of deuterium oxide is only 1.4° C higher than the boiling point of water. While unexpected, our results were based on what would theoretically happen.
Although the experiment was highly successful, there were several improvements that could be made. Within the distillation process, the temperature could have been controlled more precisely as there is only a slight difference in boiling points between deuterium and the rest of the water and this required experience in controlling the temperature of the hot plate. Some energy was lost on the hot plate as the hot plate heated the air and equipment. Also, the water was allowed to nearly boil dry on the hot plate in Trial 1 of distillation, possibly allowing some deuterium to re-enter the water outputted on the other side of the condenser. In future, larger volumes of water should be run through the condenser to improve the efficiency of the distillation method. For electrolysis, the energy output produced while the motor was connected was not measured, which would have recovered some of the energy that was used for the electrolysis. As another consideration for the future, a larger fuel cell should have been used to make the method more efficient.