bthoole's blog

As detailed above, solid industrial wastes, mostly from combustion residues, act as possible sources for mineral sequestration of carbon dioxide. Cement production and used concrete are capable of this sequestration and similar processes that occur during the carbonation reaction also occurs with the waste material from steel slag. This offers another potential source to combat emissions produced during the production of these industrial products and store the greenhouse gas as a stable product. The benefit of using this material is its proximity to the point sources of carbon dioxide, which is to say the waste steel slag is produced alongside the steel product. Accompanying the closeness to the source of carbon dioxide release is the lower cost in using the steel slag than mining ore for natural sequestration.

Both the steel slag and cement offer a potential sink to store carbon in and both processes involve a form of ion extraction, usually calcium, to combine with the carbon dioxide to form the carbonate material. As was explained in the steel slag pilot plant facility, a solvent was necessary to promote this migration of calcium ions in the solid steel slag to a more reactive state that could combine with the carbon dioxide. However, other solvents are available to perform similar functions, just not in the context of steel slags. Other such solvents are sodium based and have been tested to see their practicality when used with a feedstock of the magnesium rich serpentinite.

In this new sequestration process proposed by Iizuka, waste cement used in reference to concrete that is being torn up from how it had been used. Since there is a continual source of waste concrete from dismantled buildings, a long-term source of waste cement is expected. This waste is considered to be source of the necessary ions that are needed for the sequestration of carbon dioxide. By sequestering carbon with calcium and magnesium in the form of carbonates, a stable solution that is environmentally benign is produced. Other methods may sequester carbon dioxide as liquid, which could result in the reduction of pH in seawater or could evaporate to the surface and back to the atmosphere. The process of using waste concrete as a means to sequester carbon dioxide is demonstrated in Figure 1, which shows the order of events that can lead to the recycling of waste cement or as just a means of sequestration.

There are three main types of microtubules, which perform different functions in the cell and occur during different phases in cell division. Aster microtubules extend from the spindle pole towards the cell cortex. Motor proteins attach themselves and exert an outward pulling force on the spindle poles to help position the poles correctly and pull the poles apart in anaphase B. The second type of microtubule is the kinetochore microtubule which connect the chromosome to the spindle pole and exerts a pulling force on the chromosome in anaphase A. The third type of microtubule is the interpolar microtubule, which overlaps microtubules in the center of the spindle. The proteins that bind here are important in stabilizing the spindle. These microtubules and their respective tasks are important to the phases of anaphase. Anaphase A involves the chromosomes being pulled poleward by the shortening of the kinetochore microtubules. Anaphase B involves the poles themselves as they are pushed and pulled apart. A sliding force is generated between interpolar microtubules to push the poles apart, while a pulling force acts directly on the poles to pull them apart.

The criterion for the transition between ripples and upper plane bed do hold for the observations from the data. Ripples and dunes occur when the shear stress is greater than the 3*Tcr and transitions to an upper plane bed when the Froude number occurs between 0.84 and 1. The graph shows that the upper plane bed points occur past the 3*Tcr limit and are mainly grouped between the boundaries of 0.84 and 1 Froude numbers. There are some examples of an upper plane bed occurring outside of these limits, with two occurring below 0.84 and one above 1. However, these Froude number boundaries represent generalities and do not set a strict limit that always results in the proper bedform given the conditions. Given what is seen, the other bedforms typically stay where they are expected, and the upper plane bed data points are mostly within the boundary.

For larger grain sizes, more energy is going to be required to move them. This means that with increases in grain size, the Tcr and calculated Utcr will be larger values. With larger Tcr and Utcr values, ripples and dunes will not start forming for larger grain sizes until there is a larger flow velocity. The boundaries of the Froude number will remain at 0.8 and 1 in order to differentiate between bedforms, but their positioning on the graph will also change as the flow velocity U increases. An increase in that value will increase the values generated to plot the lines for when the Froude number is 1 or 0.8. Overall, a similar dispersal of the bedform types should be seen as far the relative positioning of each group juxtaposed to the corresponding Froude numbers and other bedform types. What will be different than this graph is the scale of the axes.

Of the problems facing the world today, none may be more pressing than the rise in worldwide temperature and the ensuing difficulties that come with global climate change. All the problems that face humanity today will only be compounded by the effects of climate change. There will be increased wildfires, massive dying of coral reefs, increases in human migration and many more deaths that can be directly attributed to the increased temperatures and indirectly, through increases in famine and drought. The world’s drinkable water supply is already decreasing, with some reservoirs decreasing to the point where tap water has to be shut off completely, like in Cape Town, South Africa and the people have to wait in lines guarded by armed guards just to have access to drinkable water. It is predicted that water will be the source of conflict in the future, the way oil has been in the past.

Years of industrialization and little to no regulation on what can be emitted into the atmosphere has led to a changing climate which will only grow worse with time. The current shared opinion among scientists is that humans need to limit the rise in temperature to only two degrees Celsius above preindustrial levels in order to avoid a point where the increase in temperature reaches a point where it would no longer be able to be controlled or averted. Currently, climate change is occurring because of the presence of “greenhouse” gases in the atmosphere, mostly methane and carbon dioxide. These gases act as a blanket of sorts for the earth and trap incoming radiation from the sun, thus heating the planet. This process drives other factors that then contribute to the increased temperatures as well. With the increase in temperature, glaciers and other land bound ice are melting and raising sea levels. This affects global temperature in two ways. The first is that the ice normally serves as a source of albedo that stops the sunlight from being absorbed by the darker colored earth and reflects it back into the atmosphere. The second is that as sea levels rise, it provides more water to absorb heat, again raising temperatures. These are just two examples of how climate change has the potential to reach a tipping point that, if reached, will not be able to be stopped.

A one to one mixture of alcohol and carboxylic acid will usually yield an equilibrium mixture that is about 70% ester. The experiment carried out did not use a one to one ratio and instead used 13 mmol of carboxylic acid to 11 mmol of alcohol. This was in an attempt to react all the alcohol and not limit it, but the reaction of 1-propanol and propionic acid produced a percent yield of 19.81%. The final product of ester after the drying work up was 0.253 g when the theoretical put the grams of 1-propyl propionate ester at 1.255 g. The final percent yield may be the result of an incomplete separation during the reflux between the water and organic layers. The reflux filled the side arm quickly and required the top layer to be dumped back into the round-bottom flask multiple times during the 15 min heating period. A higher ester yield may have been possible if the separation occurred at a slower rate so that the side arm did not fill so quickly, or if the side arm were larger. If the side arm were larger, it would allow for more catchment and a more defined layer to distinguish the organic from the water. The better distinction would also allow for only the organic layer to be removed after the 15 min reflux. Given that the reflux did not completely separate the organic product from the water, some of the ester may have been removed as the aqueous layer during the work up which would have lowered the final volume and therefore the percent yield. Still, the IR analysis confirmed the existence of an ester based on the peaks seen, so the esterification reaction between 1-propanol and propionic acid was successful in producing 1-propyl propionate.

The final product was also qualitatively assessed for odor and compared to the odor of the other esters and the starting products used in the reaction. The esters shared a sweet-smelling, fruity odor. The 1-propyl-propionate ester formed in the final product had a smell of pineapple or pear, which was distinguishable from the other esters which had a more banana like fragrance. The product also had a slight odor of alcohol, similar to that of nail polish remover, which ma be detectable traces of alcohol which was seen present in the IR spectrum. The starting components, 1-propanol and propionic acid did not share the fruity fragrance of the final ester and were instead unpleasurable scents. Both had a rancid odor, with the 1-propanol being similar to that of ethanol, another alcohol.

After the solution was refluxed to worked up to remove the water, the final product was analyzed using infrared spectroscopy. The spectroscopy analysis provided peaks that correspond to that of an ester, which is what was expected and can confirm the esterification process in the synthesis of 1-propyl propionate. The IR spectrum showed a peak just to the right of 3000 cm^-1 at 2972.43 cm^-1. This peak corresponds to the alkyl carbon-hydrogen bond in the ester. The stretch that starts at peak 1740.83 cm^-1 is a measurement of the double bond between carbon and oxygen. These are the results that would be seen in a sample of pure ester, but the IR spectrum also gives peak values above 3000 cm^-1, which suggests impurities containing a hydroxyl oxygen and hydrogen bond. The peak is highest at 3453.69 cm^-1. This impurity could be a result of left-over water or a result of alcohol contamination from the 1-propanol.